From 9f394930a68d169312177a16dc3a235518bb3c25 Mon Sep 17 00:00:00 2001
From: Wolfgang Bangerth <bangerth@colostate.edu>
Date: Sat, 5 Feb 2022 16:34:30 -0700
Subject: [PATCH] More changes of single-character things.

---
 examples/step-11/step-11.cc                   |   2 +-
 examples/step-12/step-12.cc                   |   2 +-
 examples/step-12b/step-12b.cc                 |   4 +-
 examples/step-13/step-13.cc                   |   2 +-
 examples/step-17/step-17.cc                   |   2 +-
 examples/step-18/step-18.cc                   |   4 +-
 examples/step-24/step-24.cc                   |   4 +-
 examples/step-28/step-28.cc                   |   6 +-
 examples/step-35/step-35.cc                   |   2 +-
 examples/step-36/step-36.cc                   |   6 +-
 examples/step-37/step-37.cc                   |  10 +-
 examples/step-42/step-42.cc                   |   6 +-
 examples/step-44/step-44.cc                   |  10 +-
 examples/step-48/step-48.cc                   |   4 +-
 examples/step-49/step-49.cc                   |   2 +-
 examples/step-57/step-57.cc                   |   2 +-
 examples/step-66/step-66.cc                   |   2 +-
 examples/step-67/step-67.cc                   |   4 +-
 examples/step-68/step-68.cc                   |   4 +-
 examples/step-69/step-69.cc                   |   4 +-
 examples/step-75/step-75.cc                   |   2 +-
 examples/step-76/step-76.cc                   |   4 +-
 examples/step-79/step-79.cc                   | 168 +++---
 include/deal.II/base/exceptions.h             |   6 +-
 include/deal.II/base/function_cspline.h       |   2 +-
 include/deal.II/base/function_parser.h        |   2 +-
 include/deal.II/base/index_set.h              |   6 +-
 include/deal.II/base/polynomial_space.h       |   2 +-
 include/deal.II/base/table.h                  |   2 +-
 include/deal.II/base/table_handler.h          |   2 +-
 include/deal.II/base/tensor_function_parser.h |   4 +-
 include/deal.II/dofs/dof_tools.h              |   8 +-
 include/deal.II/fe/fe.h                       |   2 +-
 include/deal.II/fe/fe_dg_vector.templates.h   |   4 +-
 include/deal.II/fe/fe_tools.h                 |   4 +-
 include/deal.II/grid/reference_cell.h         |   6 +-
 .../lac/affine_constraints.templates.h        |   4 +-
 include/deal.II/lac/block_matrix_base.h       |   2 +-
 .../lac/block_sparse_matrix.templates.h       |   2 +-
 include/deal.II/lac/cuda_sparse_matrix.h      |   2 +-
 include/deal.II/lac/la_parallel_vector.h      |   2 +-
 .../lac/la_parallel_vector.templates.h        |   2 +-
 include/deal.II/lac/petsc_vector_base.h       |   2 +-
 .../deal.II/lac/read_write_vector.templates.h |   2 +-
 include/deal.II/lac/sparse_matrix.h           |   2 +-
 include/deal.II/lac/sparse_mic.h              |   2 +-
 include/deal.II/lac/trilinos_sparse_matrix.h  |  11 +-
 .../deal.II/lac/trilinos_sparsity_pattern.h   |  11 +-
 include/deal.II/lac/trilinos_vector.h         |   2 +-
 .../deal.II/matrix_free/dof_info.templates.h  |   8 +-
 include/deal.II/meshworker/local_results.h    |   4 +-
 .../deal.II/multigrid/mg_transfer.templates.h |   6 +-
 .../deal.II/optimization/line_minimization.h  |  14 +-
 include/deal.II/physics/notation.h            |   4 +-
 tests/adolc/step-44.cc                        |  10 +-
 tests/aniso/fe_tools.cc                       |   2 +-
 tests/aniso/refine_and_coarsen_anisotropic.cc |   2 +-
 tests/base/aligned_vector_01.cc               |  10 +-
 tests/base/aligned_vector_02.cc               |   6 +-
 tests/base/aligned_vector_03.cc               |  10 +-
 tests/base/aligned_vector_05.cc               |   6 +-
 tests/base/aligned_vector_move.cc             |   4 +-
 tests/base/anisotropic_2.cc                   |  12 +-
 tests/base/bounding_box_1.cc                  |  10 +-
 tests/base/bounding_box_6.cc                  |   6 +-
 tests/base/consensus_algorithm_01.cc          |   2 +-
 tests/base/derivative_forms_04.cc             |   2 +-
 .../base/function_from_function_objects_01.cc |   2 +-
 tests/base/function_parser_02.cc              |  36 +-
 tests/base/function_parser_05.cc              |   2 +-
 tests/base/function_parser_08.cc              |   2 +-
 tests/base/functions_04.cc                    |   6 +-
 tests/base/functions_09.cc                    |   4 +-
 tests/base/functions_12.cc                    |   4 +-
 tests/base/functions_cspline.cc               |   4 +-
 tests/base/functions_incremental_01.cc        |   4 +-
 tests/base/functions_incremental_02.cc        |   4 +-
 tests/base/functions_singularity.cc           |   6 +-
 tests/base/gauss_lobatto.cc                   |   2 +-
 tests/base/geometric_utilities_01.cc          |   4 +-
 tests/base/geometry_info_2.cc                 |   2 +-
 tests/base/geometry_info_3.cc                 |   2 +-
 tests/base/geometry_info_4.cc                 |   2 +-
 tests/base/geometry_info_5.cc                 |   2 +-
 tests/base/geometry_info_6.cc                 |   2 +-
 tests/base/geometry_info_7.cc                 |   2 +-
 tests/base/geometry_info_8.cc                 |   8 +-
 tests/base/graph_coloring_01.cc               |   2 +-
 tests/base/graph_coloring_02.cc               |   2 +-
 tests/base/graph_coloring_03.cc               |   2 +-
 tests/base/hdf5_03.cc                         | 382 ++++++-------
 tests/base/hdf5_04.cc                         | 426 +++++++-------
 tests/base/hdf5_05.cc                         | 540 ++++++++----------
 tests/base/hdf5_06.cc                         | 437 +++++++-------
 tests/base/hierarchical.cc                    |   4 +-
 tests/base/index_set_iterate_01.cc            |   6 +-
 tests/base/index_set_readwrite_03.cc          |   2 +-
 tests/base/mpi_create_partitioning_01.cc      |   2 +-
 .../mpi_evenly_distributed_partitioning_01.cc |   2 +-
 .../base/mpi_noncontiguous_partitioner_01.cc  |   4 +-
 .../base/mpi_noncontiguous_partitioner_02.cc  |   4 +-
 .../base/mpi_noncontiguous_partitioner_03.cc  |   4 +-
 tests/base/mpi_some_to_some_02.cc             |   2 +-
 tests/base/polynomial1d.cc                    |  10 +-
 tests/base/polynomial_jacobi.cc               |   4 +-
 tests/base/polynomial_jacobi_roots.cc         |   2 +-
 tests/base/polynomial_jacobi_roots_ld.cc      |   2 +-
 tests/base/polynomials_adini_01.cc            |   2 +-
 tests/base/polynomials_br.cc                  |   4 +-
 tests/base/quadrature_check_tensor_product.cc |   2 +-
 tests/base/quadrature_move_01.cc              |   4 +-
 tests/base/quadrature_move_02.cc              |   4 +-
 tests/base/quadrature_qiterated_01.cc         |   4 +-
 tests/base/quadrature_sorted_test.cc          |   4 +-
 tests/base/quadrature_test.cc                 |   4 +-
 tests/base/table.cc                           |  18 +-
 tests/base/taylor_estimate_function_bounds.cc |   4 +-
 tests/base/utilities_02b.cc                   |   4 +-
 tests/base/utilities_13.cc                    |   4 +-
 tests/base/utilities_14.cc                    |   2 +-
 tests/base/utilities_17.cc                    |   4 +-
 tests/base/utilities_18.cc                    |   2 +-
 tests/base/utilities_19.cc                    |   2 +-
 tests/base/utilities_pack_unpack_03.cc        |   2 +-
 tests/base/vectorization_05.cc                |   6 +-
 tests/base/vectorization_06.cc                |   2 +-
 tests/base/vectorization_08.cc                |   2 +-
 tests/base/vectorization_10.cc                |   6 +-
 tests/base/vectorization_12.cc                |   2 +-
 tests/base/vectorization_13.cc                |   4 +-
 tests/base/vectorization_15.cc                |   6 +-
 tests/bits/anna_4.cc                          |   2 +-
 tests/bits/apply_boundary_values_01.cc        |   2 +-
 tests/bits/apply_boundary_values_02.cc        |   2 +-
 tests/bits/block_sparse_matrix_iterator_01.cc |   2 +-
 tests/bits/chunk_sparse_matrix_11.cc          |   2 +-
 tests/bits/chunk_sparse_matrix_12.cc          |   2 +-
 tests/bits/chunk_sparse_matrix_13.cc          |   2 +-
 tests/bits/distorted_cells_01.cc              |   4 +-
 tests/bits/distorted_cells_07.cc              |   2 +-
 tests/bits/fe_field_function_03.cc            |   4 +-
 tests/bits/fe_tools_01a.cc                    |   2 +-
 tests/bits/fe_tools_01b.cc                    |   2 +-
 tests/bits/fe_tools_01c.cc                    |   2 +-
 tests/bits/find_cell_1.cc                     |   2 +-
 tests/bits/find_cell_2.cc                     |   2 +-
 tests/bits/find_cell_3.cc                     |   2 +-
 tests/bits/find_cell_4.cc                     |   2 +-
 tests/bits/find_cell_5.cc                     |   2 +-
 tests/bits/find_cell_8.cc                     |   2 +-
 tests/bits/find_cell_9.cc                     |   2 +-
 tests/bits/find_cell_alt_1.cc                 |   2 +-
 tests/bits/find_cell_alt_2.cc                 |   2 +-
 tests/bits/find_cell_alt_3.cc                 |   2 +-
 tests/bits/find_cell_alt_4.cc                 |   2 +-
 tests/bits/find_cell_alt_5.cc                 |   2 +-
 tests/bits/find_cell_alt_6.cc                 |   4 +-
 tests/bits/find_cells_adjacent_to_vertex_1.cc |   2 +-
 tests/bits/find_closest_vertex_1.cc           |   2 +-
 tests/bits/make_boundary_constraints_01.cc    |   2 +-
 tests/bits/make_boundary_constraints_02.cc    |   2 +-
 .../bits/map_dofs_to_support_points_hp_01.cc  |   2 +-
 tests/bits/periodicity_01.cc                  |   2 +-
 tests/bits/periodicity_02.cc                  |   2 +-
 tests/bits/periodicity_03.cc                  |   2 +-
 tests/bits/periodicity_04.cc                  |   2 +-
 tests/bits/periodicity_09.cc                  |   2 +-
 ...efine_and_coarsen_for_active_cell_index.cc |   2 +-
 ...ne_and_coarsen_for_active_cell_index_02.cc |   2 +-
 ...ne_and_coarsen_for_active_cell_index_03.cc |   2 +-
 ...ne_and_coarsen_for_active_cell_index_04.cc |   2 +-
 ...ne_and_coarsen_for_active_cell_index_05.cc |   2 +-
 tests/bits/refine_and_coarsen_for_parents.cc  |   2 +-
 .../bits/refine_and_coarsen_for_parents_02.cc |   2 +-
 .../bits/refine_and_coarsen_for_parents_03.cc |   2 +-
 tests/bits/step-11.cc                         |   2 +-
 tests/bits/step-13.cc                         |   4 +-
 tests/bits/step-14.cc                         |   2 +-
 tests/bits/unit_support_points.cc             |   4 +-
 tests/boost/extract_representative_set_02.cc  |   4 +-
 tests/codim_one/grid_in_out_03.cc             |   2 +-
 tests/codim_one/hanging_nodes_02.cc           |   2 +-
 tests/codim_one/hanging_nodes_03.cc           |   2 +-
 tests/codim_one/integrate_log.cc              |   2 +-
 .../measure_of_distorted_codim_one_face.cc    |   2 +-
 tests/codim_one/tensor_matrix_conversion.cc   |   8 +-
 .../data_out_base_vtu_compression_levels.cc   |   2 +-
 tests/distributed_grids/2d_dofhandler_01.cc   |   2 +-
 .../distributed_grids/get_boundary_ids_01.cc  |   2 +-
 .../grid_tools_exchange_cell_data_01.cc       |   4 +-
 .../grid_tools_exchange_cell_data_02.cc       |   4 +-
 .../grid_tools_exchange_cell_data_03.cc       |   4 +-
 .../grid_tools_exchange_cell_data_04.cc       |   4 +-
 .../distributed_grids/hp_2d_dofhandler_01.cc  |   2 +-
 .../distributed_grids/solution_transfer_04.cc |   4 +-
 tests/distributed_grids/subdomain_id_01.cc    |   2 +-
 tests/dofs/block_list_02.cc                   |  20 +-
 tests/dofs/block_list_05.cc                   |   8 +-
 tests/dofs/dof_constraints_01.cc              |   2 +-
 tests/dofs/dof_constraints_02.cc              |   2 +-
 tests/dofs/dof_constraints_03.cc              |   2 +-
 tests/dofs/dof_constraints_04.cc              |   2 +-
 tests/dofs/dof_constraints_05.cc              |   2 +-
 tests/dofs/dof_constraints_06.cc              |   2 +-
 tests/dofs/dof_constraints_07.cc              |   2 +-
 tests/dofs/dof_constraints_08.cc              |   2 +-
 tests/dofs/dof_constraints_09.cc              |   2 +-
 tests/dofs/dof_constraints_10.cc              |   2 +-
 tests/dofs/dof_constraints_11.cc              |   2 +-
 tests/dofs/dof_constraints_11_x.cc            |   2 +-
 tests/dofs/dof_handler_number_cache_02.cc     |   4 +-
 tests/dofs/dof_renumbering_10.cc              |  10 +-
 tests/dofs/dof_tools_01a.cc                   |   2 +-
 tests/dofs/dof_tools_01a_constraints_false.cc |   2 +-
 tests/dofs/dof_tools_01a_constraints_true.cc  |   2 +-
 tests/dofs/dof_tools_01a_subdomain.cc         |   2 +-
 tests/dofs/dof_tools_01b.cc                   |   2 +-
 tests/dofs/dof_tools_01c.cc                   |   2 +-
 tests/dofs/dof_tools_01d.cc                   |   2 +-
 tests/dofs/dof_tools_02a.cc                   |   2 +-
 tests/dofs/dof_tools_02a_constraints_false.cc |   2 +-
 tests/dofs/dof_tools_02a_constraints_true.cc  |   2 +-
 tests/dofs/dof_tools_02a_subdomain.cc         |   2 +-
 tests/dofs/dof_tools_02b.cc                   |   2 +-
 tests/dofs/dof_tools_02c.cc                   |   2 +-
 tests/dofs/dof_tools_02d.cc                   |   2 +-
 tests/dofs/dof_tools_07.cc                    |   2 +-
 tests/dofs/dof_tools_08.cc                    |   2 +-
 tests/dofs/dof_tools_09.cc                    |   4 +-
 tests/dofs/dof_tools_10.cc                    |   2 +-
 tests/dofs/dof_tools_13.cc                    |   4 +-
 tests/dofs/dof_tools_13a.cc                   |   4 +-
 tests/dofs/dof_tools_15a.cc                   |   2 +-
 tests/dofs/dof_tools_15b.cc                   |   2 +-
 tests/dofs/dof_tools_15c.cc                   |   2 +-
 tests/dofs/dof_tools_15d.cc                   |   2 +-
 tests/dofs/dof_tools_16a.cc                   |   2 +-
 tests/dofs/dof_tools_16b.cc                   |   2 +-
 tests/dofs/dof_tools_16c.cc                   |   2 +-
 tests/dofs/dof_tools_16d.cc                   |   2 +-
 tests/dofs/dof_tools_17a.cc                   |   2 +-
 tests/dofs/dof_tools_17b.cc                   |   2 +-
 tests/dofs/dof_tools_17c.cc                   |   2 +-
 tests/dofs/dof_tools_17d.cc                   |   2 +-
 tests/dofs/dof_tools_18a.cc                   |   2 +-
 tests/dofs/dof_tools_18a_1d.cc                |   2 +-
 tests/dofs/dof_tools_18b.cc                   |   2 +-
 tests/dofs/dof_tools_18c.cc                   |   2 +-
 tests/dofs/dof_tools_18d.cc                   |   2 +-
 tests/dofs/dof_tools_21_b.cc                  |   8 +-
 tests/dofs/dof_tools_21_c.cc                  |   8 +-
 ...t_dofs_with_support_contained_within_01.cc |   4 +-
 ...t_dofs_with_support_contained_within_03.cc |   4 +-
 ...t_dofs_with_support_contained_within_04.cc |   4 +-
 ...write_gnuplot_dof_support_point_info_01.cc |   4 +-
 ...write_gnuplot_dof_support_point_info_02.cc |   4 +-
 ...write_gnuplot_dof_support_point_info_03.cc |   4 +-
 tests/dofs/interpolate_boundary_values_01.cc  |   2 +-
 tests/dofs/map_dofs_to_support_points_01.cc   |   2 +-
 tests/fail/hp-step-14.cc                      |   2 +-
 tests/fail/hp-step-15.cc                      |   2 +-
 tests/fail/rt_4.cc                            |   2 +-
 tests/fail/rt_6.cc                            |   2 +-
 tests/fail/scalapack_15_b.cc                  |   4 +-
 tests/fail/step-15.cc                         |   2 +-
 tests/fe/bdm_1.cc                             |   2 +-
 tests/fe/bdm_16.cc                            |   2 +-
 tests/fe/bdm_3.cc                             |   2 +-
 tests/fe/bdm_5.cc                             |   2 +-
 tests/fe/cell_similarity_11.cc                |   4 +-
 tests/fe/cell_similarity_12.cc                |   4 +-
 tests/fe/cell_similarity_13.cc                |   4 +-
 tests/fe/copy_01.cc                           |   2 +-
 tests/fe/dgp_monomial_1.cc                    |   2 +-
 tests/fe/dgp_monomial_2.cc                    |   4 +-
 tests/fe/dgq_1.cc                             |   4 +-
 tests/fe/element_constant_modes.cc            |   2 +-
 .../fe/fe_abf_gradient_divergence_theorem.cc  |   4 +-
 tests/fe/fe_br.cc                             |   4 +-
 ...e_dgp_3rd_derivative_divergence_theorem.cc |   4 +-
 ...e_dgq_3rd_derivative_divergence_theorem.cc |   4 +-
 .../fe/fe_dgq_gradient_divergence_theorem.cc  |   4 +-
 tests/fe/fe_dgq_hessian_divergence_theorem.cc |   4 +-
 tests/fe/fe_enriched_07.cc                    |   2 +-
 tests/fe/fe_enriched_08.cc                    |   2 +-
 tests/fe/fe_enriched_08a.cc                   |   2 +-
 tests/fe/fe_enriched_color_01.cc              |   2 +-
 tests/fe/fe_enriched_color_03.cc              |   6 +-
 tests/fe/fe_enriched_color_04.cc              |   2 +-
 tests/fe/fe_enriched_color_05.cc              |   2 +-
 tests/fe/fe_enriched_color_07.cc              |  20 +-
 tests/fe/fe_enriched_color_08.cc              |   4 +-
 tests/fe/fe_face_values_1d.cc                 |   4 +-
 .../fe_nedelec_gradient_divergence_theorem.cc |   4 +-
 tests/fe/fe_nedelec_sz_face_orientation.cc    |   2 +-
 ..._nedelec_sz_gradient_divergence_theorem.cc |   4 +-
 .../fe_q_3rd_derivative_divergence_theorem.cc |   4 +-
 tests/fe/fe_q_bubbles.cc                      |   2 +-
 tests/fe/fe_q_dg0.cc                          |   6 +-
 tests/fe/fe_q_gradient_divergence_theorem.cc  |   4 +-
 tests/fe/fe_q_hessian_divergence_theorem.cc   |   4 +-
 ...hical_3rd_derivative_divergence_theorem.cc |   4 +-
 tests/fe/fe_rannacher_turek_01.cc             |   4 +-
 tests/fe/fe_rannacher_turek_02.cc             |   4 +-
 tests/fe/fe_rt_gradient_divergence_theorem.cc |   4 +-
 tests/fe/fe_rt_hessian_divergence_theorem.cc  |   2 +-
 tests/fe/fe_series_01.cc                      |   4 +-
 tests/fe/fe_series_02.cc                      |   4 +-
 tests/fe/fe_series_04.cc                      |   6 +-
 tests/fe/fe_series_05.cc                      |   4 +-
 tests/fe/fe_series_08.cc                      |   4 +-
 ...ystem_3rd_derivative_divergence_theorem.cc |   4 +-
 tests/fe/fe_system_components_base.cc         |   4 +-
 .../fe_system_generalized_support_points.cc   |   2 +-
 tests/fe/fe_tools.cc                          |   2 +-
 tests/fe/fe_values_view_16.cc                 |   2 +-
 tests/fe/fe_values_view_21.cc                 |   2 +-
 tests/fe/fe_values_view_21_nonsymmetric.cc    |   2 +-
 tests/fe/fe_values_view_22.cc                 |   2 +-
 tests/fe/fe_values_view_tensor_01.cc          |   8 +-
 tests/fe/fe_values_views_types.cc             |   2 +-
 tests/fe/injection_q_dg0.cc                   |   2 +-
 tests/fe/jacobians.cc                         |  16 +-
 tests/fe/jacobians_face.cc                    |  32 +-
 tests/fe/jacobians_face_cartesian.cc          |  32 +-
 tests/fe/jacobians_face_fe_field.cc           |  32 +-
 tests/fe/nedelec_3.cc                         |   2 +-
 tests/fe/restrict_prolongation_01.cc          |   2 +-
 tests/fe/rt_1.cc                              |   2 +-
 tests/fe/rt_13.cc                             |   2 +-
 tests/fe/rt_3.cc                              |   2 +-
 tests/fe/rt_5.cc                              |   2 +-
 tests/fe/rt_7.cc                              |   4 +-
 tests/fe/rt_bubbles_1.cc                      |   2 +-
 tests/fe/rt_bubbles_16.cc                     |   2 +-
 tests/fe/rt_bubbles_3.cc                      |   2 +-
 tests/fe/rtn_2.cc                             |   4 +-
 tests/feinterface/fe_interface_values_01.cc   |   4 +-
 tests/feinterface/fe_interface_values_05.cc   |   4 +-
 tests/feinterface/multigrid_01.cc             |   6 +-
 tests/feinterface/step-12.cc                  |   2 +-
 tests/full_matrix/full_matrix_move.cc         |  10 +-
 .../copy_serial_tria_06.cc                    |   2 +-
 .../repartitioning_07.cc                      |   2 +-
 tests/gla/block_mat_03.cc                     |   4 +-
 tests/gla/vec_01.cc                           |   4 +-
 tests/gla/vec_02.cc                           |   4 +-
 tests/gmsh/gmsh_api_02.cc                     |   4 +-
 tests/gmsh/gmsh_api_04.cc                     |   4 +-
 tests/grid/cell_id_01.cc                      |   4 +-
 tests/grid/cell_id_02.cc                      |   4 +-
 tests/grid/cell_id_03.cc                      |   4 +-
 tests/grid/cell_id_04.cc                      |   4 +-
 tests/grid/cell_id_06.cc                      |   2 +-
 tests/grid/cell_measure_01.cc                 |   6 +-
 tests/grid/flatten_grid_01.cc                 |   4 +-
 tests/grid/get_dof_to_support_patch_map_01.cc |   2 +-
 tests/grid/global_ids_01.cc                   |   2 +-
 tests/grid/global_ids_03.cc                   |   2 +-
 tests/grid/grid_generator_airfoil_01.cc       |   6 +-
 ...rid_generator_from_name_and_argument_01.cc |   2 +-
 ...erator_non_standard_orientation_mesh_2d.cc |   2 +-
 ...erator_non_standard_orientation_mesh_3d.cc |   2 +-
 tests/grid/grid_out_in_vtk_01.cc              |   2 +-
 tests/grid/grid_out_vtk_02.cc                 |   2 +-
 tests/grid/grid_parallelepiped_04.cc          |   4 +-
 ...ls_active_cell_layer_within_distance_01.cc |   2 +-
 ...ls_active_cell_layer_within_distance_02.cc |   2 +-
 tests/grid/grid_tools_bounding_box_01.cc      |   2 +-
 tests/grid/grid_tools_bounding_box_02.cc      |   2 +-
 tests/grid/grid_tools_halo_layer_01.cc        |   2 +-
 tests/grid/grid_tools_halo_layer_02.cc        |   2 +-
 tests/grid/grid_tools_halo_layer_03.cc        |   2 +-
 tests/grid/grid_tools_halo_layer_04.cc        |   2 +-
 tests/grid/grid_tools_halo_layer_05.cc        |   2 +-
 .../grid/grid_tools_halo_layer_ghost_cells.cc |  11 +-
 tests/grid/merge_triangulations_02.cc         |   2 +-
 tests/grid/merge_triangulations_03.cc         |   4 +-
 tests/grid/number_cache_01.cc                 |   2 +-
 tests/grid/number_cache_03.cc                 |   2 +-
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 tests/simplex/variable_face_quadratures_01.cc |  24 +-
 tests/simplex/variable_face_quadratures_02.cc |   4 +-
 tests/simplex/variable_face_quadratures_03.cc |  10 +-
 tests/simplex/wedge_01.cc                     |   2 +-
 tests/slepc/solve_01.cc                       |   4 +-
 tests/slepc/solve_04.cc                       |   4 +-
 tests/sparsity/block_dynamic_01.cc            |   8 +-
 ...ck_dynamic_sparsity_pattern_indexset_01.cc |  12 +-
 tests/sparsity/block_sparsity_pattern_03.cc   |   2 +-
 tests/sparsity/dynamic_sparsity_pattern_23.cc |   2 +-
 .../dynamic_sparsity_pattern_iterator_04.cc   |   2 +-
 tests/sparsity/sparsity_pattern.cc            |  12 +-
 tests/sundials/arkode_01.cc                   |   2 +-
 tests/sundials/arkode_02.cc                   |   2 +-
 tests/sundials/arkode_03.cc                   |   4 +-
 tests/sundials/arkode_04.cc                   |   2 +-
 tests/sundials/arkode_05.cc                   |   2 +-
 tests/sundials/arkode_06.cc                   |   2 +-
 tests/sundials/arkode_07.cc                   |   2 +-
 tests/sundials/arkode_08.cc                   |   2 +-
 tests/sundials/arkode_repeated_solve.cc       |   2 +-
 tests/sundials/ida_01.cc                      |   2 +-
 tests/sundials/ida_02.cc                      |   2 +-
 tests/sundials/kinsol_03.cc                   |   6 +-
 tests/sundials/kinsol_03_new_interface.cc     |   6 +-
 tests/sundials/kinsol_04.cc                   |   6 +-
 tests/sundials/kinsol_04_new_interface.cc     |   6 +-
 tests/sundials/kinsol_05.cc                   |   6 +-
 tests/sundials/kinsol_05_new_interface.cc     |   6 +-
 .../symengine_tensor_operations_03.cc         |   8 +-
 tests/tensors/constexpr_tensor.cc             |   2 +-
 tests/tensors/symmetric_tensor_28.cc          |   4 +-
 tests/tensors/symmetric_tensor_36.cc          |   4 +-
 tests/tensors/tensor_accessors_01.cc          |   2 +-
 tests/tensors/tensor_accessors_03.cc          |   2 +-
 tests/trilinos/add_matrices_05.cc             |   2 +-
 tests/trilinos/add_matrices_06.cc             |   8 +-
 .../trilinos/block_vector_move_operations.cc  |   4 +-
 tests/trilinos/copy_to_dealvec_block.cc       |   8 +-
 tests/trilinos/sparsity_pattern_06.cc         |   8 +-
 tests/trilinos/vector_move_operations.cc      |   4 +-
 tests/zoltan/zoltan_02.cc                     |   2 +-
 tests/zoltan/zoltan_03.cc                     |   2 +-
 tests/zoltan/zoltan_04.cc                     |   2 +-
 805 files changed, 2532 insertions(+), 2616 deletions(-)

diff --git a/examples/step-11/step-11.cc b/examples/step-11/step-11.cc
index 4333dcf50f..bec34be767 100644
--- a/examples/step-11/step-11.cc
+++ b/examples/step-11/step-11.cc
@@ -111,7 +111,7 @@ namespace Step11
     , dof_handler(triangulation)
     , mapping(mapping_degree)
   {
-    std::cout << "Using mapping with degree " << mapping_degree << ":"
+    std::cout << "Using mapping with degree " << mapping_degree << ':'
               << std::endl
               << "============================" << std::endl;
   }
diff --git a/examples/step-12/step-12.cc b/examples/step-12/step-12.cc
index a2ab5750bf..62712d43fd 100644
--- a/examples/step-12/step-12.cc
+++ b/examples/step-12/step-12.cc
@@ -543,7 +543,7 @@ namespace Step12
   void AdvectionProblem<dim>::output_results(const unsigned int cycle) const
   {
     const std::string filename = "solution-" + std::to_string(cycle) + ".vtk";
-    std::cout << "  Writing solution to <" << filename << ">" << std::endl;
+    std::cout << "  Writing solution to <" << filename << '>' << std::endl;
     std::ofstream output(filename);
 
     DataOut<dim> data_out;
diff --git a/examples/step-12b/step-12b.cc b/examples/step-12b/step-12b.cc
index aa717e06d9..ded1a32cd3 100644
--- a/examples/step-12b/step-12b.cc
+++ b/examples/step-12b/step-12b.cc
@@ -575,7 +575,7 @@ namespace Step12
     // First write the grid in eps format.
     {
       const std::string filename = "grid-" + std::to_string(cycle) + ".eps";
-      deallog << "Writing grid to <" << filename << ">" << std::endl;
+      deallog << "Writing grid to <" << filename << '>' << std::endl;
       std::ofstream eps_output(filename);
 
       GridOut grid_out;
@@ -585,7 +585,7 @@ namespace Step12
     // Then output the solution in gnuplot format.
     {
       const std::string filename = "sol-" + std::to_string(cycle) + ".gnuplot";
-      deallog << "Writing solution to <" << filename << ">" << std::endl;
+      deallog << "Writing solution to <" << filename << '>' << std::endl;
       std::ofstream gnuplot_output(filename);
 
       DataOut<dim> data_out;
diff --git a/examples/step-13/step-13.cc b/examples/step-13/step-13.cc
index 9b1617ff23..61cb734d51 100644
--- a/examples/step-13/step-13.cc
+++ b/examples/step-13/step-13.cc
@@ -1299,7 +1299,7 @@ namespace Step13
         // iteration. Note that the <code>std::flush</code> is needed to have
         // the text actually appear on the screen, rather than only in some
         // buffer that is only flushed the next time we issue an end-line.
-        std::cout << step << " " << std::flush;
+        std::cout << step << ' ' << std::flush;
 
         // Now solve the problem on the present grid, and run the evaluators
         // on it. The long type name of iterators into the list is a little
diff --git a/examples/step-17/step-17.cc b/examples/step-17/step-17.cc
index 838013b723..8ed50612fa 100644
--- a/examples/step-17/step-17.cc
+++ b/examples/step-17/step-17.cc
@@ -979,7 +979,7 @@ namespace Step17
           pcout << (p == 0 ? ' ' : '+')
                 << (DoFTools::count_dofs_with_subdomain_association(dof_handler,
                                                                     p));
-        pcout << ")" << std::endl;
+        pcout << ')' << std::endl;
 
         assemble_system();
         const unsigned int n_iterations = solve();
diff --git a/examples/step-18/step-18.cc b/examples/step-18/step-18.cc
index 1b491be1be..ba907366d1 100644
--- a/examples/step-18/step-18.cc
+++ b/examples/step-18/step-18.cc
@@ -1314,7 +1314,7 @@ namespace Step18
           pcout << (p == 0 ? ' ' : '+')
                 << (GridTools::count_cells_with_subdomain_association(
                      triangulation, p));
-        pcout << ")" << std::endl;
+        pcout << ')' << std::endl;
 
         setup_system();
 
@@ -1324,7 +1324,7 @@ namespace Step18
           pcout << (p == 0 ? ' ' : '+')
                 << (DoFTools::count_dofs_with_subdomain_association(dof_handler,
                                                                     p));
-        pcout << ")" << std::endl;
+        pcout << ')' << std::endl;
 
         solve_timestep();
       }
diff --git a/examples/step-24/step-24.cc b/examples/step-24/step-24.cc
index 891551ff15..b9d15add26 100644
--- a/examples/step-24/step-24.cc
+++ b/examples/step-24/step-24.cc
@@ -509,11 +509,11 @@ namespace Step24
 
         detector_data << time;
         for (unsigned int i = 0; i < detector_locations.size(); ++i)
-          detector_data << " "
+          detector_data << ' '
                         << VectorTools::point_value(dof_handler,
                                                     solution_p,
                                                     detector_locations[i])
-                        << " ";
+                        << ' ';
         detector_data << std::endl;
 
         old_solution_p = solution_p;
diff --git a/examples/step-28/step-28.cc b/examples/step-28/step-28.cc
index 1fa4205d50..205579d352 100644
--- a/examples/step-28/step-28.cc
+++ b/examples/step-28/step-28.cc
@@ -1663,9 +1663,9 @@ namespace Step28
             ++iteration;
           }
         while ((error > parameters.convergence_tolerance) && (iteration < 500));
-        convergence_table_stream << cycle << " " << energy_groups[0]->n_dofs()
-                                 << " " << energy_groups[1]->n_dofs() << " "
-                                 << k_eff << " "
+        convergence_table_stream << cycle << ' ' << energy_groups[0]->n_dofs()
+                                 << ' ' << energy_groups[1]->n_dofs() << ' '
+                                 << k_eff << ' '
                                  << energy_groups[0]->solution.linfty_norm() /
                                       energy_groups[1]->solution.linfty_norm()
                                  << '\n';
diff --git a/examples/step-35/step-35.cc b/examples/step-35/step-35.cc
index bee2871a98..d4fa04c223 100644
--- a/examples/step-35/step-35.cc
+++ b/examples/step-35/step-35.cc
@@ -492,7 +492,7 @@ namespace Step35
                    double,
                    << " The time step " << arg1 << " is out of range."
                    << std::endl
-                   << " The permitted range is (0," << arg2 << "]");
+                   << " The permitted range is (0," << arg2 << ']');
 
     void create_triangulation_and_dofs(const unsigned int n_refines);
 
diff --git a/examples/step-36/step-36.cc b/examples/step-36/step-36.cc
index 8c488d1a35..9a0c780514 100644
--- a/examples/step-36/step-36.cc
+++ b/examples/step-36/step-36.cc
@@ -324,9 +324,9 @@ namespace Step36
           max_spurious_eigenvalue = std::max(max_spurious_eigenvalue, ev);
         }
 
-    std::cout << "   Spurious eigenvalues are all in the interval "
-              << "[" << min_spurious_eigenvalue << ","
-              << max_spurious_eigenvalue << "]" << std::endl;
+    std::cout << "   Spurious eigenvalues are all in the interval " << '['
+              << min_spurious_eigenvalue << ',' << max_spurious_eigenvalue
+              << ']' << std::endl;
   }
 
 
diff --git a/examples/step-37/step-37.cc b/examples/step-37/step-37.cc
index 96564bd950..134fca1880 100644
--- a/examples/step-37/step-37.cc
+++ b/examples/step-37/step-37.cc
@@ -803,7 +803,7 @@ namespace Step37
     constraints.close();
     setup_time += time.wall_time();
     time_details << "Distribute DoFs & B.C.     (CPU/wall) " << time.cpu_time()
-                 << "s/" << time.wall_time() << "s" << std::endl;
+                 << "s/" << time.wall_time() << 's' << std::endl;
     time.restart();
 
     {
@@ -829,7 +829,7 @@ namespace Step37
 
     setup_time += time.wall_time();
     time_details << "Setup matrix-free system   (CPU/wall) " << time.cpu_time()
-                 << "s/" << time.wall_time() << "s" << std::endl;
+                 << "s/" << time.wall_time() << 's' << std::endl;
     time.restart();
 
     // Next, initialize the matrices for the multigrid method on all the
@@ -883,7 +883,7 @@ namespace Step37
       }
     setup_time += time.wall_time();
     time_details << "Setup matrix-free levels   (CPU/wall) " << time.cpu_time()
-                 << "s/" << time.wall_time() << "s" << std::endl;
+                 << "s/" << time.wall_time() << 's' << std::endl;
   }
 
 
@@ -920,7 +920,7 @@ namespace Step37
 
     setup_time += time.wall_time();
     time_details << "Assemble right hand side   (CPU/wall) " << time.cpu_time()
-                 << "s/" << time.wall_time() << "s" << std::endl;
+                 << "s/" << time.wall_time() << 's' << std::endl;
   }
 
 
@@ -1159,7 +1159,7 @@ namespace Step37
 
       pcout << "Vectorization over " << n_vect_doubles
             << " doubles = " << n_vect_bits << " bits ("
-            << Utilities::System::get_current_vectorization_level() << ")"
+            << Utilities::System::get_current_vectorization_level() << ')'
             << std::endl;
     }
 
diff --git a/examples/step-42/step-42.cc b/examples/step-42/step-42.cc
index 3e9fdeaea0..5db3a410ba 100644
--- a/examples/step-42/step-42.cc
+++ b/examples/step-42/step-42.cc
@@ -469,7 +469,7 @@ namespace Step42
       hy = 1.0 / (ny - 1);
 
       if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
-        std::cout << "Read obstacle from file <" << name << ">" << std::endl
+        std::cout << "Read obstacle from file <" << name << '>' << std::endl
                   << "Resolution of the scanned obstacle picture: " << nx
                   << " x " << ny << std::endl;
     }
@@ -1716,7 +1716,7 @@ namespace Step42
                  !transfer_solution)
           constitutive_law.set_sigma_0(correct_sigma);
 
-        pcout << " " << std::endl;
+        pcout << ' ' << std::endl;
         pcout << "   Newton iteration " << newton_step << std::endl;
         pcout << "      Updating active set..." << std::endl;
 
@@ -2154,7 +2154,7 @@ namespace Step42
         Utilities::System::MemoryStats stats;
         Utilities::System::get_memory_stats(stats);
         pcout << "Peak virtual memory used, resident in kB: " << stats.VmSize
-              << " " << stats.VmRSS << std::endl;
+              << ' ' << stats.VmRSS << std::endl;
 
         if (base_mesh == "box")
           output_contact_force();
diff --git a/examples/step-44/step-44.cc b/examples/step-44/step-44.cc
index 082ddf6fed..40dd349253 100644
--- a/examples/step-44/step-44.cc
+++ b/examples/step-44/step-44.cc
@@ -1651,7 +1651,7 @@ namespace Step44
   {
     std::cout << std::endl
               << "Timestep " << time.get_timestep() << " @ " << time.current()
-              << "s" << std::endl;
+              << 's' << std::endl;
 
     BlockVector<double> newton_update(dofs_per_block);
 
@@ -1687,7 +1687,7 @@ namespace Step44
     unsigned int newton_iteration = 0;
     for (; newton_iteration < parameters.max_iterations_NR; ++newton_iteration)
       {
-        std::cout << " " << std::setw(2) << newton_iteration << " "
+        std::cout << ' ' << std::setw(2) << newton_iteration << ' '
                   << std::flush;
 
         // We construct the linear system, but hold off on solving it
@@ -1767,7 +1767,7 @@ namespace Step44
     static const unsigned int l_width = 150;
 
     for (unsigned int i = 0; i < l_width; ++i)
-      std::cout << "_";
+      std::cout << '_';
     std::cout << std::endl;
 
     std::cout << "               SOLVER STEP               "
@@ -1776,7 +1776,7 @@ namespace Step44
               << " NU_U       NU_P       NU_J " << std::endl;
 
     for (unsigned int i = 0; i < l_width; ++i)
-      std::cout << "_";
+      std::cout << '_';
     std::cout << std::endl;
   }
 
@@ -1788,7 +1788,7 @@ namespace Step44
     static const unsigned int l_width = 150;
 
     for (unsigned int i = 0; i < l_width; ++i)
-      std::cout << "_";
+      std::cout << '_';
     std::cout << std::endl;
 
     const std::pair<double, double> error_dil = get_error_dilation();
diff --git a/examples/step-48/step-48.cc b/examples/step-48/step-48.cc
index ad97c0b9b7..8daa6d4cc6 100644
--- a/examples/step-48/step-48.cc
+++ b/examples/step-48/step-48.cc
@@ -540,7 +540,7 @@ namespace Step48
       const unsigned int n_vect_bits    = 8 * sizeof(double) * n_vect_doubles;
       pcout << "Vectorization over " << n_vect_doubles
             << " doubles = " << n_vect_bits << " bits ("
-            << Utilities::System::get_current_vectorization_level() << ")"
+            << Utilities::System::get_current_vectorization_level() << ')'
             << std::endl
             << std::endl;
     }
@@ -630,7 +630,7 @@ namespace Step48
           << "   Performed " << timestep_number << " time steps." << std::endl;
 
     pcout << "   Average wallclock time per time step: "
-          << wtime / timestep_number << "s" << std::endl;
+          << wtime / timestep_number << 's' << std::endl;
 
     pcout << "   Spent " << output_time << "s on output and " << wtime
           << "s on computations." << std::endl;
diff --git a/examples/step-49/step-49.cc b/examples/step-49/step-49.cc
index 0fff1d2139..3f926423cf 100644
--- a/examples/step-49/step-49.cc
+++ b/examples/step-49/step-49.cc
@@ -80,7 +80,7 @@ void print_mesh_info(const Triangulation<dim> &triangulation,
     for (const std::pair<const types::boundary_id, unsigned int> &pair :
          boundary_count)
       {
-        std::cout << pair.first << "(" << pair.second << " times) ";
+        std::cout << pair.first << '(' << pair.second << " times) ";
       }
     std::cout << std::endl;
   }
diff --git a/examples/step-57/step-57.cc b/examples/step-57/step-57.cc
index 2ffc4d98cd..2d67c9d9a9 100644
--- a/examples/step-57/step-57.cc
+++ b/examples/step-57/step-57.cc
@@ -787,7 +787,7 @@ namespace Step57
         f << p(dim - 1);
 
         for (int j = 0; j < dim; ++j)
-          f << " " << tmp_vector(j);
+          f << ' ' << tmp_vector(j);
         f << std::endl;
       }
   }
diff --git a/examples/step-66/step-66.cc b/examples/step-66/step-66.cc
index 323be0ad0e..155f7253ca 100644
--- a/examples/step-66/step-66.cc
+++ b/examples/step-66/step-66.cc
@@ -1127,7 +1127,7 @@ namespace Step66
 
 
         timer.stop();
-        pcout << "Time for setup+solve (CPU/Wall) " << timer.cpu_time() << "/"
+        pcout << "Time for setup+solve (CPU/Wall) " << timer.cpu_time() << '/'
               << timer.wall_time() << " s" << std::endl;
         pcout << std::endl;
 
diff --git a/examples/step-67/step-67.cc b/examples/step-67/step-67.cc
index ed06de80d8..b80cd368fd 100644
--- a/examples/step-67/step-67.cc
+++ b/examples/step-67/step-67.cc
@@ -2194,10 +2194,10 @@ namespace Euler_DG
       pcout << "Running with "
             << Utilities::MPI::n_mpi_processes(MPI_COMM_WORLD)
             << " MPI processes" << std::endl;
-      pcout << "Vectorization over " << n_vect_number << " "
+      pcout << "Vectorization over " << n_vect_number << ' '
             << (std::is_same<Number, double>::value ? "doubles" : "floats")
             << " = " << n_vect_bits << " bits ("
-            << Utilities::System::get_current_vectorization_level() << ")"
+            << Utilities::System::get_current_vectorization_level() << ')'
             << std::endl;
     }
 
diff --git a/examples/step-68/step-68.cc b/examples/step-68/step-68.cc
index 2b9efafe70..1dd1d6d05a 100644
--- a/examples/step-68/step-68.cc
+++ b/examples/step-68/step-68.cc
@@ -634,7 +634,7 @@ namespace Step68
                                   "interpolated-particles" :
                                   "analytical-particles");
 
-    pcout << "Writing particle output file: " << file_name << "-" << it
+    pcout << "Writing particle output file: " << file_name << '-' << it
           << std::endl;
 
     particle_output.write_vtu_with_pvtu_record(
@@ -669,7 +669,7 @@ namespace Step68
     const std::string output_folder(par.output_directory);
     const std::string file_name("background");
 
-    pcout << "Writing background field file: " << file_name << "-" << it
+    pcout << "Writing background field file: " << file_name << '-' << it
           << std::endl;
 
     data_out.write_vtu_with_pvtu_record(
diff --git a/examples/step-69/step-69.cc b/examples/step-69/step-69.cc
index 4a801f97ba..29683071bf 100644
--- a/examples/step-69/step-69.cc
+++ b/examples/step-69/step-69.cc
@@ -2618,7 +2618,7 @@ namespace Step69
   typename MainLoop<dim>::vector_type
   MainLoop<dim>::interpolate_initial_values(const double t)
   {
-    pcout << "MainLoop<dim>::interpolate_initial_values(t = " << t << ")"
+    pcout << "MainLoop<dim>::interpolate_initial_values(t = " << t << ')'
           << std::endl;
     TimerOutput::Scope scope(computing_timer,
                              "main_loop - setup scratch space");
@@ -2708,7 +2708,7 @@ namespace Step69
                              const double                               t,
                              const unsigned int                         cycle)
   {
-    pcout << "MainLoop<dim>::output(t = " << t << ")" << std::endl;
+    pcout << "MainLoop<dim>::output(t = " << t << ')' << std::endl;
 
     // If the asynchronous writeback option is set we launch a background
     // thread performing all the slow IO to disc. In that case we have to
diff --git a/examples/step-75/step-75.cc b/examples/step-75/step-75.cc
index 7385bb6722..1ed9c2d60a 100644
--- a/examples/step-75/step-75.cc
+++ b/examples/step-75/step-75.cc
@@ -1209,7 +1209,7 @@ namespace Step75
       pcout << "   Frequencies of poly. degrees:";
       for (unsigned int i = 0; i < fe_collection.size(); ++i)
         if (n_fe_indices[i] > 0)
-          pcout << ' ' << fe_collection[i].degree << ":" << n_fe_indices[i];
+          pcout << ' ' << fe_collection[i].degree << ':' << n_fe_indices[i];
       pcout << std::endl;
     }
   }
diff --git a/examples/step-76/step-76.cc b/examples/step-76/step-76.cc
index dd437c1867..161257e241 100644
--- a/examples/step-76/step-76.cc
+++ b/examples/step-76/step-76.cc
@@ -1522,10 +1522,10 @@ namespace Euler_DG
       pcout << "Running with "
             << Utilities::MPI::n_mpi_processes(MPI_COMM_WORLD)
             << " MPI processes" << std::endl;
-      pcout << "Vectorization over " << n_vect_number << " "
+      pcout << "Vectorization over " << n_vect_number << ' '
             << (std::is_same<Number, double>::value ? "doubles" : "floats")
             << " = " << n_vect_bits << " bits ("
-            << Utilities::System::get_current_vectorization_level() << ")"
+            << Utilities::System::get_current_vectorization_level() << ')'
             << std::endl;
     }
 
diff --git a/examples/step-79/step-79.cc b/examples/step-79/step-79.cc
index ec17414ef2..4c502426d6 100644
--- a/examples/step-79/step-79.cc
+++ b/examples/step-79/step-79.cc
@@ -1970,100 +1970,100 @@ namespace SAND
             if (is_right_handed_cell)
               {
                 /* Write one side at z = 0. */
-                stlfile << "   facet normal " << 0.000000e+00 << " "
-                        << 0.000000e+00 << " " << -1.000000e+00 << '\n';
+                stlfile << "   facet normal " << 0.000000e+00 << ' '
+                        << 0.000000e+00 << ' ' << -1.000000e+00 << '\n';
                 stlfile << "      outer loop\n";
-                stlfile << "         vertex " << cell->vertex(0)[0] << " "
-                        << cell->vertex(0)[1] << " " << 0.000000e+00 << '\n';
-                stlfile << "         vertex " << cell->vertex(2)[0] << " "
-                        << cell->vertex(2)[1] << " " << 0.000000e+00 << '\n';
-                stlfile << "         vertex " << cell->vertex(1)[0] << " "
-                        << cell->vertex(1)[1] << " " << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(0)[0] << ' '
+                        << cell->vertex(0)[1] << ' ' << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(2)[0] << ' '
+                        << cell->vertex(2)[1] << ' ' << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(1)[0] << ' '
+                        << cell->vertex(1)[1] << ' ' << 0.000000e+00 << '\n';
                 stlfile << "      endloop\n";
                 stlfile << "   endfacet\n";
-                stlfile << "   facet normal " << 0.000000e+00 << " "
-                        << 0.000000e+00 << " " << -1.000000e+00 << '\n';
+                stlfile << "   facet normal " << 0.000000e+00 << ' '
+                        << 0.000000e+00 << ' ' << -1.000000e+00 << '\n';
                 stlfile << "      outer loop\n";
-                stlfile << "         vertex " << cell->vertex(1)[0] << " "
-                        << cell->vertex(1)[1] << " " << 0.000000e+00 << '\n';
-                stlfile << "         vertex " << cell->vertex(2)[0] << " "
-                        << cell->vertex(2)[1] << " " << 0.000000e+00 << '\n';
-                stlfile << "         vertex " << cell->vertex(3)[0] << " "
-                        << cell->vertex(3)[1] << " " << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(1)[0] << ' '
+                        << cell->vertex(1)[1] << ' ' << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(2)[0] << ' '
+                        << cell->vertex(2)[1] << ' ' << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(3)[0] << ' '
+                        << cell->vertex(3)[1] << ' ' << 0.000000e+00 << '\n';
                 stlfile << "      endloop\n";
                 stlfile << "   endfacet\n";
 
                 /* Write one side at z = height. */
-                stlfile << "   facet normal " << 0.000000e+00 << " "
-                        << 0.000000e+00 << " " << 1.000000e+00 << '\n';
+                stlfile << "   facet normal " << 0.000000e+00 << ' '
+                        << 0.000000e+00 << ' ' << 1.000000e+00 << '\n';
                 stlfile << "      outer loop\n";
-                stlfile << "         vertex " << cell->vertex(0)[0] << " "
-                        << cell->vertex(0)[1] << " " << height << '\n';
-                stlfile << "         vertex " << cell->vertex(1)[0] << " "
-                        << cell->vertex(1)[1] << " " << height << '\n';
-                stlfile << "         vertex " << cell->vertex(2)[0] << " "
-                        << cell->vertex(2)[1] << " " << height << '\n';
+                stlfile << "         vertex " << cell->vertex(0)[0] << ' '
+                        << cell->vertex(0)[1] << ' ' << height << '\n';
+                stlfile << "         vertex " << cell->vertex(1)[0] << ' '
+                        << cell->vertex(1)[1] << ' ' << height << '\n';
+                stlfile << "         vertex " << cell->vertex(2)[0] << ' '
+                        << cell->vertex(2)[1] << ' ' << height << '\n';
                 stlfile << "      endloop\n";
                 stlfile << "   endfacet\n";
-                stlfile << "   facet normal " << 0.000000e+00 << " "
-                        << 0.000000e+00 << " " << 1.000000e+00 << '\n';
+                stlfile << "   facet normal " << 0.000000e+00 << ' '
+                        << 0.000000e+00 << ' ' << 1.000000e+00 << '\n';
                 stlfile << "      outer loop\n";
-                stlfile << "         vertex " << cell->vertex(1)[0] << " "
-                        << cell->vertex(1)[1] << " " << height << '\n';
-                stlfile << "         vertex " << cell->vertex(3)[0] << " "
-                        << cell->vertex(3)[1] << " " << height << '\n';
-                stlfile << "         vertex " << cell->vertex(2)[0] << " "
-                        << cell->vertex(2)[1] << " " << height << '\n';
+                stlfile << "         vertex " << cell->vertex(1)[0] << ' '
+                        << cell->vertex(1)[1] << ' ' << height << '\n';
+                stlfile << "         vertex " << cell->vertex(3)[0] << ' '
+                        << cell->vertex(3)[1] << ' ' << height << '\n';
+                stlfile << "         vertex " << cell->vertex(2)[0] << ' '
+                        << cell->vertex(2)[1] << ' ' << height << '\n';
                 stlfile << "      endloop\n";
                 stlfile << "   endfacet\n";
               }
             else /* The cell has a left-handed set up */
               {
                 /* Write one side at z = 0. */
-                stlfile << "   facet normal " << 0.000000e+00 << " "
-                        << 0.000000e+00 << " " << -1.000000e+00 << '\n';
+                stlfile << "   facet normal " << 0.000000e+00 << ' '
+                        << 0.000000e+00 << ' ' << -1.000000e+00 << '\n';
                 stlfile << "      outer loop\n";
-                stlfile << "         vertex " << cell->vertex(0)[0] << " "
-                        << cell->vertex(0)[1] << " " << 0.000000e+00 << '\n';
-                stlfile << "         vertex " << cell->vertex(1)[0] << " "
-                        << cell->vertex(1)[1] << " " << 0.000000e+00 << '\n';
-                stlfile << "         vertex " << cell->vertex(2)[0] << " "
-                        << cell->vertex(2)[1] << " " << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(0)[0] << ' '
+                        << cell->vertex(0)[1] << ' ' << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(1)[0] << ' '
+                        << cell->vertex(1)[1] << ' ' << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(2)[0] << ' '
+                        << cell->vertex(2)[1] << ' ' << 0.000000e+00 << '\n';
                 stlfile << "      endloop\n";
                 stlfile << "   endfacet\n";
-                stlfile << "   facet normal " << 0.000000e+00 << " "
-                        << 0.000000e+00 << " " << -1.000000e+00 << '\n';
+                stlfile << "   facet normal " << 0.000000e+00 << ' '
+                        << 0.000000e+00 << ' ' << -1.000000e+00 << '\n';
                 stlfile << "      outer loop\n";
-                stlfile << "         vertex " << cell->vertex(1)[0] << " "
-                        << cell->vertex(1)[1] << " " << 0.000000e+00 << '\n';
-                stlfile << "         vertex " << cell->vertex(3)[0] << " "
-                        << cell->vertex(3)[1] << " " << 0.000000e+00 << '\n';
-                stlfile << "         vertex " << cell->vertex(2)[0] << " "
-                        << cell->vertex(2)[1] << " " << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(1)[0] << ' '
+                        << cell->vertex(1)[1] << ' ' << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(3)[0] << ' '
+                        << cell->vertex(3)[1] << ' ' << 0.000000e+00 << '\n';
+                stlfile << "         vertex " << cell->vertex(2)[0] << ' '
+                        << cell->vertex(2)[1] << ' ' << 0.000000e+00 << '\n';
                 stlfile << "      endloop\n";
                 stlfile << "   endfacet\n";
 
                 /* Write one side at z = height. */
-                stlfile << "   facet normal " << 0.000000e+00 << " "
-                        << 0.000000e+00 << " " << 1.000000e+00 << '\n';
+                stlfile << "   facet normal " << 0.000000e+00 << ' '
+                        << 0.000000e+00 << ' ' << 1.000000e+00 << '\n';
                 stlfile << "      outer loop\n";
-                stlfile << "         vertex " << cell->vertex(0)[0] << " "
-                        << cell->vertex(0)[1] << " " << height << '\n';
-                stlfile << "         vertex " << cell->vertex(2)[0] << " "
-                        << cell->vertex(2)[1] << " " << height << '\n';
-                stlfile << "         vertex " << cell->vertex(1)[0] << " "
-                        << cell->vertex(1)[1] << " " << height << '\n';
+                stlfile << "         vertex " << cell->vertex(0)[0] << ' '
+                        << cell->vertex(0)[1] << ' ' << height << '\n';
+                stlfile << "         vertex " << cell->vertex(2)[0] << ' '
+                        << cell->vertex(2)[1] << ' ' << height << '\n';
+                stlfile << "         vertex " << cell->vertex(1)[0] << ' '
+                        << cell->vertex(1)[1] << ' ' << height << '\n';
                 stlfile << "      endloop\n";
                 stlfile << "   endfacet\n";
-                stlfile << "   facet normal " << 0.000000e+00 << " "
-                        << 0.000000e+00 << " " << 1.000000e+00 << '\n';
+                stlfile << "   facet normal " << 0.000000e+00 << ' '
+                        << 0.000000e+00 << ' ' << 1.000000e+00 << '\n';
                 stlfile << "      outer loop\n";
-                stlfile << "         vertex " << cell->vertex(1)[0] << " "
-                        << cell->vertex(1)[1] << " " << height << '\n';
-                stlfile << "         vertex " << cell->vertex(2)[0] << " "
-                        << cell->vertex(2)[1] << " " << height << '\n';
-                stlfile << "         vertex " << cell->vertex(3)[0] << " "
-                        << cell->vertex(3)[1] << " " << height << '\n';
+                stlfile << "         vertex " << cell->vertex(1)[0] << ' '
+                        << cell->vertex(1)[1] << ' ' << height << '\n';
+                stlfile << "         vertex " << cell->vertex(2)[0] << ' '
+                        << cell->vertex(2)[1] << ' ' << height << '\n';
+                stlfile << "         vertex " << cell->vertex(3)[0] << ' '
+                        << cell->vertex(3)[1] << ' ' << height << '\n';
                 stlfile << "      endloop\n";
                 stlfile << "   endfacet\n";
               }
@@ -2108,34 +2108,34 @@ namespace SAND
                         0)
                       {
                         stlfile << "   facet normal "
-                                << normal_vector[0] / normal_norm << " "
-                                << normal_vector[1] / normal_norm << " "
+                                << normal_vector[0] / normal_norm << ' '
+                                << normal_vector[1] / normal_norm << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "      outer loop\n";
                         stlfile << "         vertex " << face->vertex(0)[0]
-                                << " " << face->vertex(0)[1] << " "
+                                << ' ' << face->vertex(0)[1] << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "         vertex " << face->vertex(0)[0]
-                                << " " << face->vertex(0)[1] << " " << height
+                                << ' ' << face->vertex(0)[1] << ' ' << height
                                 << '\n';
                         stlfile << "         vertex " << face->vertex(1)[0]
-                                << " " << face->vertex(1)[1] << " "
+                                << ' ' << face->vertex(1)[1] << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "      endloop\n";
                         stlfile << "   endfacet\n";
                         stlfile << "   facet normal "
-                                << normal_vector[0] / normal_norm << " "
-                                << normal_vector[1] / normal_norm << " "
+                                << normal_vector[0] / normal_norm << ' '
+                                << normal_vector[1] / normal_norm << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "      outer loop\n";
                         stlfile << "         vertex " << face->vertex(0)[0]
-                                << " " << face->vertex(0)[1] << " " << height
+                                << ' ' << face->vertex(0)[1] << ' ' << height
                                 << '\n';
                         stlfile << "         vertex " << face->vertex(1)[0]
-                                << " " << face->vertex(1)[1] << " " << height
+                                << ' ' << face->vertex(1)[1] << ' ' << height
                                 << '\n';
                         stlfile << "         vertex " << face->vertex(1)[0]
-                                << " " << face->vertex(1)[1] << " "
+                                << ' ' << face->vertex(1)[1] << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "      endloop\n";
                         stlfile << "   endfacet\n";
@@ -2143,34 +2143,34 @@ namespace SAND
                     else
                       {
                         stlfile << "   facet normal "
-                                << normal_vector[0] / normal_norm << " "
-                                << normal_vector[1] / normal_norm << " "
+                                << normal_vector[0] / normal_norm << ' '
+                                << normal_vector[1] / normal_norm << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "      outer loop\n";
                         stlfile << "         vertex " << face->vertex(0)[0]
-                                << " " << face->vertex(0)[1] << " "
+                                << ' ' << face->vertex(0)[1] << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "         vertex " << face->vertex(1)[0]
-                                << " " << face->vertex(1)[1] << " "
+                                << ' ' << face->vertex(1)[1] << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "         vertex " << face->vertex(0)[0]
-                                << " " << face->vertex(0)[1] << " " << height
+                                << ' ' << face->vertex(0)[1] << ' ' << height
                                 << '\n';
                         stlfile << "      endloop\n";
                         stlfile << "   endfacet\n";
                         stlfile << "   facet normal "
-                                << normal_vector[0] / normal_norm << " "
-                                << normal_vector[1] / normal_norm << " "
+                                << normal_vector[0] / normal_norm << ' '
+                                << normal_vector[1] / normal_norm << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "      outer loop\n";
                         stlfile << "         vertex " << face->vertex(0)[0]
-                                << " " << face->vertex(0)[1] << " " << height
+                                << ' ' << face->vertex(0)[1] << ' ' << height
                                 << '\n';
                         stlfile << "         vertex " << face->vertex(1)[0]
-                                << " " << face->vertex(1)[1] << " "
+                                << ' ' << face->vertex(1)[1] << ' '
                                 << 0.000000e+00 << '\n';
                         stlfile << "         vertex " << face->vertex(1)[0]
-                                << " " << face->vertex(1)[1] << " " << height
+                                << ' ' << face->vertex(1)[1] << ' ' << height
                                 << '\n';
                         stlfile << "      endloop\n";
                         stlfile << "   endfacet\n";
diff --git a/include/deal.II/base/exceptions.h b/include/deal.II/base/exceptions.h
index 60eab6d9bd..7e1256db1c 100644
--- a/include/deal.II/base/exceptions.h
+++ b/include/deal.II/base/exceptions.h
@@ -884,7 +884,7 @@ namespace StandardExceptions
                  int,
                  int,
                  << "You are trying to execute functionality that is "
-                 << "impossible in dimensions <" << arg1 << "," << arg2
+                 << "impossible in dimensions <" << arg1 << ',' << arg2
                  << "> or simply does not make any sense.");
 
 
@@ -947,7 +947,7 @@ namespace StandardExceptions
     std::size_t,
     std::size_t,
     std::size_t,
-    << "Index " << arg1 << " is not in the half-open range [" << arg2 << ","
+    << "Index " << arg1 << " is not in the half-open range [" << arg2 << ','
     << arg3 << ")."
     << (arg2 == arg3 ?
           " In the current case, this half-open range is in fact empty, "
@@ -977,7 +977,7 @@ namespace StandardExceptions
     T,
     T,
     T,
-    << "Index " << arg1 << " is not in the half-open range [" << arg2 << ","
+    << "Index " << arg1 << " is not in the half-open range [" << arg2 << ','
     << arg3 << ")."
     << (arg2 == arg3 ?
           " In the current case, this half-open range is in fact empty, "
diff --git a/include/deal.II/base/function_cspline.h b/include/deal.II/base/function_cspline.h
index b518456162..766dfa7ef1 100644
--- a/include/deal.II/base/function_cspline.h
+++ b/include/deal.II/base/function_cspline.h
@@ -60,7 +60,7 @@ namespace Functions
     double,
     << "Spline function can not be evaluated outside of the interpolation range: "
     << std::endl
-    << arg1 << " is not in [" << arg2 << ";" << arg3 << "].");
+    << arg1 << " is not in [" << arg2 << ';' << arg3 << "].");
 
   /**
    * The cubic spline function using GNU Scientific Library.
diff --git a/include/deal.II/base/function_parser.h b/include/deal.II/base/function_parser.h
index 1bd70f3c2a..3e1e28f328 100644
--- a/include/deal.II/base/function_parser.h
+++ b/include/deal.II/base/function_parser.h
@@ -146,7 +146,7 @@ class Vector;
  * const double c = vector_function.value(point, 1);
  *
  * // Output the evaluated function
- * deallog << "Function '" << expressions[0] << "," << expressions[1] << "'"
+ * deallog << "Function '" << expressions[0] << ',' << expressions[1] << "'"
  *         << " at " << point
  *         << " is " << result << std::endl;
  * @endcode
diff --git a/include/deal.II/base/index_set.h b/include/deal.II/base/index_set.h
index 4cb5d98560..782ded80df 100644
--- a/include/deal.II/base/index_set.h
+++ b/include/deal.II/base/index_set.h
@@ -2020,19 +2020,19 @@ inline void
 IndexSet::print(StreamType &out) const
 {
   compress();
-  out << "{";
+  out << '{';
   std::vector<Range>::const_iterator p;
   for (p = ranges.begin(); p != ranges.end(); ++p)
     {
       if (p->end - p->begin == 1)
         out << p->begin;
       else
-        out << "[" << p->begin << "," << p->end - 1 << "]";
+        out << '[' << p->begin << ',' << p->end - 1 << ']';
 
       if (p != --ranges.end())
         out << ", ";
     }
-  out << "}" << std::endl;
+  out << '}' << std::endl;
 }
 
 
diff --git a/include/deal.II/base/polynomial_space.h b/include/deal.II/base/polynomial_space.h
index dad3fdf62d..dc1ac3dc81 100644
--- a/include/deal.II/base/polynomial_space.h
+++ b/include/deal.II/base/polynomial_space.h
@@ -322,7 +322,7 @@ PolynomialSpace<dim>::output_indices(StreamType &out) const
       const std::array<unsigned int, dim> ix = compute_index(i);
       out << i << "\t";
       for (unsigned int d = 0; d < dim; ++d)
-        out << ix[d] << " ";
+        out << ix[d] << ' ';
       out << std::endl;
     }
 }
diff --git a/include/deal.II/base/table.h b/include/deal.II/base/table.h
index b5ada3e8e8..286304f4f3 100644
--- a/include/deal.II/base/table.h
+++ b/include/deal.II/base/table.h
@@ -201,7 +201,7 @@ namespace internal
                      size_type,
                      size_type,
                      << "Index " << N - P + 1 << "has a value of " << arg1
-                     << " but needs to be in the range [" << arg2 << "," << arg3
+                     << " but needs to be in the range [" << arg2 << ',' << arg3
                      << "[.");
 
     private:
diff --git a/include/deal.II/base/table_handler.h b/include/deal.II/base/table_handler.h
index 30a828a04c..3b1c65d6d6 100644
--- a/include/deal.II/base/table_handler.h
+++ b/include/deal.II/base/table_handler.h
@@ -617,7 +617,7 @@ public:
    */
   DeclException1(ExcUndefinedTexFormat,
                  std::string,
-                 << "<" << arg1 << "> is not a tex column format. Use "
+                 << '<' << arg1 << "> is not a tex column format. Use "
                  << "'l', 'c', or 'r' to indicate left, centered, or "
                  << "right aligned text.");
   //@}
diff --git a/include/deal.II/base/tensor_function_parser.h b/include/deal.II/base/tensor_function_parser.h
index 0632e3e946..2a33e24aee 100644
--- a/include/deal.II/base/tensor_function_parser.h
+++ b/include/deal.II/base/tensor_function_parser.h
@@ -82,8 +82,8 @@ class Vector;
  *         << " @ " << point
  *         << " is: "
  *         << std::endl
- *         << result[0][0] << " " << result[0][1] << std::endl
- *         << result[1][0] << " " << result[1][1]
+ *         << result[0][0] << ' ' << result[0][1] << std::endl
+ *         << result[1][0] << ' ' << result[1][1]
  *         << std::endl;
  * @endcode
  *
diff --git a/include/deal.II/dofs/dof_tools.h b/include/deal.II/dofs/dof_tools.h
index 5ddc42c47d..ac7fd4621b 100644
--- a/include/deal.II/dofs/dof_tools.h
+++ b/include/deal.II/dofs/dof_tools.h
@@ -2400,7 +2400,7 @@ namespace DoFTools
    *     << "'-' with labels point pt 2 offset 1,1"
    *     << std::endl;
    * GridOut().write_gnuplot (triangulation, out);
-   * out << "e" << std::endl;
+   * out << 'e' << std::endl;
    *
    * std::map<types::global_dof_index, Point<dim> > support_points;
    * DoFTools::map_dofs_to_support_points (MappingQ1<dim>(),
@@ -2408,7 +2408,7 @@ namespace DoFTools
    *                                       support_points);
    * DoFTools::write_gnuplot_dof_support_point_info(out,
    *                                                support_points);
-   * out << "e" << std::endl;
+   * out << 'e' << std::endl;
    * @endcode
    * and from within gnuplot execute the following command:
    * @code
@@ -2432,7 +2432,7 @@ namespace DoFTools
    *     << "'-' with labels point pt 2 offset 1,1 notitle"
    *     << std::endl;
    * GridOut().write_gnuplot (triangulation, out);
-   * out << "e" << std::endl;
+   * out << 'e' << std::endl;
    *
    * std::map<types::global_dof_index, Point<dim> > support_points;
    * DoFTools::map_dofs_to_support_points (MappingQ1<dim>(),
@@ -2440,7 +2440,7 @@ namespace DoFTools
    *                                       support_points);
    * DoFTools::write_gnuplot_dof_support_point_info(out,
    *                                                support_points);
-   * out << "e" << std::endl;
+   * out << 'e' << std::endl;
    * @endcode
    */
   template <int spacedim>
diff --git a/include/deal.II/fe/fe.h b/include/deal.II/fe/fe.h
index e6bd24c129..624b7a244f 100644
--- a/include/deal.II/fe/fe.h
+++ b/include/deal.II/fe/fe.h
@@ -2369,7 +2369,7 @@ public:
   DeclException2(ExcWrongInterfaceMatrixSize,
                  int,
                  int,
-                 << "The interface matrix has a size of " << arg1 << "x" << arg2
+                 << "The interface matrix has a size of " << arg1 << 'x' << arg2
                  << ", which is not reasonable for the current element "
                     "in the present dimension.");
   /**
diff --git a/include/deal.II/fe/fe_dg_vector.templates.h b/include/deal.II/fe/fe_dg_vector.templates.h
index 6f6b08e4b8..d61b90c8ea 100644
--- a/include/deal.II/fe/fe_dg_vector.templates.h
+++ b/include/deal.II/fe/fe_dg_vector.templates.h
@@ -70,8 +70,8 @@ std::string
 FE_DGVector<PolynomialType, dim, spacedim>::get_name() const
 {
   std::ostringstream namebuf;
-  namebuf << "FE_DGVector_" << this->poly_space->name() << "<" << dim << ">("
-          << this->degree - 1 << ")";
+  namebuf << "FE_DGVector_" << this->poly_space->name() << '<' << dim << ">("
+          << this->degree - 1 << ')';
   return namebuf.str();
 }
 
diff --git a/include/deal.II/fe/fe_tools.h b/include/deal.II/fe/fe_tools.h
index 93140fd40b..280949112d 100644
--- a/include/deal.II/fe/fe_tools.h
+++ b/include/deal.II/fe/fe_tools.h
@@ -1364,8 +1364,8 @@ namespace FETools
                  int,
                  int,
                  int,
-                 << "This is a " << arg1 << "x" << arg2 << " matrix, "
-                 << "but should be a " << arg3 << "x" << arg4 << " matrix.");
+                 << "This is a " << arg1 << 'x' << arg2 << " matrix, "
+                 << "but should be a " << arg3 << 'x' << arg4 << " matrix.");
 
   /**
    * Exception thrown if an embedding matrix was computed inaccurately.
diff --git a/include/deal.II/grid/reference_cell.h b/include/deal.II/grid/reference_cell.h
index 4917603997..53beb6fb7b 100644
--- a/include/deal.II/grid/reference_cell.h
+++ b/include/deal.II/grid/reference_cell.h
@@ -2063,7 +2063,7 @@ namespace internal
     virtual void
     print_info(std::ostream &out) const override
     {
-      out << "[";
+      out << '[';
 
       const unsigned int n_vertices = entity_type.n_vertices();
 
@@ -2071,7 +2071,7 @@ namespace internal
         {
           out << vertices_0[i];
           if (i + 1 != n_vertices)
-            out << ",";
+            out << ',';
         }
 
       out << "] is not a permutation of [";
@@ -2080,7 +2080,7 @@ namespace internal
         {
           out << vertices_1[i];
           if (i + 1 != n_vertices)
-            out << ",";
+            out << ',';
         }
 
       out << "]." << std::endl;
diff --git a/include/deal.II/lac/affine_constraints.templates.h b/include/deal.II/lac/affine_constraints.templates.h
index fdcadc83c9..e12b30cc99 100644
--- a/include/deal.II/lac/affine_constraints.templates.h
+++ b/include/deal.II/lac/affine_constraints.templates.h
@@ -1241,7 +1241,7 @@ AffineConstraints<number>::print(std::ostream &out) const
       if (line.entries.size() > 0)
         {
           for (const std::pair<size_type, number> &entry : line.entries)
-            out << "    " << line.index << " " << entry.first << ":  "
+            out << "    " << line.index << ' ' << entry.first << ":  "
                 << entry.second << '\n';
 
           // print out inhomogeneity.
@@ -1280,7 +1280,7 @@ AffineConstraints<number>::write_dot(std::ostream &out) const
       else
         out << "  " << lines[i].index << '\n';
     }
-  out << "}" << std::endl;
+  out << '}' << std::endl;
 }
 
 
diff --git a/include/deal.II/lac/block_matrix_base.h b/include/deal.II/lac/block_matrix_base.h
index 4b97046f8b..7561c8447d 100644
--- a/include/deal.II/lac/block_matrix_base.h
+++ b/include/deal.II/lac/block_matrix_base.h
@@ -2510,7 +2510,7 @@ BlockMatrixBase<MatrixType>::print(std::ostream &out,
     for (unsigned int col = 0; col < n_block_cols(); ++col)
       {
         if (!alternative_output)
-          out << "Block (" << row << ", " << col << ")" << std::endl;
+          out << "Block (" << row << ", " << col << ')' << std::endl;
 
         block(row, col).print(out, alternative_output);
       }
diff --git a/include/deal.II/lac/block_sparse_matrix.templates.h b/include/deal.II/lac/block_sparse_matrix.templates.h
index abc833a2f3..5826a30857 100644
--- a/include/deal.II/lac/block_sparse_matrix.templates.h
+++ b/include/deal.II/lac/block_sparse_matrix.templates.h
@@ -183,7 +183,7 @@ BlockSparseMatrix<number>::print_formatted(std::ostream &     out,
   for (size_type r = 0; r < this->n_block_rows(); ++r)
     for (size_type c = 0; c < this->n_block_cols(); ++c)
       {
-        out << "Component (" << r << "," << c << ")" << std::endl;
+        out << "Component (" << r << ',' << c << ')' << std::endl;
         this->block(r, c).print_formatted(
           out, precision, scientific, width, zero_string, denominator);
       }
diff --git a/include/deal.II/lac/cuda_sparse_matrix.h b/include/deal.II/lac/cuda_sparse_matrix.h
index 54244dd937..f1598c54ff 100644
--- a/include/deal.II/lac/cuda_sparse_matrix.h
+++ b/include/deal.II/lac/cuda_sparse_matrix.h
@@ -451,7 +451,7 @@ namespace CUDAWrappers
             if (across)
               out << ' ' << i << ',' << cols[j] << ':' << val[j];
             else
-              out << "(" << i << "," << cols[j] << ") " << val[j] << std::endl;
+              out << '(' << i << ',' << cols[j] << ") " << val[j] << std::endl;
           }
       }
     if (across)
diff --git a/include/deal.II/lac/la_parallel_vector.h b/include/deal.II/lac/la_parallel_vector.h
index 15988bdc09..45b0d6cffa 100644
--- a/include/deal.II/lac/la_parallel_vector.h
+++ b/include/deal.II/lac/la_parallel_vector.h
@@ -1258,7 +1258,7 @@ namespace LinearAlgebra
         << "You tried to access element " << arg1
         << " of a distributed vector, but this element is not "
         << "stored on the current processor. Note: The range of "
-        << "locally owned elements is [" << arg2 << "," << arg3
+        << "locally owned elements is [" << arg2 << ',' << arg3
         << "], and there are " << arg4 << " ghost elements "
         << "that this vector can access."
         << "\n\n"
diff --git a/include/deal.II/lac/la_parallel_vector.templates.h b/include/deal.II/lac/la_parallel_vector.templates.h
index 3854487284..b9c8b290af 100644
--- a/include/deal.II/lac/la_parallel_vector.templates.h
+++ b/include/deal.II/lac/la_parallel_vector.templates.h
@@ -2164,7 +2164,7 @@ namespace LinearAlgebra
               out << '(' << partitioner->ghost_indices().nth_index_in_set(i)
                   << '/'
                   << stored_elements[partitioner->locally_owned_size() + i]
-                  << ")" << std::endl;
+                  << ')' << std::endl;
           out << std::endl;
         }
       out << std::flush;
diff --git a/include/deal.II/lac/petsc_vector_base.h b/include/deal.II/lac/petsc_vector_base.h
index b628221681..cdc19ab169 100644
--- a/include/deal.II/lac/petsc_vector_base.h
+++ b/include/deal.II/lac/petsc_vector_base.h
@@ -180,7 +180,7 @@ namespace PETScWrappers
         int,
         << "You tried to access element " << arg1
         << " of a distributed vector, but only elements in range [" << arg2
-        << "," << arg3 << "] are stored locally and can be accessed."
+        << ',' << arg3 << "] are stored locally and can be accessed."
         << "\n\n"
         << "A common source for this kind of problem is that you "
         << "are passing a 'fully distributed' vector into a function "
diff --git a/include/deal.II/lac/read_write_vector.templates.h b/include/deal.II/lac/read_write_vector.templates.h
index e4ab936834..ddd422fa9d 100644
--- a/include/deal.II/lac/read_write_vector.templates.h
+++ b/include/deal.II/lac/read_write_vector.templates.h
@@ -1027,7 +1027,7 @@ namespace LinearAlgebra
     out << std::endl;
     unsigned int i = 0;
     for (const auto idx : this->stored_elements)
-      out << "[" << idx << "]: " << values[i++] << '\n';
+      out << '[' << idx << "]: " << values[i++] << '\n';
     out << std::flush;
 
     AssertThrow(out, ExcIO());
diff --git a/include/deal.II/lac/sparse_matrix.h b/include/deal.II/lac/sparse_matrix.h
index d2c5f619b0..b01eaa60f3 100644
--- a/include/deal.II/lac/sparse_matrix.h
+++ b/include/deal.II/lac/sparse_matrix.h
@@ -2543,7 +2543,7 @@ SparseMatrix<number>::print(StreamType &out,
               if (across)
                 out << ' ' << i << ',' << cols->colnums[j] << ':' << val[j];
               else
-                out << "(" << i << "," << cols->colnums[j] << ") " << val[j]
+                out << '(' << i << ',' << cols->colnums[j] << ") " << val[j]
                     << std::endl;
             }
         }
diff --git a/include/deal.II/lac/sparse_mic.h b/include/deal.II/lac/sparse_mic.h
index 6043b7c738..46eff79568 100644
--- a/include/deal.II/lac/sparse_mic.h
+++ b/include/deal.II/lac/sparse_mic.h
@@ -147,7 +147,7 @@ public:
   DeclException2(ExcDecompositionNotStable,
                  int,
                  double,
-                 << "The diagonal element (" << arg1 << "," << arg1 << ") is "
+                 << "The diagonal element (" << arg1 << ',' << arg1 << ") is "
                  << arg2 << ", but must be positive");
 
   //@}
diff --git a/include/deal.II/lac/trilinos_sparse_matrix.h b/include/deal.II/lac/trilinos_sparse_matrix.h
index 68bcac534b..8eec00f32d 100644
--- a/include/deal.II/lac/trilinos_sparse_matrix.h
+++ b/include/deal.II/lac/trilinos_sparse_matrix.h
@@ -1885,10 +1885,10 @@ namespace TrilinosWrappers
                    size_type,
                    size_type,
                    size_type,
-                   << "You tried to access element (" << arg1 << "/" << arg2
-                   << ")"
+                   << "You tried to access element (" << arg1 << '/' << arg2
+                   << ')'
                    << " of a distributed matrix, but only rows in range ["
-                   << arg3 << "," << arg4
+                   << arg3 << ',' << arg4
                    << "] are stored locally and can be accessed.");
 
     /**
@@ -1897,9 +1897,8 @@ namespace TrilinosWrappers
     DeclException2(ExcAccessToNonPresentElement,
                    size_type,
                    size_type,
-                   << "You tried to access element (" << arg1 << "/" << arg2
-                   << ")"
-                   << " of a sparse matrix, but it appears to not"
+                   << "You tried to access element (" << arg1 << '/' << arg2
+                   << ')' << " of a sparse matrix, but it appears to not"
                    << " exist in the Trilinos sparsity pattern.");
     //@}
 
diff --git a/include/deal.II/lac/trilinos_sparsity_pattern.h b/include/deal.II/lac/trilinos_sparsity_pattern.h
index 80c733e1bc..eebc438d45 100644
--- a/include/deal.II/lac/trilinos_sparsity_pattern.h
+++ b/include/deal.II/lac/trilinos_sparsity_pattern.h
@@ -965,10 +965,10 @@ namespace TrilinosWrappers
                    size_type,
                    size_type,
                    size_type,
-                   << "You tried to access element (" << arg1 << "/" << arg2
-                   << ")"
+                   << "You tried to access element (" << arg1 << '/' << arg2
+                   << ')'
                    << " of a distributed matrix, but only rows in range ["
-                   << arg3 << "," << arg4
+                   << arg3 << ',' << arg4
                    << "] are stored locally and can be accessed.");
 
     /**
@@ -977,9 +977,8 @@ namespace TrilinosWrappers
     DeclException2(ExcAccessToNonPresentElement,
                    size_type,
                    size_type,
-                   << "You tried to access element (" << arg1 << "/" << arg2
-                   << ")"
-                   << " of a sparse matrix, but it appears to not"
+                   << "You tried to access element (" << arg1 << '/' << arg2
+                   << ')' << " of a sparse matrix, but it appears to not"
                    << " exist in the Trilinos sparsity pattern.");
     //@}
   private:
diff --git a/include/deal.II/lac/trilinos_vector.h b/include/deal.II/lac/trilinos_vector.h
index b65e50c1e6..2b07272748 100644
--- a/include/deal.II/lac/trilinos_vector.h
+++ b/include/deal.II/lac/trilinos_vector.h
@@ -1287,7 +1287,7 @@ namespace TrilinosWrappers
         << " of a distributed vector, but this element is not stored "
         << "on the current processor. Note: There are " << arg2
         << " elements stored "
-        << "on the current processor from within the range [" << arg3 << ","
+        << "on the current processor from within the range [" << arg3 << ','
         << arg4 << "] but Trilinos vectors need not store contiguous "
         << "ranges on each processor, and not every element in "
         << "this range may in fact be stored locally."
diff --git a/include/deal.II/matrix_free/dof_info.templates.h b/include/deal.II/matrix_free/dof_info.templates.h
index 814988d4d7..63ff5f22a3 100644
--- a/include/deal.II/matrix_free/dof_info.templates.h
+++ b/include/deal.II/matrix_free/dof_info.templates.h
@@ -708,7 +708,7 @@ namespace internal
               for (unsigned int j = 0; j < con_it->first; ++j, ++index)
                 {
                   Assert(glob_indices + index != end_row, ExcInternalError());
-                  out << glob_indices[index] << " ";
+                  out << glob_indices[index] << ' ';
                 }
 
               out << "[ ";
@@ -717,14 +717,14 @@ namespace internal
                    k++, index++)
                 {
                   Assert(glob_indices + index != end_row, ExcInternalError());
-                  out << glob_indices[index] << "/" << constraint_pool_data[k]
-                      << " ";
+                  out << glob_indices[index] << '/' << constraint_pool_data[k]
+                      << ' ';
                 }
               out << "] ";
             }
           glob_indices += index;
           for (; glob_indices != end_row; ++glob_indices)
-            out << *glob_indices << " ";
+            out << *glob_indices << ' ';
           out << std::endl;
         }
     }
diff --git a/include/deal.II/meshworker/local_results.h b/include/deal.II/meshworker/local_results.h
index c9587fdfe3..61a0135170 100644
--- a/include/deal.II/meshworker/local_results.h
+++ b/include/deal.II/meshworker/local_results.h
@@ -675,10 +675,10 @@ namespace MeshWorker
     os << "M: " << M1.size() << " face " << M2.size() << std::endl;
     for (unsigned int i = 0; i < M1.size(); ++i)
       {
-        os << "  " << M1[i].row << "," << M1[i].column << " "
+        os << "  " << M1[i].row << ',' << M1[i].column << ' '
            << M1[i].matrix.m() << 'x' << M1[i].matrix.n();
         if (i < M2.size())
-          os << " face " << M2[i].row << "," << M2[i].column << " "
+          os << " face " << M2[i].row << ',' << M2[i].column << ' '
              << M2[i].matrix.m() << 'x' << M2[i].matrix.n();
         os << std::endl;
       }
diff --git a/include/deal.II/multigrid/mg_transfer.templates.h b/include/deal.II/multigrid/mg_transfer.templates.h
index 2b8c186bf4..2ca27ee055 100644
--- a/include/deal.II/multigrid/mg_transfer.templates.h
+++ b/include/deal.II/multigrid/mg_transfer.templates.h
@@ -260,7 +260,7 @@ MGLevelGlobalTransfer<VectorType>::copy_to_mg(
 #ifdef DEBUG_OUTPUT
       ierr = MPI_Barrier(MPI_COMM_WORLD);
       AssertThrowMPI(ierr);
-      std::cout << "copy_to_mg dst " << level << " " << dst_level.l2_norm()
+      std::cout << "copy_to_mg dst " << level << ' ' << dst_level.l2_norm()
                 << std::endl;
 #endif
     }
@@ -298,7 +298,7 @@ MGLevelGlobalTransfer<VectorType>::copy_from_mg(
 #ifdef DEBUG_OUTPUT
       int ierr = MPI_Barrier(MPI_COMM_WORLD);
       AssertThrowMPI(ierr);
-      std::cout << "copy_from_mg src " << level << " " << src[level].l2_norm()
+      std::cout << "copy_from_mg src " << level << ' ' << src[level].l2_norm()
                 << std::endl;
       ierr = MPI_Barrier(MPI_COMM_WORLD);
       AssertThrowMPI(ierr);
@@ -323,7 +323,7 @@ MGLevelGlobalTransfer<VectorType>::copy_from_mg(
         dst.compress(VectorOperation::insert);
         ierr = MPI_Barrier(MPI_COMM_WORLD);
         AssertThrowMPI(ierr);
-        std::cout << "copy_from_mg level=" << level << " " << dst.l2_norm()
+        std::cout << "copy_from_mg level=" << level << ' ' << dst.l2_norm()
                   << std::endl;
       }
 #endif
diff --git a/include/deal.II/optimization/line_minimization.h b/include/deal.II/optimization/line_minimization.h
index 408697fa45..5ae4cf4f36 100644
--- a/include/deal.II/optimization/line_minimization.h
+++ b/include/deal.II/optimization/line_minimization.h
@@ -595,8 +595,8 @@ namespace LineMinimization
 
           if (debug_output)
             deallog << "Bracketing phase: " << i << std::endl
-                    << ai << " " << fi << " " << gi << " " << w1(ai, fi) << " "
-                    << w2(gi) << " " << f_min << std::endl;
+                    << ai << ' ' << fi << ' ' << gi << ' ' << w1(ai, fi) << ' '
+                    << w2(gi) << ' ' << f_min << std::endl;
 
           // first check if we can stop bracketing or the whole line search:
           if (fi <= f_min || ai == a_max)
@@ -703,11 +703,11 @@ namespace LineMinimization
 
         if (debug_output)
           deallog << "Sectioning phase: " << i << std::endl
-                  << a_lo << " " << f_lo << " " << g_lo << " " << w1(a_lo, f_lo)
-                  << " " << w2(g_lo) << std::endl
-                  << a_hi << " " << f_hi << " " << g_hi << " " << w1(a_hi, f_hi)
-                  << " " << w2(g_hi) << std::endl
-                  << ai << " " << fi << " " << gi << " " << w1(ai, fi) << " "
+                  << a_lo << ' ' << f_lo << ' ' << g_lo << ' ' << w1(a_lo, f_lo)
+                  << ' ' << w2(g_lo) << std::endl
+                  << a_hi << ' ' << f_hi << ' ' << g_hi << ' ' << w1(a_hi, f_hi)
+                  << ' ' << w2(g_hi) << std::endl
+                  << ai << ' ' << fi << ' ' << gi << ' ' << w1(ai, fi) << ' '
                   << w2(gi) << std::endl;
 
         if (!w1(ai, fi) || fi >= f_lo)
diff --git a/include/deal.II/physics/notation.h b/include/deal.II/physics/notation.h
index 0410b0ad8e..1163e202db 100644
--- a/include/deal.II/physics/notation.h
+++ b/include/deal.II/physics/notation.h
@@ -305,7 +305,7 @@ namespace Physics
                      int,
                      int,
                      << "The number of rows in the input matrix is " << arg1
-                     << ", but needs to be either " << arg2 << "," << arg3
+                     << ", but needs to be either " << arg2 << ',' << arg3
                      << ", or " << arg4 << '.');
 
 
@@ -330,7 +330,7 @@ namespace Physics
                      int,
                      int,
                      << "The number of columns in the input matrix is " << arg1
-                     << ", but needs to be either " << arg2 << "," << arg3
+                     << ", but needs to be either " << arg2 << ',' << arg3
                      << ", or " << arg4 << '.');
 
 
diff --git a/tests/adolc/step-44.cc b/tests/adolc/step-44.cc
index 5f2f2e9cc3..3790385964 100644
--- a/tests/adolc/step-44.cc
+++ b/tests/adolc/step-44.cc
@@ -1242,7 +1242,7 @@ namespace Step44
   {
     std::cout << std::endl
               << "Timestep " << time.get_timestep() << " @ " << time.current()
-              << "s" << std::endl;
+              << 's' << std::endl;
     BlockVector<double> newton_update(dofs_per_block);
     error_residual.reset();
     error_residual_0.reset();
@@ -1254,7 +1254,7 @@ namespace Step44
     unsigned int newton_iteration = 0;
     for (; newton_iteration < parameters.max_iterations_NR; ++newton_iteration)
       {
-        std::cout << " " << std::setw(2) << newton_iteration << " "
+        std::cout << ' ' << std::setw(2) << newton_iteration << ' '
                   << std::flush;
         tangent_matrix = 0.0;
         system_rhs     = 0.0;
@@ -1301,14 +1301,14 @@ namespace Step44
   {
     static const unsigned int l_width = 155;
     for (unsigned int i = 0; i < l_width; ++i)
-      std::cout << "_";
+      std::cout << '_';
     std::cout << std::endl;
     std::cout << "                 SOLVER STEP                  "
               << " |  LIN_IT   LIN_RES    RES_NORM    "
               << " RES_U     RES_P      RES_J     NU_NORM     "
               << " NU_U       NU_P       NU_J " << std::endl;
     for (unsigned int i = 0; i < l_width; ++i)
-      std::cout << "_";
+      std::cout << '_';
     std::cout << std::endl;
   }
   template <int dim>
@@ -1317,7 +1317,7 @@ namespace Step44
   {
     static const unsigned int l_width = 155;
     for (unsigned int i = 0; i < l_width; ++i)
-      std::cout << "_";
+      std::cout << '_';
     std::cout << std::endl;
     const std::pair<double, double> error_dil = get_error_dilation();
     std::cout << "Relative errors:" << std::endl
diff --git a/tests/aniso/fe_tools.cc b/tests/aniso/fe_tools.cc
index 567d26c7ae..15b4ef57c2 100644
--- a/tests/aniso/fe_tools.cc
+++ b/tests/aniso/fe_tools.cc
@@ -44,7 +44,7 @@ print_formatted(const FullMatrix<number> &A,
             deallog << std::setw(width) << std::setprecision(precision)
                     << A(i, j);
           else
-            deallog << std::setw(width) << std::setprecision(precision) << "~";
+            deallog << std::setw(width) << std::setprecision(precision) << '~';
           deallog << ' ';
         };
       deallog << std::endl;
diff --git a/tests/aniso/refine_and_coarsen_anisotropic.cc b/tests/aniso/refine_and_coarsen_anisotropic.cc
index eae698e6fc..5061f3d0ef 100644
--- a/tests/aniso/refine_and_coarsen_anisotropic.cc
+++ b/tests/aniso/refine_and_coarsen_anisotropic.cc
@@ -105,7 +105,7 @@ test_isotropic(int type, std::ostream &logfile)
             GridOutFlags::EpsFlagsBase::width, 300, .01, false, 5, false);
           grid_out.set_flags(eps2);
           std::ostringstream filename;
-          filename << "grid_" << type << "_" << cycle << ".eps";
+          filename << "grid_" << type << '_' << cycle << ".eps";
           std::ofstream outfile(filename.str().c_str());
           grid_out.write_eps(tria, outfile);
         }
diff --git a/tests/base/aligned_vector_01.cc b/tests/base/aligned_vector_01.cc
index 5f85221629..068f52acde 100644
--- a/tests/base/aligned_vector_01.cc
+++ b/tests/base/aligned_vector_01.cc
@@ -29,7 +29,7 @@ test()
   VEC a(4);
   deallog << "Constructor: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a[2] = 1;
@@ -42,25 +42,25 @@ test()
 
   deallog << "Insertion: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a.resize(4);
   deallog << "Shrinking: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a.reserve(100);
   deallog << "Reserve: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a = b;
   deallog << "Assignment: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   // check setting elements for large vectors
diff --git a/tests/base/aligned_vector_02.cc b/tests/base/aligned_vector_02.cc
index a489ecc79a..2d82660f30 100644
--- a/tests/base/aligned_vector_02.cc
+++ b/tests/base/aligned_vector_02.cc
@@ -28,10 +28,10 @@ print_vec(VECVEC &v)
 {
   for (unsigned int i = 0; i < v.size(); ++i)
     {
-      deallog << "[";
+      deallog << '[';
       for (unsigned int j = 0; j < v[i].size(); ++j)
-        deallog << v[i][j] << " ";
-      deallog << "]";
+        deallog << v[i][j] << ' ';
+      deallog << ']';
     }
   deallog << std::endl;
 }
diff --git a/tests/base/aligned_vector_03.cc b/tests/base/aligned_vector_03.cc
index 830ac97ff0..f48461e9e5 100644
--- a/tests/base/aligned_vector_03.cc
+++ b/tests/base/aligned_vector_03.cc
@@ -28,7 +28,7 @@ test()
   VEC a(4);
   deallog << "Constructor: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a[2] = true;
@@ -41,25 +41,25 @@ test()
 
   deallog << "Insertion: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a.resize(4);
   deallog << "Shrinking: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a.reserve(100);
   deallog << "Reserve: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a = b;
   deallog << "Assignment: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   // check setting elements for large vectors
diff --git a/tests/base/aligned_vector_05.cc b/tests/base/aligned_vector_05.cc
index 9b9047f4fb..b0864fec3e 100644
--- a/tests/base/aligned_vector_05.cc
+++ b/tests/base/aligned_vector_05.cc
@@ -53,11 +53,11 @@ test()
   AlignedVector<foo> vec;
   vec.push_back(foo(3));
   vec.resize(2, foo(6));
-  deallog << vec[0].element() << " " << vec[1].element() << std::endl;
+  deallog << vec[0].element() << ' ' << vec[1].element() << std::endl;
   vec[1] = foo(13);
-  deallog << vec[0].element() << " " << vec[1].element() << std::endl;
+  deallog << vec[0].element() << ' ' << vec[1].element() << std::endl;
   vec.reserve(3);
-  deallog << vec[0].element() << " " << vec[1].element() << std::endl;
+  deallog << vec[0].element() << ' ' << vec[1].element() << std::endl;
 }
 
 
diff --git a/tests/base/aligned_vector_move.cc b/tests/base/aligned_vector_move.cc
index ec662e4c2e..b0b55cebe3 100644
--- a/tests/base/aligned_vector_move.cc
+++ b/tests/base/aligned_vector_move.cc
@@ -37,7 +37,7 @@ test()
 
   deallog << "Contents of new VEC: ";
   for (unsigned int i = 0; i < b.size(); ++i)
-    deallog << b[i] << " ";
+    deallog << b[i] << ' ';
   deallog << std::endl;
 
   a.resize(6, 42);
@@ -46,7 +46,7 @@ test()
 
   deallog << "Contents of new VEC: ";
   for (unsigned int i = 0; i < a.size(); ++i)
-    deallog << a[i] << " ";
+    deallog << a[i] << ' ';
   deallog << std::endl;
 
   a = std::move(b);
diff --git a/tests/base/anisotropic_2.cc b/tests/base/anisotropic_2.cc
index 605e56de74..a4e278d45a 100644
--- a/tests/base/anisotropic_2.cc
+++ b/tests/base/anisotropic_2.cc
@@ -37,14 +37,14 @@ print_2d(const AnisotropicPolynomials<2> &aniso)
       deallog << std::endl;
       for (unsigned int j = 0; j <= M; ++j)
         {
-          deallog << 1. * i / N << " " << 1. * j / M << " ";
+          deallog << 1. * i / N << ' ' << 1. * j / M << ' ';
           for (unsigned int k = 0; k < aniso.n(); ++k)
             deallog << aniso.compute_value(k, Point<2>(1. * i / N, 1. * j / M))
-                    << " ";
+                    << ' ';
           deallog << std::endl;
           for (unsigned int k = 0; k < aniso.n(); ++k)
             deallog << aniso.compute_grad(k, Point<2>(1. * i / N, 1. * j / M))
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
@@ -88,16 +88,16 @@ print_3d(const AnisotropicPolynomials<3> &aniso)
           deallog << std::endl;
           for (unsigned int k = 0; k <= P; ++k)
             {
-              deallog << 1. * i / N << " " << 1. * j / M << " " << 1. * k / P;
+              deallog << 1. * i / N << ' ' << 1. * j / M << ' ' << 1. * k / P;
               for (unsigned int k = 0; k < aniso.n(); ++k)
                 deallog << aniso.compute_value(
                              k, Point<3>(1. * i / N, 1. * j / M, 1. * k / P))
-                        << " ";
+                        << ' ';
               deallog << std::endl;
               for (unsigned int k = 0; k < aniso.n(); ++k)
                 deallog << aniso.compute_grad(
                              k, Point<3>(1. * i / N, 1. * j / M, 1. * k / P))
-                        << " ";
+                        << ' ';
               deallog << std::endl;
             }
         }
diff --git a/tests/base/bounding_box_1.cc b/tests/base/bounding_box_1.cc
index 8daaf493e7..6d59ef03e3 100644
--- a/tests/base/bounding_box_1.cc
+++ b/tests/base/bounding_box_1.cc
@@ -45,7 +45,7 @@ test_bounding_box()
   deallog << b.get_boundary_points().second << std::endl;
 
   deallog << "Boundary points are inside: " << b.point_inside(boundaries.first)
-          << " " << b.point_inside(boundaries.second) << std::endl;
+          << ' ' << b.point_inside(boundaries.second) << std::endl;
 
   std::vector<Point<spacedim>> test_points;
 
@@ -126,12 +126,12 @@ test_unitary()
   Point<3> p3(0, 0, 1.0);
 
   deallog << "Checking if all vertices are inside: "
-          << b.point_inside(boundaries.first) << " "
+          << b.point_inside(boundaries.first) << ' '
           << b.point_inside(boundaries.second) << std::endl;
 
-  deallog << b.point_inside(p1) << " " << b.point_inside(p2) << " "
-          << b.point_inside(p3) << " " << b.point_inside(p1 + p2) << " "
-          << b.point_inside(p2 + p3) << " " << b.point_inside(p1 + p3) << " "
+  deallog << b.point_inside(p1) << ' ' << b.point_inside(p2) << ' '
+          << b.point_inside(p3) << ' ' << b.point_inside(p1 + p2) << ' '
+          << b.point_inside(p2 + p3) << ' ' << b.point_inside(p1 + p3) << ' '
           << std::endl;
 
   double eps = std::numeric_limits<double>::epsilon();
diff --git a/tests/base/bounding_box_6.cc b/tests/base/bounding_box_6.cc
index 059298b3c8..67e933436b 100644
--- a/tests/base/bounding_box_6.cc
+++ b/tests/base/bounding_box_6.cc
@@ -38,8 +38,8 @@ print_box(const BoundingBox<dim> &box)
   for (unsigned int d = 0; d < dim; ++d)
     {
       if (d > 0)
-        deallog << "x";
-      deallog << "[" << box.lower_bound(d) << ", " << box.upper_bound(d) << "]";
+        deallog << 'x';
+      deallog << '[' << box.lower_bound(d) << ", " << box.upper_bound(d) << ']';
     }
   deallog << std::endl;
 }
@@ -112,7 +112,7 @@ test_side_length()
   const BoundingBox<dim> box(lower_upper_corners);
 
   for (unsigned int d = 0; d < dim; ++d)
-    deallog << box.side_length(d) << " ";
+    deallog << box.side_length(d) << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/base/consensus_algorithm_01.cc b/tests/base/consensus_algorithm_01.cc
index 0cdb1d35e4..af64ddd2b0 100644
--- a/tests/base/consensus_algorithm_01.cc
+++ b/tests/base/consensus_algorithm_01.cc
@@ -57,7 +57,7 @@ test(const MPI_Comm &comm)
       .run();
 
   for (const auto &i : sources)
-    deallog << i << " ";
+    deallog << i << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/base/derivative_forms_04.cc b/tests/base/derivative_forms_04.cc
index 86e8072352..28422e48f0 100644
--- a/tests/base/derivative_forms_04.cc
+++ b/tests/base/derivative_forms_04.cc
@@ -33,7 +33,7 @@ test()
       }
 
   // output the determinants of these objects
-  deallog << "det(dF): " << dF.determinant().real() << " "
+  deallog << "det(dF): " << dF.determinant().real() << ' '
           << dF.determinant().imag() << std::endl;
 }
 
diff --git a/tests/base/function_from_function_objects_01.cc b/tests/base/function_from_function_objects_01.cc
index 5fb967433a..31a14c431b 100644
--- a/tests/base/function_from_function_objects_01.cc
+++ b/tests/base/function_from_function_objects_01.cc
@@ -56,7 +56,7 @@ main()
 
   Vector<double> v(2);
   fun2.vector_value(p, v);
-  deallog << v(0) << " " << v(1) << std::endl;
+  deallog << v(0) << ' ' << v(1) << std::endl;
 
   deallog << fun3.gradient(p) << std::endl;
 
diff --git a/tests/base/function_parser_02.cc b/tests/base/function_parser_02.cc
index 6a8931c1d5..90658ea6fc 100644
--- a/tests/base/function_parser_02.cc
+++ b/tests/base/function_parser_02.cc
@@ -54,12 +54,9 @@ main()
                 function,
                 constants);
 
-  deallog << "Function "
-          << "[" << function[0] << "]"
-          << " @point "
-          << "[" << point << "]"
-          << " is "
-          << "[" << fp.value(point) << "]" << std::endl;
+  deallog << "Function " << '[' << function[0] << ']' << " @point " << '['
+          << point << ']' << " is " << '[' << fp.value(point) << ']'
+          << std::endl;
 
   // now initialize with a function
   // that's a string, not vector of
@@ -69,12 +66,9 @@ main()
                  function[0],
                  constants);
 
-  deallog << "Function "
-          << "[" << function[0] << "]"
-          << " @point "
-          << "[" << point << "]"
-          << " is "
-          << "[" << fp4.value(point) << "]" << std::endl;
+  deallog << "Function " << '[' << function[0] << ']' << " @point " << '['
+          << point << ']' << " is " << '[' << fp4.value(point) << ']'
+          << std::endl;
 
   // now initialize a function without
   // units to check backwards
@@ -84,12 +78,9 @@ main()
   fp2.initialize(FunctionParser<2>::default_variable_names(),
                  function,
                  constants);
-  deallog << "Function "
-          << "[" << function[0] << "]"
-          << " @point "
-          << "[" << point << "]"
-          << " is "
-          << "[" << fp2.value(point) << "]" << std::endl;
+  deallog << "Function " << '[' << function[0] << ']' << " @point " << '['
+          << point << ']' << " is " << '[' << fp2.value(point) << ']'
+          << std::endl;
 
 
 
@@ -100,10 +91,7 @@ main()
                  function[0],
                  constants);
 
-  deallog << "Function "
-          << "[" << function[0] << "]"
-          << " @point "
-          << "[" << point << "]"
-          << " is "
-          << "[" << fp3.value(point) << "]" << std::endl;
+  deallog << "Function " << '[' << function[0] << ']' << " @point " << '['
+          << point << ']' << " is " << '[' << fp3.value(point) << ']'
+          << std::endl;
 }
diff --git a/tests/base/function_parser_05.cc b/tests/base/function_parser_05.cc
index 1a3dcd57ec..6b6d33143e 100644
--- a/tests/base/function_parser_05.cc
+++ b/tests/base/function_parser_05.cc
@@ -84,7 +84,7 @@ test2()
   double c = vector_function.value(point, 1);
 
   // Output the evaluated function
-  deallog << "Function '" << expressions[0] << "," << expressions[1] << "'"
+  deallog << "Function '" << expressions[0] << ',' << expressions[1] << "'"
           << " @ " << point << " is " << std::flush;
   result.print(deallog.get_file_stream(), 4, false);
   deallog.get_file_stream() << "DEAL::" << std::endl;
diff --git a/tests/base/function_parser_08.cc b/tests/base/function_parser_08.cc
index 0f11e5fb5c..110b15c0c9 100644
--- a/tests/base/function_parser_08.cc
+++ b/tests/base/function_parser_08.cc
@@ -85,7 +85,7 @@ test2()
   Assert(c == result[1], ExcInternalError());
 
   // Output the evaluated function
-  deallog << "Function '" << expressions[0] << "," << expressions[1] << "'"
+  deallog << "Function '" << expressions[0] << ',' << expressions[1] << "'"
           << " @ " << point << " is " << result << std::endl;
 }
 
diff --git a/tests/base/functions_04.cc b/tests/base/functions_04.cc
index 87ee67901d..3bd6ed1eaa 100644
--- a/tests/base/functions_04.cc
+++ b/tests/base/functions_04.cc
@@ -145,10 +145,10 @@ check_function(const Functions::FlowFunction<dim> &f,
                         << " )"
                         << " comp "
                         << k
-                        //      << " norms " << d1.norm() << " " << d2.norm()
+                        //      << " norms " << d1.norm() << ' ' << d2.norm()
                         << std::endl;
                 for (unsigned int d = 0; d < dim; ++d)
-                  deallog << " " << gradients[k][i][d] << " "
+                  deallog << ' ' << gradients[k][i][d] << ' '
                           << gradients1[i][k][d] << std::endl;
               }
           }
@@ -164,7 +164,7 @@ check_function(const Functions::FlowFunction<dim> &f,
       for (unsigned int d = 0; d < dim; ++d)
         div += gradients[d][k][d];
       if (std::fabs(div) > 1.e-13)
-        deallog << "Divergence " << k << " " << div << std::endl;
+        deallog << "Divergence " << k << ' ' << div << std::endl;
     }
   deallog << "tested" << std::endl;
 
diff --git a/tests/base/functions_09.cc b/tests/base/functions_09.cc
index b892762016..9969d83c8e 100644
--- a/tests/base/functions_09.cc
+++ b/tests/base/functions_09.cc
@@ -57,7 +57,7 @@ struct PrintTensor
     for (int i = 0; i < dim; ++i)
       {
         PrintTensor<rank - 1, dim>::print_tensor(tensor[i]);
-        deallog << " ";
+        deallog << ' ';
       }
   }
 };
@@ -69,7 +69,7 @@ struct PrintTensor<1, dim>
   print_tensor(const Tensor<1, dim> &tensor)
   {
     for (int i = 0; i < dim; ++i)
-      deallog << tensor[i] << " ";
+      deallog << tensor[i] << ' ';
   }
 };
 
diff --git a/tests/base/functions_12.cc b/tests/base/functions_12.cc
index 3a3c7d3d70..4c64684dbe 100644
--- a/tests/base/functions_12.cc
+++ b/tests/base/functions_12.cc
@@ -48,14 +48,14 @@ check()
     {
       deallog << coeffs[i];
       for (unsigned int d = 0; d < dim; ++d)
-        deallog << " x" << d << "^" << exponents[i][d];
+        deallog << " x" << d << '^' << exponents[i][d];
       if (i < n_mon - 1)
         deallog << " + ";
     }
   deallog << std::endl;
   deallog << "Point: ";
   for (unsigned int d = 0; d < dim; ++d)
-    deallog << p[d] << " ";
+    deallog << p[d] << ' ';
   deallog << std::endl;
 
   deallog << "Value: " << poly.value(p) << std::endl;
diff --git a/tests/base/functions_cspline.cc b/tests/base/functions_cspline.cc
index e0ddef91e3..3a291677e3 100644
--- a/tests/base/functions_cspline.cc
+++ b/tests/base/functions_cspline.cc
@@ -46,7 +46,7 @@ check()
     for (double xi = x[0]; xi <= x.back(); xi += 0.01)
       {
         const double yi = gsl_spline_eval(spline, xi, acc);
-        // deallog << xi << " " << yi << std::endl;
+        // deallog << xi << ' ' << yi << std::endl;
         y_native.push_back(yi);
       }
     gsl_spline_free(spline);
@@ -59,7 +59,7 @@ check()
     for (double xi = x[0]; xi <= x.back(); xi += 0.01)
       {
         const double yi = cspline.value(Point<dim>(xi));
-        // deallog << xi << " " << yi << std::endl;
+        // deallog << xi << ' ' << yi << std::endl;
         y_dealii.push_back(yi);
       }
   }
diff --git a/tests/base/functions_incremental_01.cc b/tests/base/functions_incremental_01.cc
index 36264db4c7..1d1d37eaf8 100644
--- a/tests/base/functions_incremental_01.cc
+++ b/tests/base/functions_incremental_01.cc
@@ -76,12 +76,12 @@ check()
       func.set_time(el.first);
       func.vector_value(point, v1);
       v1.print(deallog.get_file_stream());
-      deallog << "-" << std::endl;
+      deallog << '-' << std::endl;
 
       func.set_time(el.first - el.second);
       func.vector_value(point, v2);
       v2.print(deallog.get_file_stream());
-      deallog << "=" << std::endl;
+      deallog << '=' << std::endl;
 
       inc.set_time(el.first);
       inc.set_decrement(el.second);
diff --git a/tests/base/functions_incremental_02.cc b/tests/base/functions_incremental_02.cc
index 8f274860c2..b808f6c1bd 100644
--- a/tests/base/functions_incremental_02.cc
+++ b/tests/base/functions_incremental_02.cc
@@ -79,12 +79,12 @@ check()
       func.set_time(el.first);
       func.vector_value(point, v1);
       v1.print(deallog.get_file_stream());
-      deallog << "-" << std::endl;
+      deallog << '-' << std::endl;
 
       func.set_time(el.first - el.second);
       func.vector_value(point, v2);
       v2.print(deallog.get_file_stream());
-      deallog << "=" << std::endl;
+      deallog << '=' << std::endl;
 
       inc.set_time(el.first);
       inc.set_decrement(el.second);
diff --git a/tests/base/functions_singularity.cc b/tests/base/functions_singularity.cc
index 3788e86969..b7488390a6 100644
--- a/tests/base/functions_singularity.cc
+++ b/tests/base/functions_singularity.cc
@@ -184,10 +184,10 @@ check_function_derivative(const Functions::FlowFunction<dim> &f,
                         << " )"
                         << " comp "
                         << k
-                        //      << " norms " << d1.norm() << " " << d2.norm()
+                        //      << " norms " << d1.norm() << ' ' << d2.norm()
                         << std::endl;
                 for (unsigned int d = 0; d < dim; ++d)
-                  deallog << " " << gradients[k][i][d] << " "
+                  deallog << ' ' << gradients[k][i][d] << ' '
                           << gradients1[i][k][d] << std::endl;
               }
           }
@@ -203,7 +203,7 @@ check_function_derivative(const Functions::FlowFunction<dim> &f,
       for (unsigned int d = 0; d < dim; ++d)
         div += gradients[d][k][d];
       if (std::fabs(div) > 1.e-13)
-        deallog << "Divergence " << k << " " << div << std::endl;
+        deallog << "Divergence " << k << ' ' << div << std::endl;
     }
   deallog << "tested" << std::endl;
 
diff --git a/tests/base/gauss_lobatto.cc b/tests/base/gauss_lobatto.cc
index c522118337..b0d3c5d9de 100644
--- a/tests/base/gauss_lobatto.cc
+++ b/tests/base/gauss_lobatto.cc
@@ -28,7 +28,7 @@ main()
 
   for (unsigned int n = 2; n < 20; ++n)
     {
-      deallog << "QGaussLobatto(" << n << ")" << std::endl;
+      deallog << "QGaussLobatto(" << n << ')' << std::endl;
 
       QGaussLobatto<1> q(n);
       for (unsigned int i = 0; i < q.size(); ++i)
diff --git a/tests/base/geometric_utilities_01.cc b/tests/base/geometric_utilities_01.cc
index 8c52cc3fa2..d505ce181e 100644
--- a/tests/base/geometric_utilities_01.cc
+++ b/tests/base/geometric_utilities_01.cc
@@ -31,11 +31,11 @@ print(T point1, T point2)
 {
   deallog << std::endl << "Point 1: ";
   for (unsigned int i = 0; i < dim; ++i)
-    deallog << point1[i] << " ";
+    deallog << point1[i] << ' ';
 
   deallog << std::endl << "Point 2: ";
   for (unsigned int i = 0; i < dim; ++i)
-    deallog << point2[i] << " ";
+    deallog << point2[i] << ' ';
 
   deallog << std::endl;
 }
diff --git a/tests/base/geometry_info_2.cc b/tests/base/geometry_info_2.cc
index ef2a4af0ab..7a16bd41cc 100644
--- a/tests/base/geometry_info_2.cc
+++ b/tests/base/geometry_info_2.cc
@@ -51,7 +51,7 @@ test()
   for (const unsigned int f : GeometryInfo<dim>::face_indices())
     deallog << "face normal" << f << ' '
             << (GeometryInfo<dim>::unit_normal_orientation[f] > 0. ? '+' : '-')
-            << "x" << GeometryInfo<dim>::unit_normal_direction[f] << std::endl;
+            << 'x' << GeometryInfo<dim>::unit_normal_direction[f] << std::endl;
 
   for (const unsigned int f : GeometryInfo<dim>::face_indices())
     {
diff --git a/tests/base/geometry_info_3.cc b/tests/base/geometry_info_3.cc
index bf7105ee4c..7bc712ac7c 100644
--- a/tests/base/geometry_info_3.cc
+++ b/tests/base/geometry_info_3.cc
@@ -27,7 +27,7 @@ template <int dim>
 void
 test()
 {
-  deallog << "Checking in " << dim << "d" << std::endl;
+  deallog << "Checking in " << dim << 'd' << std::endl;
 
   for (const unsigned int f : GeometryInfo<dim>::face_indices())
     for (unsigned int v = 0; v < GeometryInfo<dim>::vertices_per_face; ++v)
diff --git a/tests/base/geometry_info_4.cc b/tests/base/geometry_info_4.cc
index d635fedbb2..06382b0091 100644
--- a/tests/base/geometry_info_4.cc
+++ b/tests/base/geometry_info_4.cc
@@ -27,7 +27,7 @@ template <int dim>
 void
 test()
 {
-  deallog << "Checking in " << dim << "d" << std::endl;
+  deallog << "Checking in " << dim << 'd' << std::endl;
 
   // check phi_i(v_j) = delta_{ij}
   for (const unsigned int i : GeometryInfo<dim>::vertex_indices())
diff --git a/tests/base/geometry_info_5.cc b/tests/base/geometry_info_5.cc
index a308d618da..e12b6cbe17 100644
--- a/tests/base/geometry_info_5.cc
+++ b/tests/base/geometry_info_5.cc
@@ -27,7 +27,7 @@ template <int dim>
 void
 test()
 {
-  deallog << "Checking in " << dim << "d" << std::endl;
+  deallog << "Checking in " << dim << 'd' << std::endl;
 
   // check phi_i(v_j) = delta_{ij}
   for (const unsigned int i : GeometryInfo<dim>::vertex_indices())
diff --git a/tests/base/geometry_info_6.cc b/tests/base/geometry_info_6.cc
index 5ecd3bf107..9c97f78a01 100644
--- a/tests/base/geometry_info_6.cc
+++ b/tests/base/geometry_info_6.cc
@@ -27,7 +27,7 @@ template <int dim>
 void
 test()
 {
-  deallog << "Checking in " << dim << "d" << std::endl;
+  deallog << "Checking in " << dim << 'd' << std::endl;
 
   // check the determinant of the
   // transformation for the reference
diff --git a/tests/base/geometry_info_7.cc b/tests/base/geometry_info_7.cc
index e9ab9b7734..84cb534deb 100644
--- a/tests/base/geometry_info_7.cc
+++ b/tests/base/geometry_info_7.cc
@@ -27,7 +27,7 @@ template <int dim>
 void
 test()
 {
-  deallog << "Checking in " << dim << "d" << std::endl;
+  deallog << "Checking in " << dim << 'd' << std::endl;
 
   // check the determinant of the
   // transformation for the reference
diff --git a/tests/base/geometry_info_8.cc b/tests/base/geometry_info_8.cc
index 0739671f85..2029ebe08c 100644
--- a/tests/base/geometry_info_8.cc
+++ b/tests/base/geometry_info_8.cc
@@ -34,14 +34,14 @@ test_vertices()
 
   for (const unsigned int i : GeometryInfo<dim>::face_indices())
     {
-      deallog << "face " << i << ":" << std::endl;
+      deallog << "face " << i << ':' << std::endl;
 
       for (unsigned int o = 0; o < 8; ++o)
         {
           const std::bitset<3> orientation = o;
 
           deallog << "orientation " << orientation[0] << ", flip "
-                  << orientation[1] << ", rotation " << orientation[2] << ":"
+                  << orientation[1] << ", rotation " << orientation[2] << ':'
                   << std::endl
                   << "    ";
 
@@ -67,14 +67,14 @@ test_lines()
 
   for (const unsigned int i : GeometryInfo<dim>::face_indices())
     {
-      deallog << "face " << i << ":" << std::endl;
+      deallog << "face " << i << ':' << std::endl;
 
       for (unsigned int o = 0; o < 8; ++o)
         {
           const std::bitset<3> orientation = o;
 
           deallog << "orientation " << orientation[0] << ", flip "
-                  << orientation[1] << ", rotation " << orientation[2] << ":"
+                  << orientation[1] << ", rotation " << orientation[2] << ':'
                   << std::endl
                   << "    ";
 
diff --git a/tests/base/graph_coloring_01.cc b/tests/base/graph_coloring_01.cc
index 3f19211f3a..7dbc8ee5c0 100644
--- a/tests/base/graph_coloring_01.cc
+++ b/tests/base/graph_coloring_01.cc
@@ -76,7 +76,7 @@ check()
       deallog << "Color: " << color << std::endl;
       for (unsigned int i = 0; i < coloring[color].size(); ++i)
         for (unsigned int j = 0; j < dim; ++j)
-          deallog << coloring[color][i]->center()[j] << " ";
+          deallog << coloring[color][i]->center()[j] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/base/graph_coloring_02.cc b/tests/base/graph_coloring_02.cc
index febdbd044c..c6095c7527 100644
--- a/tests/base/graph_coloring_02.cc
+++ b/tests/base/graph_coloring_02.cc
@@ -85,7 +85,7 @@ check()
       deallog << "Color: " << color << std::endl;
       for (unsigned int i = 0; i < coloring[color].size(); ++i)
         for (unsigned int j = 0; j < dim; ++j)
-          deallog << coloring[color][i]->center()[j] << " ";
+          deallog << coloring[color][i]->center()[j] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/base/graph_coloring_03.cc b/tests/base/graph_coloring_03.cc
index bce5e83ed1..a499b16b6b 100644
--- a/tests/base/graph_coloring_03.cc
+++ b/tests/base/graph_coloring_03.cc
@@ -88,7 +88,7 @@ check()
       deallog << "Color: " << color << std::endl;
       for (unsigned int i = 0; i < coloring[color].size(); ++i)
         for (unsigned int j = 0; j < dim; ++j)
-          deallog << coloring[color][i]->center()[j] << " ";
+          deallog << coloring[color][i]->center()[j] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/base/hdf5_03.cc b/tests/base/hdf5_03.cc
index 6bebeb512d..816b06c814 100644
--- a/tests/base/hdf5_03.cc
+++ b/tests/base/hdf5_03.cc
@@ -197,7 +197,7 @@ write_test(HDF5::Group &              root_group,
       type_name = std::string("unsigned int");
     }
 
-  deallog << "Write tests for " << container_name << "<" << type_name << ">"
+  deallog << "Write tests for " << container_name << '<' << type_name << '>'
           << " datasets" << std::endl;
 
   auto group = root_group.create_group(container_name + "<" + type_name + ">");
@@ -207,15 +207,15 @@ write_test(HDF5::Group &              root_group,
     auto        dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_rank()
+            << std::endl;
     auto data = initialize_container<Container, Number>(dataset_dimensions);
     assign_data(data);
     if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
@@ -226,18 +226,18 @@ write_test(HDF5::Group &              root_group,
       {
         dataset.template write_none<Number>();
       }
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << container_sum(data) << std::endl;
-    pcout << "IO mode " + dataset_name << " " << container_name << "<"
-          << type_name << ">"
-          << " (Write): " << dataset.get_io_mode() << std::endl;
-    pcout << "Local no collective cause " + dataset_name << " "
-          << container_name << "<" << type_name << ">"
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << container_sum(data)
+            << std::endl;
+    pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+          << type_name << '>' << " (Write): " << dataset.get_io_mode()
+          << std::endl;
+    pcout << "Local no collective cause " + dataset_name << ' '
+          << container_name << '<' << type_name << '>'
           << " (Write): " << dataset.get_local_no_collective_cause()
           << std::endl;
-    pcout << "Global no collective cause " + dataset_name << " "
-          << container_name << "<" << type_name << ">"
+    pcout << "Global no collective cause " + dataset_name << ' '
+          << container_name << '<' << type_name << '>'
           << " (Write): " << dataset.get_global_no_collective_cause()
           << std::endl;
   }
@@ -247,15 +247,15 @@ write_test(HDF5::Group &              root_group,
     auto        dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_rank()
+            << std::endl;
 
     std::vector<hsize_t> coordinates_a = {0,
                                           0, // first point
@@ -305,21 +305,20 @@ write_test(HDF5::Group &              root_group,
       {
         dataset.template write_none<Number>();
       }
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): "
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): "
             << container_sum(data_a) + container_sum(data_b) +
                  container_sum(data_c)
             << std::endl;
-    pcout << "IO mode " + dataset_name << " " << container_name << "<"
-          << type_name << ">"
-          << " (Write): " << dataset.get_io_mode() << std::endl;
-    pcout << "Local no collective cause " + dataset_name << " "
-          << container_name << "<" << type_name << ">"
+    pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+          << type_name << '>' << " (Write): " << dataset.get_io_mode()
+          << std::endl;
+    pcout << "Local no collective cause " + dataset_name << ' '
+          << container_name << '<' << type_name << '>'
           << " (Write): " << dataset.get_local_no_collective_cause()
           << std::endl;
-    pcout << "Global no collective cause " + dataset_name << " "
-          << container_name << "<" << type_name << ">"
+    pcout << "Global no collective cause " + dataset_name << ' '
+          << container_name << '<' << type_name << '>'
           << " (Write): " << dataset.get_global_no_collective_cause()
           << std::endl;
   }
@@ -333,15 +332,15 @@ write_test(HDF5::Group &              root_group,
         auto        dataset =
           group.create_dataset<Number>(dataset_name, dataset_dimensions);
         dataset.set_query_io_mode(true);
-        deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << dataset.get_dimensions() << std::endl;
-        deallog << "Size " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << dataset.get_size() << std::endl;
-        deallog << "Rank " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << dataset.get_rank() << std::endl;
+        deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << dataset.get_dimensions()
+                << std::endl;
+        deallog << "Size " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << dataset.get_size()
+                << std::endl;
+        deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << dataset.get_rank()
+                << std::endl;
         auto data = initialize_container<Container, double>(dataset_dimensions);
         assign_data(data);
         if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
@@ -352,9 +351,9 @@ write_test(HDF5::Group &              root_group,
           {
             dataset.template write_none<Number>();
           }
-        deallog << "Sum " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << container_sum(data) << std::endl;
+        deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << container_sum(data)
+                << std::endl;
       }
     else if (std::is_same<Number, double>::value)
       {
@@ -372,18 +371,18 @@ write_test(HDF5::Group &              root_group,
           {
             dataset.template write_none<Number>();
           }
-        deallog << "Sum " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << container_sum(data) << std::endl;
-        pcout << "IO mode " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+        deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << container_sum(data)
+                << std::endl;
+        pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Write): " << dataset.get_io_mode()
+              << std::endl;
+        pcout << "Local no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -394,15 +393,15 @@ write_test(HDF5::Group &              root_group,
     auto        dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_rank()
+            << std::endl;
     const std::vector<hsize_t> hyperslab_dimensions_a = {2, 5};
     const std::vector<hsize_t> hyperslab_offset_a     = {0, 0};
     auto                       hyperslab_data_a =
@@ -454,28 +453,27 @@ write_test(HDF5::Group &              root_group,
         dataset.template write_none<Number>();
       }
 
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): "
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): "
             << container_sum(hyperslab_data_a) +
                  container_sum(hyperslab_data_b) +
                  container_sum(hyperslab_data_c)
             << std::endl;
-    deallog << "Hyperslab_a sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
+    deallog << "Hyperslab_a sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>'
             << " (Write): " << container_sum(hyperslab_data_a) << std::endl;
-    deallog << "Hyperslab_b sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
+    deallog << "Hyperslab_b sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>'
             << " (Write): " << container_sum(hyperslab_data_b) << std::endl;
-    pcout << "IO mode " + dataset_name << " " << container_name << "<"
-          << type_name << ">"
-          << " (Write): " << dataset.get_io_mode() << std::endl;
-    pcout << "Local no collective cause " + dataset_name << " "
-          << container_name << "<" << type_name << ">"
+    pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+          << type_name << '>' << " (Write): " << dataset.get_io_mode()
+          << std::endl;
+    pcout << "Local no collective cause " + dataset_name << ' '
+          << container_name << '<' << type_name << '>'
           << " (Write): " << dataset.get_local_no_collective_cause()
           << std::endl;
-    pcout << "Global no collective cause " + dataset_name << " "
-          << container_name << "<" << type_name << ">"
+    pcout << "Global no collective cause " + dataset_name << ' '
+          << container_name << '<' << type_name << '>'
           << " (Write): " << dataset.get_global_no_collective_cause()
           << std::endl;
   }
@@ -527,7 +525,7 @@ read_test(HDF5::Group        root_group,
       type_name = std::string("unsigned int");
     }
 
-  deallog << "Read tests for " << container_name << "<" << type_name << ">"
+  deallog << "Read tests for " << container_name << '<' << type_name << '>'
           << " datasets" << std::endl;
 
   auto group = root_group.open_group(container_name + "<" + type_name + ">");
@@ -536,28 +534,28 @@ read_test(HDF5::Group        root_group,
     std::string dataset_name("dataset_1");
     auto        dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_rank()
+            << std::endl;
     Container<Number> data = dataset.read<Container<Number>>();
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << container_sum(data) << std::endl;
-    pcout << "IO mode " + dataset_name << " " << container_name << "<"
-          << type_name << ">"
-          << " (Read): " << dataset.get_io_mode() << std::endl;
-    pcout << "Local no collective cause " + dataset_name << " "
-          << container_name << "<" << type_name << ">"
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << container_sum(data)
+            << std::endl;
+    pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+          << type_name << '>' << " (Read): " << dataset.get_io_mode()
+          << std::endl;
+    pcout << "Local no collective cause " + dataset_name << ' '
+          << container_name << '<' << type_name << '>'
           << " (Read): " << dataset.get_local_no_collective_cause()
           << std::endl;
-    pcout << "Global no collective cause " + dataset_name << " "
-          << container_name << "<" << type_name << ">"
+    pcout << "Global no collective cause " + dataset_name << ' '
+          << container_name << '<' << type_name << '>'
           << " (Read): " << dataset.get_global_no_collective_cause()
           << std::endl;
   }
@@ -566,29 +564,29 @@ read_test(HDF5::Group        root_group,
     std::string dataset_name("dataset_2");
     auto        dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_rank()
+            << std::endl;
     {
       Container<Number> data = dataset.read<Container<Number>>();
-      deallog << "Sum " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << container_sum(data) << std::endl;
-      pcout << "IO mode " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << container_sum(data)
+              << std::endl;
+      pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_io_mode()
+            << std::endl;
+      pcout << "Local no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      pcout << "Global no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
     }
@@ -604,19 +602,19 @@ read_test(HDF5::Group        root_group,
                                             12}; // fourth point
       auto                 data_a =
         dataset.template read_selection<std::vector<Number>>(coordinates_a);
-      deallog << "Selection " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << data_a[0] << ", " << data_a[1] << ", "
-              << data_a[2] << ", " << data_a[3] << std::endl;
-      pcout << "IO mode " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      deallog << "Selection " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << data_a[0] << ", "
+              << data_a[1] << ", " << data_a[2] << ", " << data_a[3]
+              << std::endl;
+      pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_io_mode()
+            << std::endl;
+      pcout << "Local no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      pcout << "Global no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
     }
@@ -631,28 +629,28 @@ read_test(HDF5::Group        root_group,
         std::string dataset_name("dataset_3");
         auto        dataset = group.open_dataset(dataset_name);
         dataset.set_query_io_mode(true);
-        deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_dimensions() << std::endl;
-        deallog << "Size " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_size() << std::endl;
-        deallog << "Rank " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_rank() << std::endl;
+        deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_dimensions()
+                << std::endl;
+        deallog << "Size " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_size()
+                << std::endl;
+        deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_rank()
+                << std::endl;
         Container<Number> data = dataset.read<Container<Number>>();
-        deallog << "Sum " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << container_sum(data) << std::endl;
-        pcout << "IO mode " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+        deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << container_sum(data)
+                << std::endl;
+        pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << dataset.get_io_mode()
+              << std::endl;
+        pcout << "Local no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Read): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Read): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -662,29 +660,29 @@ read_test(HDF5::Group        root_group,
     std::string dataset_name("dataset_4");
     auto        dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_rank()
+            << std::endl;
     {
       Container<Number> data = dataset.read<Container<Number>>();
-      deallog << "Sum " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << container_sum(data) << std::endl;
-      pcout << "IO mode " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << container_sum(data)
+              << std::endl;
+      pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_io_mode()
+            << std::endl;
+      pcout << "Local no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      pcout << "Global no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
     }
@@ -695,18 +693,18 @@ read_test(HDF5::Group        root_group,
       auto                       data_a =
         dataset.read_hyperslab<Container<Number>>(hyperslab_offset_a,
                                                   hyperslab_count_a);
-      deallog << "Hyperslab_a sum " + dataset_name << " " << container_name
-              << "<" << type_name << ">"
-              << " (Read): " << container_sum(data_a) << std::endl;
-      pcout << "IO mode " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      deallog << "Hyperslab_a sum " + dataset_name << ' ' << container_name
+              << '<' << type_name << '>' << " (Read): " << container_sum(data_a)
+              << std::endl;
+      pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_io_mode()
+            << std::endl;
+      pcout << "Local no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      pcout << "Global no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
     }
@@ -732,18 +730,18 @@ read_test(HDF5::Group        root_group,
               dataset.read_none<Number>();
             }
         }
-      deallog << "Hyperslab_b sum " + dataset_name << " " << container_name
-              << "<" << type_name << ">"
-              << " (Read): " << container_sum(data_b) << std::endl;
-      pcout << "IO mode " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      deallog << "Hyperslab_b sum " + dataset_name << ' ' << container_name
+              << '<' << type_name << '>' << " (Read): " << container_sum(data_b)
+              << std::endl;
+      pcout << "IO mode " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_io_mode()
+            << std::endl;
+      pcout << "Local no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " + dataset_name << " "
-            << container_name << "<" << type_name << ">"
+      pcout << "Global no collective cause " + dataset_name << ' '
+            << container_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
     }
diff --git a/tests/base/hdf5_04.cc b/tests/base/hdf5_04.cc
index 1807ccc428..2389ed8662 100644
--- a/tests/base/hdf5_04.cc
+++ b/tests/base/hdf5_04.cc
@@ -194,7 +194,7 @@ write_test(HDF5::Group &              root_group,
       type_name = std::string("unsigned int");
     }
 
-  deallog << "Write tests for " << container_name << "<" << type_name << ">"
+  deallog << "Write tests for " << container_name << '<' << type_name << '>'
           << " datasets" << std::endl;
 
   auto group = root_group.create_group(container_name + "<" + type_name + ">");
@@ -204,30 +204,30 @@ write_test(HDF5::Group &              root_group,
     auto        dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_rank()
+            << std::endl;
     auto data = initialize_container<Container, Number>(dataset_dimensions);
     assign_data(data);
     dataset.write(data);
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << container_sum(data) << std::endl;
-    std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Write): " << dataset.get_io_mode() << std::endl;
-    std::cout << "Local no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << container_sum(data)
+            << std::endl;
+    std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Write): " << dataset.get_io_mode()
+              << std::endl;
+    std::cout << "Local no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-    std::cout << "Global no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    std::cout << "Global no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
   }
@@ -237,15 +237,15 @@ write_test(HDF5::Group &              root_group,
     auto        dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_rank()
+            << std::endl;
 
     std::vector<hsize_t> coordinates_a = {0,
                                           0, // first point
@@ -282,21 +282,20 @@ write_test(HDF5::Group &              root_group,
     dataset.write_selection(data_a, coordinates_a);
     dataset.write_selection(data_b, coordinates_b);
     dataset.write_selection(data_c, coordinates_c);
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): "
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): "
             << container_sum(data_a) + container_sum(data_b) +
                  container_sum(data_c)
             << std::endl;
-    std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Write): " << dataset.get_io_mode() << std::endl;
-    std::cout << "Local no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Write): " << dataset.get_io_mode()
+              << std::endl;
+    std::cout << "Local no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-    std::cout << "Global no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    std::cout << "Global no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
   }
@@ -310,21 +309,21 @@ write_test(HDF5::Group &              root_group,
         auto        dataset =
           group.create_dataset<Number>(dataset_name, dataset_dimensions);
         dataset.set_query_io_mode(true);
-        deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << dataset.get_dimensions() << std::endl;
-        deallog << "Size " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << dataset.get_size() << std::endl;
-        deallog << "Rank " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << dataset.get_rank() << std::endl;
+        deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << dataset.get_dimensions()
+                << std::endl;
+        deallog << "Size " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << dataset.get_size()
+                << std::endl;
+        deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << dataset.get_rank()
+                << std::endl;
         auto data = initialize_container<Container, double>(dataset_dimensions);
         assign_data(data);
         dataset.write(data);
-        deallog << "Sum " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << container_sum(data) << std::endl;
+        deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << container_sum(data)
+                << std::endl;
       }
     else if (std::is_same<Number, double>::value)
       {
@@ -335,18 +334,18 @@ write_test(HDF5::Group &              root_group,
         auto data = initialize_container<Container, float>(dataset_dimensions);
         assign_data(data);
         dataset.write(data);
-        deallog << "Sum " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Write): " << container_sum(data) << std::endl;
-        std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-                  << type_name << ">"
-                  << " (Write): " << dataset.get_io_mode() << std::endl;
-        std::cout << "Local no collective cause " + dataset_name << " "
-                  << container_name << "<" << type_name << ">"
+        deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Write): " << container_sum(data)
+                << std::endl;
+        std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+                  << type_name << '>' << " (Write): " << dataset.get_io_mode()
+                  << std::endl;
+        std::cout << "Local no collective cause " + dataset_name << ' '
+                  << container_name << '<' << type_name << '>'
                   << " (Write): " << dataset.get_local_no_collective_cause()
                   << std::endl;
-        std::cout << "Global no collective cause " + dataset_name << " "
-                  << container_name << "<" << type_name << ">"
+        std::cout << "Global no collective cause " + dataset_name << ' '
+                  << container_name << '<' << type_name << '>'
                   << " (Write): " << dataset.get_global_no_collective_cause()
                   << std::endl;
       }
@@ -357,15 +356,15 @@ write_test(HDF5::Group &              root_group,
     auto        dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << dataset.get_rank()
+            << std::endl;
     const std::vector<hsize_t> hyperslab_dimensions_a = {2, 5};
     const std::vector<hsize_t> hyperslab_offset_a     = {0, 0};
     auto                       hyperslab_data_a =
@@ -400,28 +399,27 @@ write_test(HDF5::Group &              root_group,
                             hyperslab_count_c,
                             hyperslab_block_c);
 
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): "
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): "
             << container_sum(hyperslab_data_a) +
                  container_sum(hyperslab_data_b) +
                  container_sum(hyperslab_data_c)
             << std::endl;
-    deallog << "Hyperslab_a sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
+    deallog << "Hyperslab_a sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>'
             << " (Write): " << container_sum(hyperslab_data_a) << std::endl;
-    deallog << "Hyperslab_b sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
+    deallog << "Hyperslab_b sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>'
             << " (Write): " << container_sum(hyperslab_data_b) << std::endl;
-    std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Write): " << dataset.get_io_mode() << std::endl;
-    std::cout << "Local no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Write): " << dataset.get_io_mode()
+              << std::endl;
+    std::cout << "Local no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-    std::cout << "Global no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    std::cout << "Global no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
   }
@@ -431,9 +429,9 @@ write_test(HDF5::Group &              root_group,
     auto data = initialize_container<Container, Number>(dataset_dimensions);
     assign_data(data);
     group.write_dataset(dataset_name, data);
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Write): " << container_sum(data) << std::endl;
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Write): " << container_sum(data)
+            << std::endl;
   }
 }
 
@@ -481,7 +479,7 @@ read_test(HDF5::Group root_group)
       type_name = std::string("unsigned int");
     }
 
-  deallog << "Read tests for " << container_name << "<" << type_name << ">"
+  deallog << "Read tests for " << container_name << '<' << type_name << '>'
           << " datasets" << std::endl;
 
   auto group = root_group.open_group(container_name + "<" + type_name + ">");
@@ -490,28 +488,28 @@ read_test(HDF5::Group root_group)
     std::string dataset_name("dataset_1");
     auto        dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_rank()
+            << std::endl;
     Container<Number> data = dataset.read<Container<Number>>();
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << container_sum(data) << std::endl;
-    std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << dataset.get_io_mode() << std::endl;
-    std::cout << "Local no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << container_sum(data)
+            << std::endl;
+    std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << dataset.get_io_mode()
+              << std::endl;
+    std::cout << "Local no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Read): " << dataset.get_local_no_collective_cause()
               << std::endl;
-    std::cout << "Global no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    std::cout << "Global no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Read): " << dataset.get_global_no_collective_cause()
               << std::endl;
   }
@@ -520,29 +518,29 @@ read_test(HDF5::Group root_group)
     std::string dataset_name("dataset_2");
     auto        dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_rank()
+            << std::endl;
     {
       Container<Number> data = dataset.read<Container<Number>>();
-      deallog << "Sum " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << container_sum(data) << std::endl;
-      std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << container_sum(data)
+              << std::endl;
+      std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_io_mode()
+                << std::endl;
+      std::cout << "Local no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -558,19 +556,19 @@ read_test(HDF5::Group root_group)
                                             12}; // fourth point
       auto                 data_a =
         dataset.template read_selection<std::vector<Number>>(coordinates_a);
-      deallog << "Selection " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << data_a[0] << ", " << data_a[1] << ", "
-              << data_a[2] << ", " << data_a[3] << std::endl;
-      std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      deallog << "Selection " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << data_a[0] << ", "
+              << data_a[1] << ", " << data_a[2] << ", " << data_a[3]
+              << std::endl;
+      std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_io_mode()
+                << std::endl;
+      std::cout << "Local no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -585,28 +583,28 @@ read_test(HDF5::Group root_group)
         std::string dataset_name("dataset_3");
         auto        dataset = group.open_dataset(dataset_name);
         dataset.set_query_io_mode(true);
-        deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_dimensions() << std::endl;
-        deallog << "Size " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_size() << std::endl;
-        deallog << "Rank " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_rank() << std::endl;
+        deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_dimensions()
+                << std::endl;
+        deallog << "Size " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_size()
+                << std::endl;
+        deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_rank()
+                << std::endl;
         Container<Number> data = dataset.read<Container<Number>>();
-        deallog << "Sum " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << container_sum(data) << std::endl;
-        std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-                  << type_name << ">"
-                  << " (Read): " << dataset.get_io_mode() << std::endl;
-        std::cout << "Local no collective cause " + dataset_name << " "
-                  << container_name << "<" << type_name << ">"
+        deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << container_sum(data)
+                << std::endl;
+        std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+                  << type_name << '>' << " (Read): " << dataset.get_io_mode()
+                  << std::endl;
+        std::cout << "Local no collective cause " + dataset_name << ' '
+                  << container_name << '<' << type_name << '>'
                   << " (Read): " << dataset.get_local_no_collective_cause()
                   << std::endl;
-        std::cout << "Global no collective cause " + dataset_name << " "
-                  << container_name << "<" << type_name << ">"
+        std::cout << "Global no collective cause " + dataset_name << ' '
+                  << container_name << '<' << type_name << '>'
                   << " (Read): " << dataset.get_global_no_collective_cause()
                   << std::endl;
       }
@@ -616,29 +614,29 @@ read_test(HDF5::Group root_group)
     std::string dataset_name("dataset_4");
     auto        dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_rank()
+            << std::endl;
     {
       Container<Number> data = dataset.read<Container<Number>>();
-      deallog << "Sum " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << container_sum(data) << std::endl;
-      std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << container_sum(data)
+              << std::endl;
+      std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_io_mode()
+                << std::endl;
+      std::cout << "Local no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -649,18 +647,18 @@ read_test(HDF5::Group root_group)
       auto                       data_a =
         dataset.read_hyperslab<Container<Number>>(hyperslab_offset_a,
                                                   hyperslab_count_a);
-      deallog << "Hyperslab_a sum " + dataset_name << " " << container_name
-              << "<" << type_name << ">"
-              << " (Read): " << container_sum(data_a) << std::endl;
-      std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      deallog << "Hyperslab_a sum " + dataset_name << ' ' << container_name
+              << '<' << type_name << '>' << " (Read): " << container_sum(data_a)
+              << std::endl;
+      std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_io_mode()
+                << std::endl;
+      std::cout << "Local no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -671,18 +669,18 @@ read_test(HDF5::Group root_group)
       Container<Number>          data_b;
       data_b = dataset.read_hyperslab<Container<Number>>(hyperslab_offset_b,
                                                          hyperslab_count_b);
-      deallog << "Hyperslab_b sum " + dataset_name << " " << container_name
-              << "<" << type_name << ">"
-              << " (Read): " << container_sum(data_b) << std::endl;
-      std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-                << type_name << ">"
-                << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      deallog << "Hyperslab_b sum " + dataset_name << ' ' << container_name
+              << '<' << type_name << '>' << " (Read): " << container_sum(data_b)
+              << std::endl;
+      std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+                << type_name << '>' << " (Read): " << dataset.get_io_mode()
+                << std::endl;
+      std::cout << "Local no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << " "
-                << container_name << "<" << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << ' '
+                << container_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -692,28 +690,28 @@ read_test(HDF5::Group root_group)
     std::string dataset_name("dataset_5");
     auto        dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << dataset.get_rank() << std::endl;
+    deallog << "Dimensions " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_dimensions()
+            << std::endl;
+    deallog << "Size " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_size()
+            << std::endl;
+    deallog << "Rank " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << dataset.get_rank()
+            << std::endl;
     Container<Number> data = dataset.read<Container<Number>>();
-    deallog << "Sum " + dataset_name << " " << container_name << "<"
-            << type_name << ">"
-            << " (Read): " << container_sum(data) << std::endl;
-    std::cout << "IO mode " + dataset_name << " " << container_name << "<"
-              << type_name << ">"
-              << " (Read): " << dataset.get_io_mode() << std::endl;
-    std::cout << "Local no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    deallog << "Sum " + dataset_name << ' ' << container_name << '<'
+            << type_name << '>' << " (Read): " << container_sum(data)
+            << std::endl;
+    std::cout << "IO mode " + dataset_name << ' ' << container_name << '<'
+              << type_name << '>' << " (Read): " << dataset.get_io_mode()
+              << std::endl;
+    std::cout << "Local no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Read): " << dataset.get_local_no_collective_cause()
               << std::endl;
-    std::cout << "Global no collective cause " + dataset_name << " "
-              << container_name << "<" << type_name << ">"
+    std::cout << "Global no collective cause " + dataset_name << ' '
+              << container_name << '<' << type_name << '>'
               << " (Read): " << dataset.get_global_no_collective_cause()
               << std::endl;
   }
diff --git a/tests/base/hdf5_05.cc b/tests/base/hdf5_05.cc
index 94fdb47088..d40de2ccef 100644
--- a/tests/base/hdf5_05.cc
+++ b/tests/base/hdf5_05.cc
@@ -239,11 +239,11 @@ write_test(HDF5::Group &      root_group,
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
     auto data = initialize_container<std::vector, Number>(dataset_dimensions);
     assign_data(data);
@@ -255,17 +255,15 @@ write_test(HDF5::Group &      root_group,
       {
         dataset.template write_none<Number>();
       }
-    deallog << "Data " + dataset_name << "<" << type_name << ">"
+    deallog << "Data " + dataset_name << '<' << type_name << '>'
             << " (Write): " << container_to_string(data) << std::endl;
-    pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+    pcout << "IO mode " + dataset_name << '<' << type_name << '>'
           << " (Write): " << dataset.get_io_mode() << std::endl;
-    pcout << "Local no collective cause " + dataset_name << "<" << type_name
-          << ">"
-          << " (Write): " << dataset.get_local_no_collective_cause()
+    pcout << "Local no collective cause " + dataset_name << '<' << type_name
+          << '>' << " (Write): " << dataset.get_local_no_collective_cause()
           << std::endl;
-    pcout << "Global no collective cause " + dataset_name << "<" << type_name
-          << ">"
-          << " (Write): " << dataset.get_global_no_collective_cause()
+    pcout << "Global no collective cause " + dataset_name << '<' << type_name
+          << '>' << " (Write): " << dataset.get_global_no_collective_cause()
           << std::endl;
   }
 
@@ -284,11 +282,11 @@ write_test(HDF5::Group &      root_group,
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
     auto data = initialize_container<std::vector, Number>(dataset_dimensions);
     assign_data(data);
@@ -300,17 +298,15 @@ write_test(HDF5::Group &      root_group,
       {
         dataset.template write_none<Number>();
       }
-    deallog << "Data " + dataset_name << "<" << type_name << ">"
+    deallog << "Data " + dataset_name << '<' << type_name << '>'
             << " (Write): " << container_to_string(data) << std::endl;
-    pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+    pcout << "IO mode " + dataset_name << '<' << type_name << '>'
           << " (Write): " << dataset.get_io_mode() << std::endl;
-    pcout << "Local no collective cause " + dataset_name << "<" << type_name
-          << ">"
-          << " (Write): " << dataset.get_local_no_collective_cause()
+    pcout << "Local no collective cause " + dataset_name << '<' << type_name
+          << '>' << " (Write): " << dataset.get_local_no_collective_cause()
           << std::endl;
-    pcout << "Global no collective cause " + dataset_name << "<" << type_name
-          << ">"
-          << " (Write): " << dataset.get_global_no_collective_cause()
+    pcout << "Global no collective cause " + dataset_name << '<' << type_name
+          << '>' << " (Write): " << dataset.get_global_no_collective_cause()
           << std::endl;
   }
 
@@ -329,11 +325,11 @@ write_test(HDF5::Group &      root_group,
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
@@ -345,14 +341,13 @@ write_test(HDF5::Group &      root_group,
         const std::vector<hsize_t> hyperslab_count  = {1, 5, 3};
         dataset.write_hyperslab(data, hyperslab_offset, hyperslab_count);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -367,28 +362,26 @@ write_test(HDF5::Group &      root_group,
         const std::vector<hsize_t> hyperslab_count  = {1, 5, 3};
         dataset.write_hyperslab(data, hyperslab_offset, hyperslab_count);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
     else
       {
         dataset.template write_none<Number>();
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -410,11 +403,11 @@ write_test(HDF5::Group &      root_group,
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
@@ -426,14 +419,13 @@ write_test(HDF5::Group &      root_group,
         const std::vector<hsize_t> hyperslab_count  = {3, 1, 4};
         dataset.write_hyperslab(data, hyperslab_offset, hyperslab_count);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -448,28 +440,26 @@ write_test(HDF5::Group &      root_group,
         const std::vector<hsize_t> hyperslab_count  = {3, 1, 4};
         dataset.write_hyperslab(data, hyperslab_offset, hyperslab_count);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
     else
       {
         dataset.template write_none<Number>();
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -492,11 +482,11 @@ write_test(HDF5::Group &      root_group,
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
@@ -517,14 +507,13 @@ write_test(HDF5::Group &      root_group,
 
         dataset.write_selection(data, coordinates);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -546,14 +535,13 @@ write_test(HDF5::Group &      root_group,
 
         dataset.write_selection(data, coordinates);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -578,28 +566,26 @@ write_test(HDF5::Group &      root_group,
 
         dataset.write_selection(data, coordinates);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
     else
       {
         dataset.template write_none<Number>();
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -622,11 +608,11 @@ write_test(HDF5::Group &      root_group,
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
@@ -642,14 +628,13 @@ write_test(HDF5::Group &      root_group,
         dataset.write_hyperslab(
           data, data_dimensions, offset, stride, count, block);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -667,28 +652,26 @@ write_test(HDF5::Group &      root_group,
         dataset.write_hyperslab(
           data, data_dimensions, offset, stride, count, block);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
     else
       {
         dataset.template write_none<Number>();
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -711,11 +694,11 @@ write_test(HDF5::Group &      root_group,
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
@@ -740,14 +723,13 @@ write_test(HDF5::Group &      root_group,
 
         dataset.write_selection(data, coordinates);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -773,14 +755,13 @@ write_test(HDF5::Group &      root_group,
 
         dataset.write_selection(data, coordinates);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -810,28 +791,26 @@ write_test(HDF5::Group &      root_group,
 
         dataset.write_selection(data, coordinates);
 
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
     else
       {
         dataset.template write_none<Number>();
-        pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+        pcout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-        pcout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+        pcout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-        pcout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+        pcout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
       }
@@ -866,27 +845,25 @@ read_test(HDF5::Group        root_group,
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<FullMatrix<Number>>();
 
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -898,18 +875,16 @@ read_test(HDF5::Group        root_group,
                                                               hyperslab_count);
 
       pcout << "Column vector" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Column vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Column vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -921,18 +896,16 @@ read_test(HDF5::Group        root_group,
                                                               hyperslab_count);
 
       pcout << "Row vector" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Row vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Row vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -944,18 +917,16 @@ read_test(HDF5::Group        root_group,
                                                              hyperslab_count);
 
       pcout << "Sub-matrix" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Sub-matrix " + dataset_name << "<" << type_name << ">"
+      deallog << "Sub-matrix " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -973,27 +944,25 @@ read_test(HDF5::Group        root_group,
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -1005,18 +974,16 @@ read_test(HDF5::Group        root_group,
                                                               hyperslab_count);
 
       pcout << "Column vector" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Column vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Column vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -1028,18 +995,16 @@ read_test(HDF5::Group        root_group,
                                                               hyperslab_count);
 
       pcout << "Row vector" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Row vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Row vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -1051,18 +1016,16 @@ read_test(HDF5::Group        root_group,
                                                              hyperslab_count);
 
       pcout << "Sub-matrix" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Sub-matrix " + dataset_name << "<" << type_name << ">"
+      deallog << "Sub-matrix " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -1074,18 +1037,16 @@ read_test(HDF5::Group        root_group,
                                                              hyperslab_count);
 
       pcout << "Sub-matrix" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Sub-matrix " + dataset_name << "<" << type_name << ">"
+      deallog << "Sub-matrix " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -1102,18 +1063,16 @@ read_test(HDF5::Group        root_group,
         data_dimensions, offset, stride, count, block);
 
       pcout << "Sub-matrix" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Sub-matrix " + dataset_name << "<" << type_name << ">"
+      deallog << "Sub-matrix " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -1138,20 +1097,17 @@ read_test(HDF5::Group        root_group,
       auto data = dataset.read_selection<std::vector<Number>>(coordinates);
 
       pcout << "Sub-matrix" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Selection std::vector " + dataset_name << "<" << type_name
-              << ">"
-              << " (Read): " << container_to_string(data) << std::endl;
+      deallog << "Selection std::vector " + dataset_name << '<' << type_name
+              << '>' << " (Read): " << container_to_string(data) << std::endl;
     }
 
     {
@@ -1175,18 +1131,16 @@ read_test(HDF5::Group        root_group,
       auto data = dataset.read_selection<Vector<Number>>(coordinates);
 
       pcout << "Sub-matrix" << std::endl;
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Selection Vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Selection Vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1204,27 +1158,25 @@ read_test(HDF5::Group        root_group,
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1243,27 +1195,25 @@ read_test(HDF5::Group        root_group,
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1283,27 +1233,25 @@ read_test(HDF5::Group        root_group,
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1324,27 +1272,25 @@ read_test(HDF5::Group        root_group,
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<FullMatrix<Number>>();
 
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1364,27 +1310,25 @@ read_test(HDF5::Group        root_group,
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      pcout << "IO mode " + dataset_name << "<" << type_name << ">"
+      pcout << "IO mode " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_io_mode() << std::endl;
-      pcout << "Local no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_local_no_collective_cause()
+      pcout << "Local no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_local_no_collective_cause()
             << std::endl;
-      pcout << "Global no collective cause " << dataset_name << "<" << type_name
-            << ">"
-            << " (Read): " << dataset.get_global_no_collective_cause()
+      pcout << "Global no collective cause " << dataset_name << '<' << type_name
+            << '>' << " (Read): " << dataset.get_global_no_collective_cause()
             << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
diff --git a/tests/base/hdf5_06.cc b/tests/base/hdf5_06.cc
index eb4ddb4028..2034c75d60 100644
--- a/tests/base/hdf5_06.cc
+++ b/tests/base/hdf5_06.cc
@@ -237,27 +237,26 @@ write_test(HDF5::Group &root_group)
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
     auto data = initialize_container<std::vector, Number>(dataset_dimensions);
     assign_data(data);
 
     dataset.write(data);
 
-    deallog << "Data " + dataset_name << "<" << type_name << ">"
+    deallog << "Data " + dataset_name << '<' << type_name << '>'
             << " (Write): " << container_to_string(data) << std::endl;
-    std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+    std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-    std::cout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+    std::cout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-    std::cout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+    std::cout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
   }
@@ -277,27 +276,26 @@ write_test(HDF5::Group &root_group)
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
     auto data = initialize_container<std::vector, Number>(dataset_dimensions);
     assign_data(data);
 
     dataset.write(data);
 
-    deallog << "Data " + dataset_name << "<" << type_name << ">"
+    deallog << "Data " + dataset_name << '<' << type_name << '>'
             << " (Write): " << container_to_string(data) << std::endl;
-    std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+    std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
               << " (Write): " << dataset.get_io_mode() << std::endl;
-    std::cout << "Local no collective cause " + dataset_name << "<" << type_name
-              << ">"
-              << " (Write): " << dataset.get_local_no_collective_cause()
+    std::cout << "Local no collective cause " + dataset_name << '<' << type_name
+              << '>' << " (Write): " << dataset.get_local_no_collective_cause()
               << std::endl;
-    std::cout << "Global no collective cause " + dataset_name << "<"
-              << type_name << ">"
+    std::cout << "Global no collective cause " + dataset_name << '<'
+              << type_name << '>'
               << " (Write): " << dataset.get_global_no_collective_cause()
               << std::endl;
   }
@@ -317,11 +315,11 @@ write_test(HDF5::Group &root_group)
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     {
@@ -332,14 +330,14 @@ write_test(HDF5::Group &root_group)
       const std::vector<hsize_t> hyperslab_count  = {1, 5, 3};
       dataset.write_hyperslab(data, hyperslab_offset, hyperslab_count);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -354,14 +352,14 @@ write_test(HDF5::Group &root_group)
       const std::vector<hsize_t> hyperslab_count  = {1, 5, 3};
       dataset.write_hyperslab(data, hyperslab_offset, hyperslab_count);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -383,11 +381,11 @@ write_test(HDF5::Group &root_group)
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     {
@@ -398,14 +396,14 @@ write_test(HDF5::Group &root_group)
       const std::vector<hsize_t> hyperslab_count  = {3, 1, 4};
       dataset.write_hyperslab(data, hyperslab_offset, hyperslab_count);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -420,14 +418,14 @@ write_test(HDF5::Group &root_group)
       const std::vector<hsize_t> hyperslab_count  = {3, 1, 4};
       dataset.write_hyperslab(data, hyperslab_offset, hyperslab_count);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -450,11 +448,11 @@ write_test(HDF5::Group &root_group)
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     {
@@ -474,14 +472,14 @@ write_test(HDF5::Group &root_group)
 
       dataset.write_selection(data, coordinates);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -503,14 +501,14 @@ write_test(HDF5::Group &root_group)
 
       dataset.write_selection(data, coordinates);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -535,14 +533,14 @@ write_test(HDF5::Group &root_group)
 
       dataset.write_selection(data, coordinates);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -565,11 +563,11 @@ write_test(HDF5::Group &root_group)
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     {
@@ -584,14 +582,14 @@ write_test(HDF5::Group &root_group)
       dataset.write_hyperslab(
         data, data_dimensions, offset, stride, count, block);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -609,14 +607,14 @@ write_test(HDF5::Group &root_group)
       dataset.write_hyperslab(
         data, data_dimensions, offset, stride, count, block);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -639,11 +637,11 @@ write_test(HDF5::Group &root_group)
     auto                       dataset =
       group.create_dataset<Number>(dataset_name, dataset_dimensions);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " << dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " << dataset_name << "<" << type_name << ">"
+    deallog << "Size " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_size() << std::endl;
-    deallog << "Rank " << dataset_name << "<" << type_name << ">"
+    deallog << "Rank " << dataset_name << '<' << type_name << '>'
             << " (Write): " << dataset.get_rank() << std::endl;
 
     {
@@ -667,14 +665,14 @@ write_test(HDF5::Group &root_group)
 
       dataset.write_selection(data, coordinates);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -700,14 +698,14 @@ write_test(HDF5::Group &root_group)
 
       dataset.write_selection(data, coordinates);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -737,14 +735,14 @@ write_test(HDF5::Group &root_group)
 
       dataset.write_selection(data, coordinates);
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Write): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " + dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " + dataset_name << '<'
+                << type_name << '>'
                 << " (Write): " << dataset.get_global_no_collective_cause()
                 << std::endl;
     }
@@ -777,27 +775,27 @@ read_test(HDF5::Group root_group)
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<FullMatrix<Number>>();
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -809,18 +807,18 @@ read_test(HDF5::Group root_group)
                                                               hyperslab_count);
 
       std::cout << "Column vector" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Column vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Column vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -832,18 +830,18 @@ read_test(HDF5::Group root_group)
                                                               hyperslab_count);
 
       std::cout << "Row vector" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Row vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Row vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -855,18 +853,18 @@ read_test(HDF5::Group root_group)
                                                              hyperslab_count);
 
       std::cout << "Sub-matrix" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Sub-matrix " + dataset_name << "<" << type_name << ">"
+      deallog << "Sub-matrix " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -884,27 +882,27 @@ read_test(HDF5::Group root_group)
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -916,18 +914,18 @@ read_test(HDF5::Group root_group)
                                                               hyperslab_count);
 
       std::cout << "Column vector" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Column vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Column vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -939,18 +937,18 @@ read_test(HDF5::Group root_group)
                                                               hyperslab_count);
 
       std::cout << "Row vector" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Row vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Row vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -962,18 +960,18 @@ read_test(HDF5::Group root_group)
                                                              hyperslab_count);
 
       std::cout << "Sub-matrix" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Sub-matrix " + dataset_name << "<" << type_name << ">"
+      deallog << "Sub-matrix " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -985,18 +983,18 @@ read_test(HDF5::Group root_group)
                                                              hyperslab_count);
 
       std::cout << "Sub-matrix" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Sub-matrix " + dataset_name << "<" << type_name << ">"
+      deallog << "Sub-matrix " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -1013,18 +1011,18 @@ read_test(HDF5::Group root_group)
         data_dimensions, offset, stride, count, block);
 
       std::cout << "Sub-matrix" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Sub-matrix " + dataset_name << "<" << type_name << ">"
+      deallog << "Sub-matrix " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
 
@@ -1049,20 +1047,19 @@ read_test(HDF5::Group root_group)
       auto data = dataset.read_selection<std::vector<Number>>(coordinates);
 
       std::cout << "Sub-matrix" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Selection std::vector " + dataset_name << "<" << type_name
-              << ">"
-              << " (Read): " << container_to_string(data) << std::endl;
+      deallog << "Selection std::vector " + dataset_name << '<' << type_name
+              << '>' << " (Read): " << container_to_string(data) << std::endl;
     }
 
     {
@@ -1086,18 +1083,18 @@ read_test(HDF5::Group root_group)
       auto data = dataset.read_selection<Vector<Number>>(coordinates);
 
       std::cout << "Sub-matrix" << std::endl;
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Selection Vector " + dataset_name << "<" << type_name << ">"
+      deallog << "Selection Vector " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1115,27 +1112,27 @@ read_test(HDF5::Group root_group)
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1154,27 +1151,27 @@ read_test(HDF5::Group root_group)
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1194,27 +1191,27 @@ read_test(HDF5::Group root_group)
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1235,27 +1232,27 @@ read_test(HDF5::Group root_group)
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<FullMatrix<Number>>();
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
@@ -1275,27 +1272,27 @@ read_test(HDF5::Group root_group)
 
     auto dataset = group.open_dataset(dataset_name);
     dataset.set_query_io_mode(true);
-    deallog << "Dimensions " + dataset_name << "<" << type_name << ">"
+    deallog << "Dimensions " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_dimensions() << std::endl;
-    deallog << "Size " + dataset_name << "<" << type_name << ">"
+    deallog << "Size " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_size() << std::endl;
-    deallog << "Rank " + dataset_name << "<" << type_name << ">"
+    deallog << "Rank " + dataset_name << '<' << type_name << '>'
             << " (Read): " << dataset.get_rank() << std::endl;
     {
       auto data = dataset.read<std::vector<Number>>();
 
-      std::cout << "IO mode " + dataset_name << "<" << type_name << ">"
+      std::cout << "IO mode " + dataset_name << '<' << type_name << '>'
                 << " (Read): " << dataset.get_io_mode() << std::endl;
-      std::cout << "Local no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Local no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_local_no_collective_cause()
                 << std::endl;
-      std::cout << "Global no collective cause " << dataset_name << "<"
-                << type_name << ">"
+      std::cout << "Global no collective cause " << dataset_name << '<'
+                << type_name << '>'
                 << " (Read): " << dataset.get_global_no_collective_cause()
                 << std::endl;
 
-      deallog << "Data " + dataset_name << "<" << type_name << ">"
+      deallog << "Data " + dataset_name << '<' << type_name << '>'
               << " (Read): " << container_to_string(data) << std::endl;
     }
   }
diff --git a/tests/base/hierarchical.cc b/tests/base/hierarchical.cc
index d6cbaa1ec0..144d839506 100644
--- a/tests/base/hierarchical.cc
+++ b/tests/base/hierarchical.cc
@@ -39,9 +39,9 @@ main()
   for (unsigned int i = 0; i <= div; ++i)
     {
       const double x = 1. * i / div;
-      deallog << x << " ";
+      deallog << x << ' ';
       for (unsigned int j = 0; j < p.size(); ++j)
-        deallog << p[j].value(x) << " ";
+        deallog << p[j].value(x) << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/base/index_set_iterate_01.cc b/tests/base/index_set_iterate_01.cc
index e0cb2473f6..43e66847ba 100644
--- a/tests/base/index_set_iterate_01.cc
+++ b/tests/base/index_set_iterate_01.cc
@@ -37,9 +37,9 @@ test(IndexSet &index_set)
        ++it)
     {
       if (it->n_elements() == 1)
-        deallog << *(it->begin()) << " ";
+        deallog << *(it->begin()) << ' ';
       else
-        deallog << "[" << *(it->begin()) << "," << it->last() << "] ";
+        deallog << '[' << *(it->begin()) << ',' << it->last() << "] ";
     }
   deallog << std::endl;
 
@@ -48,7 +48,7 @@ test(IndexSet &index_set)
     for (IndexSet::ElementIterator it = index_set.begin();
          it != index_set.end();
          ++it)
-      deallog << *it << " ";
+      deallog << *it << ' ';
     deallog << std::endl;
   }
 
diff --git a/tests/base/index_set_readwrite_03.cc b/tests/base/index_set_readwrite_03.cc
index 442839e746..43c868b519 100644
--- a/tests/base/index_set_readwrite_03.cc
+++ b/tests/base/index_set_readwrite_03.cc
@@ -42,7 +42,7 @@ test()
 
   Assert(is1 == is2, ExcInternalError());
 
-  deallog << is1.is_element(4) << " " << is2.is_element(4) << std::endl;
+  deallog << is1.is_element(4) << ' ' << is2.is_element(4) << std::endl;
 
   deallog << "OK" << std::endl;
 
diff --git a/tests/base/mpi_create_partitioning_01.cc b/tests/base/mpi_create_partitioning_01.cc
index b727a4682c..f213252d10 100644
--- a/tests/base/mpi_create_partitioning_01.cc
+++ b/tests/base/mpi_create_partitioning_01.cc
@@ -63,7 +63,7 @@ test()
   deallog << "Total size=" << size << std::endl;
   for (unsigned int p = 0; p < vec.size(); ++p)
     {
-      deallog << "p=" << p << ":" << std::endl;
+      deallog << "p=" << p << ':' << std::endl;
       vec[p].print(deallog.get_file_stream());
     }
 }
diff --git a/tests/base/mpi_evenly_distributed_partitioning_01.cc b/tests/base/mpi_evenly_distributed_partitioning_01.cc
index b64ace6ceb..cc8f8f471f 100644
--- a/tests/base/mpi_evenly_distributed_partitioning_01.cc
+++ b/tests/base/mpi_evenly_distributed_partitioning_01.cc
@@ -80,7 +80,7 @@ test()
   deallog << "Total size=" << size << std::endl;
   for (unsigned int p = 0; p < vec.size(); ++p)
     {
-      deallog << "p=" << p << ":" << std::endl;
+      deallog << "p=" << p << ':' << std::endl;
       vec[p].print(deallog.get_file_stream());
     }
 }
diff --git a/tests/base/mpi_noncontiguous_partitioner_01.cc b/tests/base/mpi_noncontiguous_partitioner_01.cc
index 914944e68b..3ffe496775 100644
--- a/tests/base/mpi_noncontiguous_partitioner_01.cc
+++ b/tests/base/mpi_noncontiguous_partitioner_01.cc
@@ -54,10 +54,10 @@ test(const MPI_Comm comm)
                                  ArrayView<double>(dst.data(), dst.size()));
 
   for (size_t i = 0; i < src.size(); ++i)
-    deallog << static_cast<int>(src[i]) << " ";
+    deallog << static_cast<int>(src[i]) << ' ';
   deallog << std::endl;
   for (size_t i = 0; i < dst.size(); ++i)
-    deallog << static_cast<int>(dst[i]) << " ";
+    deallog << static_cast<int>(dst[i]) << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/base/mpi_noncontiguous_partitioner_02.cc b/tests/base/mpi_noncontiguous_partitioner_02.cc
index 3d82e53e58..a0a0f62a16 100644
--- a/tests/base/mpi_noncontiguous_partitioner_02.cc
+++ b/tests/base/mpi_noncontiguous_partitioner_02.cc
@@ -130,10 +130,10 @@ test(const MPI_Comm &comm, const bool do_revert, const unsigned int dir)
                                  ArrayView<double>(dst.data(), dst.size()));
 
   for (size_t i = 0; i < src.size(); ++i)
-    deallog << static_cast<int>(src[i]) << " ";
+    deallog << static_cast<int>(src[i]) << ' ';
   deallog << std::endl;
   for (size_t i = 0; i < dst.size(); ++i)
-    deallog << static_cast<int>(dst[i]) << " ";
+    deallog << static_cast<int>(dst[i]) << ' ';
   deallog << std::endl << std::endl;
 
 
diff --git a/tests/base/mpi_noncontiguous_partitioner_03.cc b/tests/base/mpi_noncontiguous_partitioner_03.cc
index b456fb2316..e5774f70c9 100644
--- a/tests/base/mpi_noncontiguous_partitioner_03.cc
+++ b/tests/base/mpi_noncontiguous_partitioner_03.cc
@@ -41,10 +41,10 @@ test(const MPI_Comm                       comm,
                                  ArrayView<double>(dst.data(), dst.size()));
 
   for (size_t i = 0; i < src.size(); ++i)
-    deallog << static_cast<int>(src[i]) << " ";
+    deallog << static_cast<int>(src[i]) << ' ';
   deallog << std::endl;
   for (size_t i = 0; i < dst.size(); ++i)
-    deallog << static_cast<int>(dst[i]) << " ";
+    deallog << static_cast<int>(dst[i]) << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/base/mpi_some_to_some_02.cc b/tests/base/mpi_some_to_some_02.cc
index c98c059ae5..cf10223424 100644
--- a/tests/base/mpi_some_to_some_02.cc
+++ b/tests/base/mpi_some_to_some_02.cc
@@ -86,7 +86,7 @@ test(const unsigned int max_particles,
       std::vector<unsigned int> shared_procs(shared_procs_set.begin(),
                                              shared_procs_set.end());
 
-      deallog << "Proc " << my_proc << "/" << n_procs << ": sharing with  "
+      deallog << "Proc " << my_proc << '/' << n_procs << ": sharing with  "
               << Patterns::Tools::to_string(shared_procs_set) << std::endl;
       for (unsigned int i = 0; i < n_local_particles * shared_fraction; ++i)
         shared_particles[shared_procs[random_index(shared_procs.size())]]
diff --git a/tests/base/polynomial1d.cc b/tests/base/polynomial1d.cc
index 3546228802..fa24dfb85e 100644
--- a/tests/base/polynomial1d.cc
+++ b/tests/base/polynomial1d.cc
@@ -169,14 +169,12 @@ main()
 
   for (unsigned int i = 0; i < p.size(); ++i)
     {
-      deallog << "N0(P" << i << ")"
-              << " = " << p[i].value(0.) << std::endl;
+      deallog << "N0(P" << i << ')' << " = " << p[i].value(0.) << std::endl;
     }
 
   for (unsigned int i = 0; i < p.size(); ++i)
     {
-      deallog << "N1(P" << i << ")"
-              << " = " << p[i].value(1.) << std::endl;
+      deallog << "N1(P" << i << ')' << " = " << p[i].value(1.) << std::endl;
     }
 
   std::vector<double> values(p.size());
@@ -190,8 +188,8 @@ main()
       for (unsigned int i = 0; i < p.size(); ++i)
         {
           p[i].value(.5, values);
-          deallog << "N" << j << "(P" << i << ")"
-                  << " = " << values[j] * factor << std::endl;
+          deallog << 'N' << j << "(P" << i << ')' << " = " << values[j] * factor
+                  << std::endl;
         }
     }
 }
diff --git a/tests/base/polynomial_jacobi.cc b/tests/base/polynomial_jacobi.cc
index dee86d583e..27b9d9a934 100644
--- a/tests/base/polynomial_jacobi.cc
+++ b/tests/base/polynomial_jacobi.cc
@@ -32,7 +32,7 @@ main()
     for (int beta = 0; beta < 3; ++beta)
       for (unsigned int degree = 0; degree < 40; ++degree)
         {
-          deallog << "Jacobi_" << degree << "^(" << alpha << "," << beta
+          deallog << "Jacobi_" << degree << "^(" << alpha << ',' << beta
                   << ") at 0.3: "
                   << jacobi_polynomial_value(degree, alpha, beta, 0.3)
                   << std::endl;
@@ -48,7 +48,7 @@ main()
           Assert(roots.size() == 0 || roots.back() < 1., ExcInternalError());
 
           for (unsigned int i = 0; i < roots.size(); ++i)
-            deallog << roots[i] << " ";
+            deallog << roots[i] << ' ';
           deallog << std::endl << std::endl;
         }
 }
diff --git a/tests/base/polynomial_jacobi_roots.cc b/tests/base/polynomial_jacobi_roots.cc
index 7169c9a046..a044177606 100644
--- a/tests/base/polynomial_jacobi_roots.cc
+++ b/tests/base/polynomial_jacobi_roots.cc
@@ -35,7 +35,7 @@ main()
     for (unsigned int degree = 1; degree < 40; degree += 3)
       {
         const int beta = alpha;
-        deallog << "Jacobi_" << degree << "^(" << alpha << "," << beta << ")"
+        deallog << "Jacobi_" << degree << "^(" << alpha << ',' << beta << ')'
                 << std::endl;
 
         std::vector<double> roots =
diff --git a/tests/base/polynomial_jacobi_roots_ld.cc b/tests/base/polynomial_jacobi_roots_ld.cc
index e0045bfded..5b9d109ab0 100644
--- a/tests/base/polynomial_jacobi_roots_ld.cc
+++ b/tests/base/polynomial_jacobi_roots_ld.cc
@@ -35,7 +35,7 @@ main()
     for (unsigned int degree = 1; degree < 40; degree += 3)
       {
         const int beta = alpha;
-        deallog << "Jacobi_" << degree << "^(" << alpha << "," << beta << ")"
+        deallog << "Jacobi_" << degree << "^(" << alpha << ',' << beta << ')'
                 << std::endl;
 
         std::vector<long double> roots =
diff --git a/tests/base/polynomials_adini_01.cc b/tests/base/polynomials_adini_01.cc
index ef7b6cef57..d74b89ce1d 100644
--- a/tests/base/polynomials_adini_01.cc
+++ b/tests/base/polynomials_adini_01.cc
@@ -62,7 +62,7 @@ check_poly_q(const PolynomialsAdini<dim> &poly)
       deallog << "Adini<" << dim << "> point " << i << " (" << points[i][0];
       for (unsigned int d = 1; d < dim; ++d)
         deallog << ", " << points[i][d];
-      deallog << ")" << std::endl;
+      deallog << ')' << std::endl;
 
       poly.evaluate(points[i], values, grads, grads2, thirds, fourths);
 
diff --git a/tests/base/polynomials_br.cc b/tests/base/polynomials_br.cc
index b56697a966..4ff74422ed 100644
--- a/tests/base/polynomials_br.cc
+++ b/tests/base/polynomials_br.cc
@@ -86,7 +86,7 @@ check_poly_q(const PolynomialsBernardiRaugel<dim> &poly)
       deallog << "BR1<" << dim << "> point " << i << " (" << points[i][0];
       for (unsigned int d = 1; d < dim; ++d)
         deallog << ", " << points[i][d];
-      deallog << ")" << std::endl;
+      deallog << ')' << std::endl;
 
       poly.evaluate(points[i], values, grads, grads2, thirds, fourths);
 
@@ -146,7 +146,7 @@ check_poly_bubble(const PolynomialsBernardiRaugel<dim> &poly)
               << points[i][0];
       for (unsigned int d = 1; d < dim; ++d)
         deallog << ", " << points[i][d];
-      deallog << ")" << std::endl;
+      deallog << ')' << std::endl;
 
       poly.evaluate(points[i], values, grads, grads2, thirds, fourths);
 
diff --git a/tests/base/quadrature_check_tensor_product.cc b/tests/base/quadrature_check_tensor_product.cc
index e0d59356a8..5b7b56b841 100644
--- a/tests/base/quadrature_check_tensor_product.cc
+++ b/tests/base/quadrature_check_tensor_product.cc
@@ -49,7 +49,7 @@ check_tensor_product(const std::vector<Quadrature<1>> &quadratures,
           AssertThrow(q_basis[0].size() == q_points.size(), ExcInternalError());
           for (unsigned int q = 0; q < quadrature.size(); ++q)
             {
-              std::cout << q_points[q] << " " << q_basis[0].get_points()[q]
+              std::cout << q_points[q] << ' ' << q_basis[0].get_points()[q]
                         << std::endl;
               AssertThrow(std::abs(
                             (q_points[q] - q_basis[0].get_points()[q]).norm()) <
diff --git a/tests/base/quadrature_move_01.cc b/tests/base/quadrature_move_01.cc
index aea3d5a5c2..f2f5101a8d 100644
--- a/tests/base/quadrature_move_01.cc
+++ b/tests/base/quadrature_move_01.cc
@@ -48,8 +48,8 @@ template <template <int dim> class Quad, typename... Args>
 void
 check_quadrature_move(Args &&...args)
 {
-  deallog << check_q_move<Quad<1>>(std::forward<Args>(args)...) << 1 << " "
-          << check_q_move<Quad<2>>(std::forward<Args>(args)...) << 2 << " "
+  deallog << check_q_move<Quad<1>>(std::forward<Args>(args)...) << 1 << ' '
+          << check_q_move<Quad<2>>(std::forward<Args>(args)...) << 2 << ' '
           << check_q_move<Quad<3>>(std::forward<Args>(args)...) << 3
           << std::endl;
 }
diff --git a/tests/base/quadrature_move_02.cc b/tests/base/quadrature_move_02.cc
index 933a62a679..5842202725 100644
--- a/tests/base/quadrature_move_02.cc
+++ b/tests/base/quadrature_move_02.cc
@@ -55,8 +55,8 @@ void
 check_quadrature_assign_move(Args &&...args)
 {
   deallog << check_q_assign_move<Quad, 1>(std::forward<Args>(args)...) << 1
-          << " " << check_q_assign_move<Quad, 2>(std::forward<Args>(args)...)
-          << 2 << " "
+          << ' ' << check_q_assign_move<Quad, 2>(std::forward<Args>(args)...)
+          << 2 << ' '
           << check_q_assign_move<Quad, 3>(std::forward<Args>(args)...) << 3
           << std::endl;
 }
diff --git a/tests/base/quadrature_qiterated_01.cc b/tests/base/quadrature_qiterated_01.cc
index 6711fe1dfe..544b036113 100644
--- a/tests/base/quadrature_qiterated_01.cc
+++ b/tests/base/quadrature_qiterated_01.cc
@@ -31,8 +31,8 @@ test(const Quadrature<1> &q_outer, const Quadrature<1> &q_inner)
 
   for (unsigned int q = 0; q < quad.size(); ++q)
     {
-      deallog << quad.point(q) << " ";
-      deallog << quad.weight(q) << " ";
+      deallog << quad.point(q) << ' ';
+      deallog << quad.weight(q) << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/base/quadrature_sorted_test.cc b/tests/base/quadrature_sorted_test.cc
index 8286e9b6ac..b943373f5f 100644
--- a/tests/base/quadrature_sorted_test.cc
+++ b/tests/base/quadrature_sorted_test.cc
@@ -92,7 +92,7 @@ check_cells(std::vector<Quadrature<dim> *> &quadratures)
         }
       while (err < 1e-14);
       // Uncomment here for testing
-      //      deallog << " (Int " << quadrature_int << ',' << exact_int << ")";
+      //      deallog << " (Int " << quadrature_int << ',' << exact_int << ')';
       deallog << " is exact for polynomials of degree " << i - 1 << std::endl;
     }
 }
@@ -170,7 +170,7 @@ check_faces(const std::vector<Quadrature<dim - 1> *> &quadratures,
       while (err < (dim == 3 ? 8 : 1) * 2e-14);
       // Uncomment here for testing
       //      deallog << " (Int " << quadrature_int << '-' << exact_int << '='
-      //      << err << ")";
+      //      << err << ')';
       deallog << " is exact for polynomials of degree " << i - 1 << std::endl;
     }
   deallog.pop();
diff --git a/tests/base/quadrature_test.cc b/tests/base/quadrature_test.cc
index 48644e839b..4db0d64fc9 100644
--- a/tests/base/quadrature_test.cc
+++ b/tests/base/quadrature_test.cc
@@ -92,7 +92,7 @@ check_cells(std::vector<Quadrature<dim> *> &quadratures)
         }
       while (err < 1e-14);
       // Uncomment here for testing
-      //      deallog << " (Int " << quadrature_int << ',' << exact_int << ")";
+      //      deallog << " (Int " << quadrature_int << ',' << exact_int << ')';
       deallog << " is exact for polynomials of degree " << i - 1 << std::endl;
 
       if (dim == 1)
@@ -185,7 +185,7 @@ check_faces(const std::vector<Quadrature<dim - 1> *> &quadratures,
       while (err < (dim == 3 ? 8 : 1) * 2e-14);
       // Uncomment here for testing
       //      deallog << " (Int " << quadrature_int << '-' << exact_int << '='
-      //      << err << ")";
+      //      << err << ')';
       deallog << " is exact for polynomials of degree " << i - 1 << std::endl;
     }
   deallog.pop();
diff --git a/tests/base/table.cc b/tests/base/table.cc
index 7f5faafe9b..f7c40a920e 100644
--- a/tests/base/table.cc
+++ b/tests/base/table.cc
@@ -57,7 +57,7 @@ main()
             AssertThrow(&*(Td[i].begin() + j) == &Td(i, j), ExcInternalError());
             AssertThrow(&*(Ti[i].begin() + j) == &Ti(i, j), ExcInternalError());
 
-            deallog << i << " " << j << " " << Td[i][j] << " ok" << std::endl;
+            deallog << i << ' ' << j << ' ' << Td[i][j] << " ok" << std::endl;
           };
     };
 
@@ -87,7 +87,7 @@ main()
             AssertThrow(&*(Td[i].begin() + j) == &Td(i, j), ExcInternalError());
             AssertThrow(&*(Ti[i].begin() + j) == &Ti(i, j), ExcInternalError());
 
-            deallog << i << " " << j << " " << Td[i][j] << " ok" << std::endl;
+            deallog << i << ' ' << j << ' ' << Td[i][j] << " ok" << std::endl;
           };
 
       for (unsigned int i = 0; i < 4; ++i)
@@ -144,7 +144,7 @@ main()
           AssertThrow(Ti[i] == Ti(i), ExcInternalError());
           AssertThrow(Ti[i] == Td(i), ExcInternalError());
 
-          deallog << i << " " << Td[i] << " ok" << std::endl;
+          deallog << i << ' ' << Td[i] << " ok" << std::endl;
         };
     };
 
@@ -184,7 +184,7 @@ main()
               AssertThrow(&*(Ti[i][j].begin() + k) == &Ti(i, j, k),
                           ExcInternalError());
 
-              deallog << i << " " << j << " " << k << " " << Td[i][j][k]
+              deallog << i << ' ' << j << ' ' << k << ' ' << Td[i][j][k]
                       << " ok" << std::endl;
             };
 
@@ -243,7 +243,7 @@ main()
                 AssertThrow(&*(Ti[i][j][k].begin() + l) == &Ti(i, j, k, l),
                             ExcInternalError());
 
-                deallog << i << " " << j << " " << k << " " << l << " "
+                deallog << i << ' ' << j << ' ' << k << ' ' << l << ' '
                         << Td[i][j][k][l] << " ok" << std::endl;
               };
 
@@ -305,8 +305,8 @@ main()
                                 &Ti(i, j, k, l, m),
                               ExcInternalError());
 
-                  deallog << i << " " << j << " " << k << " " << l << " " << m
-                          << " " << Td[i][j][k][l][m] << " ok" << std::endl;
+                  deallog << i << ' ' << j << ' ' << k << ' ' << l << ' ' << m
+                          << ' ' << Td[i][j][k][l][m] << " ok" << std::endl;
                 };
 
       for (unsigned int i = 0; i < I; ++i)
@@ -370,8 +370,8 @@ main()
                                   &Ti(i, j, k, l, m, n),
                                 ExcInternalError());
 
-                    deallog << i << " " << j << " " << k << " " << l << " " << m
-                            << " " << n << " " << Td[i][j][k][l][m][n] << " ok"
+                    deallog << i << ' ' << j << ' ' << k << ' ' << l << ' ' << m
+                            << ' ' << n << ' ' << Td[i][j][k][l][m][n] << " ok"
                             << std::endl;
                   };
 
diff --git a/tests/base/taylor_estimate_function_bounds.cc b/tests/base/taylor_estimate_function_bounds.cc
index a400ddb6ff..ed232d98a0 100644
--- a/tests/base/taylor_estimate_function_bounds.cc
+++ b/tests/base/taylor_estimate_function_bounds.cc
@@ -95,7 +95,7 @@ namespace
   void
   print_bounds(const std::pair<double, double> &bounds)
   {
-    deallog << "[" << bounds.first << ", " << bounds.second << "]" << std::endl;
+    deallog << '[' << bounds.first << ", " << bounds.second << ']' << std::endl;
   }
 
 
@@ -108,7 +108,7 @@ namespace
   void
   run_test()
   {
-    deallog << dim << "D" << std::endl;
+    deallog << dim << 'D' << std::endl;
 
     const TestFunction<dim> function;
     const BoundingBox<dim>  box = create_box<dim>();
diff --git a/tests/base/utilities_02b.cc b/tests/base/utilities_02b.cc
index 3606ec4e31..90e2872230 100644
--- a/tests/base/utilities_02b.cc
+++ b/tests/base/utilities_02b.cc
@@ -31,13 +31,13 @@ do_test(const VectorizedArrayType array)
   auto exponentiated_array = Utilities::fixed_power<3>(array);
 
   for (unsigned int i = 0; i < VectorizedArrayType::size(); ++i)
-    deallog << exponentiated_array[i] << " ";
+    deallog << exponentiated_array[i] << ' ';
   deallog << std::endl;
 
   exponentiated_array = Utilities::fixed_power<-3>(array);
 
   for (unsigned int i = 0; i < VectorizedArrayType::size(); ++i)
-    deallog << exponentiated_array[i] << " ";
+    deallog << exponentiated_array[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/base/utilities_13.cc b/tests/base/utilities_13.cc
index 0ac89bf59e..c68baa6544 100644
--- a/tests/base/utilities_13.cc
+++ b/tests/base/utilities_13.cc
@@ -79,7 +79,7 @@ test1()
   const auto res = Utilities::inverse_Hilbert_space_filling_curve(points, 4);
 
   for (const auto &p : res)
-    deallog << p[0] << " " << p[1] << std::endl;
+    deallog << p[0] << ' ' << p[1] << std::endl;
 }
 
 // https://github.com/aditi137/Hilbert/blob/master/Hilbert/test.py
@@ -93,7 +93,7 @@ test2()
   const auto res = Utilities::inverse_Hilbert_space_filling_curve<3>(points, 5);
 
   for (const auto &p : res)
-    deallog << p[0] << " " << p[1] << " " << p[2] << std::endl;
+    deallog << p[0] << ' ' << p[1] << ' ' << p[2] << std::endl;
 }
 
 
diff --git a/tests/base/utilities_14.cc b/tests/base/utilities_14.cc
index ff61589200..af98ddb8a3 100644
--- a/tests/base/utilities_14.cc
+++ b/tests/base/utilities_14.cc
@@ -59,7 +59,7 @@ test()
     Utilities::inverse_Hilbert_space_filling_curve(points, bit_depth);
 
   for (const auto &p : res)
-    deallog << p[0] << " " << p[1] << " "
+    deallog << p[0] << ' ' << p[1] << ' '
             << Utilities::pack_integers<2>(p, bit_depth) << std::endl;
 }
 
diff --git a/tests/base/utilities_17.cc b/tests/base/utilities_17.cc
index 8346af717b..49ad9bc034 100644
--- a/tests/base/utilities_17.cc
+++ b/tests/base/utilities_17.cc
@@ -74,11 +74,11 @@ test(const unsigned int plane = 1)
     Utilities::inverse_Hilbert_space_filling_curve(points_degenerate,
                                                    bit_depth);
 
-  deallog << plane << ":" << std::endl;
+  deallog << plane << ':' << std::endl;
   for (const auto &p : res)
     {
       AssertThrow(p[0] == 0, ExcInternalError());
-      deallog << p[1] << " " << p[2] << " "
+      deallog << p[1] << ' ' << p[2] << ' '
               << Utilities::pack_integers<3>(p, bit_depth) << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/base/utilities_18.cc b/tests/base/utilities_18.cc
index fd9bb5abf0..0c7e739a2c 100644
--- a/tests/base/utilities_18.cc
+++ b/tests/base/utilities_18.cc
@@ -54,7 +54,7 @@ test(unsigned int plane = 1)
                                                   res[b].end());
             });
 
-  deallog << plane << ":" << std::endl;
+  deallog << plane << ':' << std::endl;
   for (const auto ind : index)
     {
       AssertThrow(res[ind][0] == 0, ExcInternalError());
diff --git a/tests/base/utilities_19.cc b/tests/base/utilities_19.cc
index 3877e93408..1543b861f4 100644
--- a/tests/base/utilities_19.cc
+++ b/tests/base/utilities_19.cc
@@ -39,7 +39,7 @@ test()
   for (unsigned int i = 0; i < res.size(); ++i)
     {
       for (unsigned int d = 0; d < dim; ++d)
-        deallog << " " << res[i][d];
+        deallog << ' ' << res[i][d];
 
       deallog << std::endl;
     }
diff --git a/tests/base/utilities_pack_unpack_03.cc b/tests/base/utilities_pack_unpack_03.cc
index 78381abf50..1552ef6af2 100644
--- a/tests/base/utilities_pack_unpack_03.cc
+++ b/tests/base/utilities_pack_unpack_03.cc
@@ -56,7 +56,7 @@ check(const T &object)
 {
   const std::vector<char> buffer = Utilities::pack(object);
   if (buffer.size() != sizeof(object))
-    deallog << buffer.size() << " should be " << sizeof(object) << "!"
+    deallog << buffer.size() << " should be " << sizeof(object) << '!'
             << std::endl;
   else
     deallog << "same size!" << std::endl;
diff --git a/tests/base/vectorization_05.cc b/tests/base/vectorization_05.cc
index fcc66087ab..37a9529d79 100644
--- a/tests/base/vectorization_05.cc
+++ b/tests/base/vectorization_05.cc
@@ -53,7 +53,7 @@ test()
     for (unsigned int i = 0; i < n_numbers; ++i)
       {
         for (unsigned int j = 0; j < n_vectors; ++j)
-          deallog << arr[i][j] << " ";
+          deallog << arr[i][j] << ' ';
         deallog << std::endl;
       }
 
@@ -69,7 +69,7 @@ test()
     for (unsigned int i = 0; i < n_vectors; ++i)
       {
         for (unsigned int j = 0; j < n_numbers; ++j)
-          deallog << other[i * n_numbers + j] << " ";
+          deallog << other[i * n_numbers + j] << ' ';
         deallog << std::endl;
       }
 
@@ -85,7 +85,7 @@ test()
     for (unsigned int i = 0; i < n_vectors; ++i)
       {
         for (unsigned int j = 0; j < n_numbers; ++j)
-          deallog << other[i * n_numbers + j] << " ";
+          deallog << other[i * n_numbers + j] << ' ';
         deallog << std::endl;
       }
 }
diff --git a/tests/base/vectorization_06.cc b/tests/base/vectorization_06.cc
index 45593b95b8..003fe4acc0 100644
--- a/tests/base/vectorization_06.cc
+++ b/tests/base/vectorization_06.cc
@@ -110,7 +110,7 @@ test()
   if (n_errors > 0)
     {
       for (unsigned int i = 0; i < vec.size(); ++i)
-        deallog << vec[i] << " ";
+        deallog << vec[i] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/base/vectorization_08.cc b/tests/base/vectorization_08.cc
index 92ba8880df..9ddbe06348 100644
--- a/tests/base/vectorization_08.cc
+++ b/tests/base/vectorization_08.cc
@@ -34,6 +34,6 @@ main()
   deallog << "Point norm: " << p.norm()[0] << std::endl;
   SymmetricTensor<2, 3, VectorizedArray<double>> st2;
   SymmetricTensor<4, 2, VectorizedArray<double>> st4;
-  deallog << "Symmetric tensor norm: " << st2.norm()[0] << " " << st4.norm()[0]
+  deallog << "Symmetric tensor norm: " << st2.norm()[0] << ' ' << st4.norm()[0]
           << std::endl;
 }
diff --git a/tests/base/vectorization_10.cc b/tests/base/vectorization_10.cc
index 18cbabae0a..0d6a17c096 100644
--- a/tests/base/vectorization_10.cc
+++ b/tests/base/vectorization_10.cc
@@ -56,7 +56,7 @@ do_test()
       for (unsigned int i = 0; i < n_numbers; ++i)
         {
           for (unsigned int j = 0; j < n_vectors; ++j)
-            deallog << arr[i][j] << " ";
+            deallog << arr[i][j] << ' ';
           deallog << std::endl;
         }
     }
@@ -75,7 +75,7 @@ do_test()
       for (unsigned int i = 0; i < n_vectors; ++i)
         {
           for (unsigned int j = 0; j < n_numbers; ++j)
-            deallog << other[i * n_numbers + j] << " ";
+            deallog << other[i * n_numbers + j] << ' ';
           deallog << std::endl;
         }
     }
@@ -94,7 +94,7 @@ do_test()
       for (unsigned int i = 0; i < n_vectors; ++i)
         {
           for (unsigned int j = 0; j < n_numbers; ++j)
-            deallog << other[i * n_numbers + j] << " ";
+            deallog << other[i * n_numbers + j] << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/base/vectorization_12.cc b/tests/base/vectorization_12.cc
index 3f1554a4ef..a0f43b101e 100644
--- a/tests/base/vectorization_12.cc
+++ b/tests/base/vectorization_12.cc
@@ -38,7 +38,7 @@ test()
   std::stringstream reference_stream;
   for (unsigned int i = 0; i < n - 1; ++i)
     {
-      reference_stream << Number(i + 1) << " ";
+      reference_stream << Number(i + 1) << ' ';
     }
   reference_stream << Number(n);
 
diff --git a/tests/base/vectorization_13.cc b/tests/base/vectorization_13.cc
index ab84e66ed6..041756449e 100644
--- a/tests/base/vectorization_13.cc
+++ b/tests/base/vectorization_13.cc
@@ -32,7 +32,7 @@ do_test(const VectorizedArrayType                      array,
   auto exponentiated_array = std::pow(array, number);
 
   for (unsigned int i = 0; i < VectorizedArrayType::size(); ++i)
-    deallog << exponentiated_array[i] << " ";
+    deallog << exponentiated_array[i] << ' ';
   deallog << std::endl;
 }
 
@@ -47,7 +47,7 @@ do_test(const VectorizedArrayType array, const VectorizedArrayType number)
   auto exponentiated_array = std::pow(array, number);
 
   for (unsigned int i = 0; i < VectorizedArrayType::size(); ++i)
-    deallog << exponentiated_array[i] << " ";
+    deallog << exponentiated_array[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/base/vectorization_15.cc b/tests/base/vectorization_15.cc
index 8c1d441da1..34c3ac054d 100644
--- a/tests/base/vectorization_15.cc
+++ b/tests/base/vectorization_15.cc
@@ -62,7 +62,7 @@ do_test()
       for (unsigned int i = 0; i < n_numbers; ++i)
         {
           for (unsigned int j = 0; j < n_vectors; ++j)
-            deallog << arr[i][j] << " ";
+            deallog << arr[i][j] << ' ';
           deallog << std::endl;
         }
     }
@@ -84,7 +84,7 @@ do_test()
       for (unsigned int i = 0; i < n_vectors; ++i)
         {
           for (unsigned int j = 0; j < n_numbers; ++j)
-            deallog << other[i * n_numbers + j] << " ";
+            deallog << other[i * n_numbers + j] << ' ';
           deallog << std::endl;
         }
     }
@@ -106,7 +106,7 @@ do_test()
       for (unsigned int i = 0; i < n_vectors; ++i)
         {
           for (unsigned int j = 0; j < n_numbers; ++j)
-            deallog << other[i * n_numbers + j] << " ";
+            deallog << other[i * n_numbers + j] << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/bits/anna_4.cc b/tests/bits/anna_4.cc
index 87ff66f3c9..cdaee0d017 100644
--- a/tests/bits/anna_4.cc
+++ b/tests/bits/anna_4.cc
@@ -229,7 +229,7 @@ FindBug<dim>::dirichlet_conditions()
                                            component_mask);
   for (unsigned int i = 0; i < dof_handler.n_dofs(); ++i)
     if (fixed_dofs[i] == true)
-      deallog << i << " " << dirichlet_dofs[i] << std::endl;
+      deallog << i << ' ' << dirichlet_dofs[i] << std::endl;
 }
 
 
diff --git a/tests/bits/apply_boundary_values_01.cc b/tests/bits/apply_boundary_values_01.cc
index 7612c74712..5fc2528a7b 100644
--- a/tests/bits/apply_boundary_values_01.cc
+++ b/tests/bits/apply_boundary_values_01.cc
@@ -46,7 +46,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/bits/apply_boundary_values_02.cc b/tests/bits/apply_boundary_values_02.cc
index cbb96c6c83..b58ec3c158 100644
--- a/tests/bits/apply_boundary_values_02.cc
+++ b/tests/bits/apply_boundary_values_02.cc
@@ -46,7 +46,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/bits/block_sparse_matrix_iterator_01.cc b/tests/bits/block_sparse_matrix_iterator_01.cc
index d33f8a6b32..52ebde9248 100644
--- a/tests/bits/block_sparse_matrix_iterator_01.cc
+++ b/tests/bits/block_sparse_matrix_iterator_01.cc
@@ -41,7 +41,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/bits/chunk_sparse_matrix_11.cc b/tests/bits/chunk_sparse_matrix_11.cc
index eae63a2643..d255193c8c 100644
--- a/tests/bits/chunk_sparse_matrix_11.cc
+++ b/tests/bits/chunk_sparse_matrix_11.cc
@@ -53,7 +53,7 @@ test(const unsigned int chunk_size)
            it != m.end(i);
            ++it)
         {
-          deallog << "[" << it->column() << "," << std::setprecision(2)
+          deallog << '[' << it->column() << ',' << std::setprecision(2)
                   << std::fixed << std::setw(4) << it->value() << "] ";
         }
       deallog << std::endl;
diff --git a/tests/bits/chunk_sparse_matrix_12.cc b/tests/bits/chunk_sparse_matrix_12.cc
index 1e69ebf582..fb0fa58e37 100644
--- a/tests/bits/chunk_sparse_matrix_12.cc
+++ b/tests/bits/chunk_sparse_matrix_12.cc
@@ -53,7 +53,7 @@ test(const unsigned int chunk_size)
            it != m.end(i);
            ++it)
         {
-          deallog << "[" << it->column() << "," << std::setprecision(2)
+          deallog << '[' << it->column() << ',' << std::setprecision(2)
                   << std::fixed << std::setw(4) << it->value() << "] ";
         }
       deallog << std::endl;
diff --git a/tests/bits/chunk_sparse_matrix_13.cc b/tests/bits/chunk_sparse_matrix_13.cc
index 619a390c9f..ad60372fa3 100644
--- a/tests/bits/chunk_sparse_matrix_13.cc
+++ b/tests/bits/chunk_sparse_matrix_13.cc
@@ -53,7 +53,7 @@ test(const unsigned int chunk_size)
            it != m.end(i);
            ++it)
         {
-          deallog << "[" << it->column() << "," << std::setprecision(2)
+          deallog << '[' << it->column() << ',' << std::setprecision(2)
                   << std::fixed << std::setw(4) << it->value() << "] ";
         }
       deallog << std::endl;
diff --git a/tests/bits/distorted_cells_01.cc b/tests/bits/distorted_cells_01.cc
index 28833dcb1e..e9b56033d3 100644
--- a/tests/bits/distorted_cells_01.cc
+++ b/tests/bits/distorted_cells_01.cc
@@ -48,11 +48,11 @@ check(const unsigned int testcase)
   switch (testcase)
     {
       case 1:
-        deallog << "Pinched cell in " << dim << "d" << std::endl;
+        deallog << "Pinched cell in " << dim << 'd' << std::endl;
         vertices[0] = vertices[1];
         break;
       case 2:
-        deallog << "Twisted cell in " << dim << "d" << std::endl;
+        deallog << "Twisted cell in " << dim << 'd' << std::endl;
         std::swap(vertices[0], vertices[1]);
         break;
       default:
diff --git a/tests/bits/distorted_cells_07.cc b/tests/bits/distorted_cells_07.cc
index 0b47b7fcfc..599d870b32 100644
--- a/tests/bits/distorted_cells_07.cc
+++ b/tests/bits/distorted_cells_07.cc
@@ -48,7 +48,7 @@ check(const unsigned int testcase)
   switch (testcase)
     {
       case 2:
-        deallog << "Twisted cell in " << dim << "d" << std::endl;
+        deallog << "Twisted cell in " << dim << 'd' << std::endl;
         std::swap(vertices[1], vertices[0]);
         break;
       default:
diff --git a/tests/bits/fe_field_function_03.cc b/tests/bits/fe_field_function_03.cc
index 3f7d8d03e5..f4246217b1 100644
--- a/tests/bits/fe_field_function_03.cc
+++ b/tests/bits/fe_field_function_03.cc
@@ -79,8 +79,8 @@ test()
   ff.laplacian_list(vec, values_c);
   fef.laplacian_list(vec, values_a);
   deallog << "Value of the laplacian in 0.5*e1 and 0.25 * e1:" << std::endl;
-  deallog << " correct values: " << values_c[0] << " " << values_c[1]
-          << ", approximations: " << values_a[0] << " " << values_a[1]
+  deallog << " correct values: " << values_c[0] << ' ' << values_c[1]
+          << ", approximations: " << values_a[0] << ' ' << values_a[1]
           << std::endl;
 }
 
diff --git a/tests/bits/fe_tools_01a.cc b/tests/bits/fe_tools_01a.cc
index 012fc5a405..0bc236ae0b 100644
--- a/tests/bits/fe_tools_01a.cc
+++ b/tests/bits/fe_tools_01a.cc
@@ -45,7 +45,7 @@ check(const FE_Q<dim> &fe, const std::string &name)
   const std::vector<unsigned int> n =
     FETools::lexicographic_to_hierarchic_numbering<dim>(fe.degree);
   for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-    deallog << n[i] << " ";
+    deallog << n[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/bits/fe_tools_01b.cc b/tests/bits/fe_tools_01b.cc
index eb0135b1ed..d2e25c3ce7 100644
--- a/tests/bits/fe_tools_01b.cc
+++ b/tests/bits/fe_tools_01b.cc
@@ -45,7 +45,7 @@ check(const FE_Q<dim> &fe, const std::string &name)
   const std::vector<unsigned int> n =
     FETools::hierarchic_to_lexicographic_numbering<dim>(fe.degree);
   for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-    deallog << n[i] << " ";
+    deallog << n[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/bits/fe_tools_01c.cc b/tests/bits/fe_tools_01c.cc
index 40777ab882..dcf4fc38fe 100644
--- a/tests/bits/fe_tools_01c.cc
+++ b/tests/bits/fe_tools_01c.cc
@@ -57,7 +57,7 @@ check(const FE_Q<dim> &fe, const std::string &name)
       Assert(n1[n2[i]] == i, ExcInternalError());
       Assert(n2[n1[i]] == i, ExcInternalError());
 
-      deallog << n1[n2[i]] << " ";
+      deallog << n1[n2[i]] << ' ';
     }
   deallog << std::endl;
 }
diff --git a/tests/bits/find_cell_1.cc b/tests/bits/find_cell_1.cc
index 30d567811f..b85db0976b 100644
--- a/tests/bits/find_cell_1.cc
+++ b/tests/bits/find_cell_1.cc
@@ -39,7 +39,7 @@ check(Triangulation<2> &tria)
 
   deallog << cell << std::endl;
   for (const unsigned int v : GeometryInfo<2>::vertex_indices())
-    deallog << "<" << cell->vertex(v) << "> ";
+    deallog << '<' << cell->vertex(v) << "> ";
   deallog << std::endl;
 
   Assert(p.distance(cell->center()) < cell->diameter() / 2, ExcInternalError());
diff --git a/tests/bits/find_cell_2.cc b/tests/bits/find_cell_2.cc
index a319d8413d..337b8d2ccd 100644
--- a/tests/bits/find_cell_2.cc
+++ b/tests/bits/find_cell_2.cc
@@ -38,7 +38,7 @@ check(Triangulation<3> &tria)
 
   deallog << cell << std::endl;
   for (const unsigned int v : GeometryInfo<3>::vertex_indices())
-    deallog << "<" << cell->vertex(v) << "> ";
+    deallog << '<' << cell->vertex(v) << "> ";
   deallog << std::endl;
 
   Assert(p.distance(cell->center()) < cell->diameter() / 2, ExcInternalError());
diff --git a/tests/bits/find_cell_3.cc b/tests/bits/find_cell_3.cc
index 181a1e5478..6e388999de 100644
--- a/tests/bits/find_cell_3.cc
+++ b/tests/bits/find_cell_3.cc
@@ -40,7 +40,7 @@ check(Triangulation<3> &tria)
 
   deallog << cell << std::endl;
   for (const unsigned int v : GeometryInfo<3>::vertex_indices())
-    deallog << "<" << cell->vertex(v) << "> ";
+    deallog << '<' << cell->vertex(v) << "> ";
   deallog << std::endl;
 
   Assert(p.distance(cell->center()) < cell->diameter() / 2, ExcInternalError());
diff --git a/tests/bits/find_cell_4.cc b/tests/bits/find_cell_4.cc
index 29b9d15394..f8f3375eaf 100644
--- a/tests/bits/find_cell_4.cc
+++ b/tests/bits/find_cell_4.cc
@@ -40,7 +40,7 @@ check(Triangulation<3> &tria)
 
   deallog << cell << std::endl;
   for (const unsigned int v : GeometryInfo<3>::vertex_indices())
-    deallog << "<" << cell->vertex(v) << "> ";
+    deallog << '<' << cell->vertex(v) << "> ";
   deallog << std::endl;
 
   // Transform back and forth
diff --git a/tests/bits/find_cell_5.cc b/tests/bits/find_cell_5.cc
index 4bb4c745aa..05f2a4f333 100644
--- a/tests/bits/find_cell_5.cc
+++ b/tests/bits/find_cell_5.cc
@@ -42,7 +42,7 @@ check(Triangulation<3> &tria)
 
   deallog << cell << std::endl;
   for (const unsigned int v : GeometryInfo<3>::vertex_indices())
-    deallog << "<" << cell->vertex(v) << "> ";
+    deallog << '<' << cell->vertex(v) << "> ";
   deallog << std::endl;
 
   // Transform back and forth
diff --git a/tests/bits/find_cell_8.cc b/tests/bits/find_cell_8.cc
index 1fccac5cc7..b3d699ce91 100644
--- a/tests/bits/find_cell_8.cc
+++ b/tests/bits/find_cell_8.cc
@@ -73,7 +73,7 @@ check(Triangulation<2> &tria)
 
   deallog << cell << std::endl;
   for (const unsigned int v : GeometryInfo<2>::vertex_indices())
-    deallog << "<" << cell->vertex(v) << "> ";
+    deallog << '<' << cell->vertex(v) << "> ";
   deallog << std::endl;
 
   AssertThrow(p.distance(cell->center()) < cell->diameter() / 2,
diff --git a/tests/bits/find_cell_9.cc b/tests/bits/find_cell_9.cc
index af0e63891e..2cd05fedb0 100644
--- a/tests/bits/find_cell_9.cc
+++ b/tests/bits/find_cell_9.cc
@@ -76,7 +76,7 @@ check(Triangulation<2> &tria)
 
   deallog << cell << std::endl;
   for (const unsigned int v : GeometryInfo<2>::vertex_indices())
-    deallog << "<" << cell->vertex(v) << "> ";
+    deallog << '<' << cell->vertex(v) << "> ";
   deallog << std::endl;
 
   AssertThrow(p.distance(cell->center()) < cell->diameter() / 2,
diff --git a/tests/bits/find_cell_alt_1.cc b/tests/bits/find_cell_alt_1.cc
index 86696fe05d..cdb42f798b 100644
--- a/tests/bits/find_cell_alt_1.cc
+++ b/tests/bits/find_cell_alt_1.cc
@@ -44,7 +44,7 @@ check(Triangulation<2> &tria)
 
   deallog << cell.first << std::endl;
   for (const unsigned int v : GeometryInfo<2>::vertex_indices())
-    deallog << "<" << cell.first->vertex(v) << "> ";
+    deallog << '<' << cell.first->vertex(v) << "> ";
   deallog << "[ " << cell.second << "] ";
   deallog << std::endl;
 
diff --git a/tests/bits/find_cell_alt_2.cc b/tests/bits/find_cell_alt_2.cc
index 86ca4ecc78..54cc34ed86 100644
--- a/tests/bits/find_cell_alt_2.cc
+++ b/tests/bits/find_cell_alt_2.cc
@@ -42,7 +42,7 @@ check(Triangulation<3> &tria)
 
   deallog << cell.first << std::endl;
   for (const unsigned int v : GeometryInfo<3>::vertex_indices())
-    deallog << "<" << cell.first->vertex(v) << "> " << std::endl;
+    deallog << '<' << cell.first->vertex(v) << "> " << std::endl;
   deallog << "[ " << cell.second << "] ";
 
   deallog << std::endl << std::endl;
diff --git a/tests/bits/find_cell_alt_3.cc b/tests/bits/find_cell_alt_3.cc
index 7abd908516..7ff5d2dd1d 100644
--- a/tests/bits/find_cell_alt_3.cc
+++ b/tests/bits/find_cell_alt_3.cc
@@ -44,7 +44,7 @@ check(Triangulation<3> &tria)
 
   deallog << cell.first << std::endl;
   for (const unsigned int v : GeometryInfo<3>::vertex_indices())
-    deallog << "<" << cell.first->vertex(v) << "> ";
+    deallog << '<' << cell.first->vertex(v) << "> ";
   deallog << "[ " << cell.second << "] ";
   deallog << std::endl;
 
diff --git a/tests/bits/find_cell_alt_4.cc b/tests/bits/find_cell_alt_4.cc
index e8ba9db79a..8b4cc406c7 100644
--- a/tests/bits/find_cell_alt_4.cc
+++ b/tests/bits/find_cell_alt_4.cc
@@ -42,7 +42,7 @@ check(Triangulation<3> &tria)
 
   deallog << cell.first << std::endl;
   for (const unsigned int v : GeometryInfo<3>::vertex_indices())
-    deallog << "<" << cell.first->vertex(v) << "> ";
+    deallog << '<' << cell.first->vertex(v) << "> ";
   deallog << "[ " << cell.second << "] ";
   deallog << std::endl;
 
diff --git a/tests/bits/find_cell_alt_5.cc b/tests/bits/find_cell_alt_5.cc
index d78720c563..2c26fe27cb 100644
--- a/tests/bits/find_cell_alt_5.cc
+++ b/tests/bits/find_cell_alt_5.cc
@@ -41,7 +41,7 @@ check(Triangulation<3> &tria)
 
   deallog << cell.first << std::endl;
   for (const unsigned int v : GeometryInfo<3>::vertex_indices())
-    deallog << "<" << cell.first->vertex(v) << "> ";
+    deallog << '<' << cell.first->vertex(v) << "> ";
   deallog << "[ " << cell.second << "] ";
   deallog << std::endl;
 
diff --git a/tests/bits/find_cell_alt_6.cc b/tests/bits/find_cell_alt_6.cc
index aade2a7759..f6e4c3ad23 100644
--- a/tests/bits/find_cell_alt_6.cc
+++ b/tests/bits/find_cell_alt_6.cc
@@ -54,8 +54,8 @@ check(Triangulation<2> &tria)
 
       deallog << "Vertex <" << v[i] << "> found in cell ";
       for (const unsigned int v : GeometryInfo<2>::vertex_indices())
-        deallog << "<" << cell.first->vertex(v) << "> ";
-      deallog << " [local: " << cell.second << "]" << std::endl;
+        deallog << '<' << cell.first->vertex(v) << "> ";
+      deallog << " [local: " << cell.second << ']' << std::endl;
     }
 }
 
diff --git a/tests/bits/find_cells_adjacent_to_vertex_1.cc b/tests/bits/find_cells_adjacent_to_vertex_1.cc
index 03e7502891..3175eb6af5 100644
--- a/tests/bits/find_cells_adjacent_to_vertex_1.cc
+++ b/tests/bits/find_cells_adjacent_to_vertex_1.cc
@@ -53,7 +53,7 @@ check(Triangulation<2> &tria)
       for (unsigned c = 0; c < cells.size(); ++c)
         {
           for (const unsigned int v : GeometryInfo<2>::vertex_indices())
-            deallog << "<" << cells[c]->vertex(v) << "> ";
+            deallog << '<' << cells[c]->vertex(v) << "> ";
           deallog << std::endl;
         }
     }
diff --git a/tests/bits/find_closest_vertex_1.cc b/tests/bits/find_closest_vertex_1.cc
index b839dc59b9..924ef554ef 100644
--- a/tests/bits/find_closest_vertex_1.cc
+++ b/tests/bits/find_closest_vertex_1.cc
@@ -35,7 +35,7 @@ check(Triangulation<3> &tria)
 {
   const std::vector<Point<3>> &v = tria.get_vertices();
   for (unsigned i = 0; i < v.size(); ++i)
-    deallog << "["
+    deallog << '['
             << GridTools::find_closest_vertex(tria,
                                               v[i] +
                                                 Point<3>(0.01, -0.01, 0.01))
diff --git a/tests/bits/make_boundary_constraints_01.cc b/tests/bits/make_boundary_constraints_01.cc
index 32f21606da..d8fd84f05c 100644
--- a/tests/bits/make_boundary_constraints_01.cc
+++ b/tests/bits/make_boundary_constraints_01.cc
@@ -47,7 +47,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/bits/make_boundary_constraints_02.cc b/tests/bits/make_boundary_constraints_02.cc
index e452176636..8fd2bd47e5 100644
--- a/tests/bits/make_boundary_constraints_02.cc
+++ b/tests/bits/make_boundary_constraints_02.cc
@@ -50,7 +50,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   const Point<dim>   p2 =
diff --git a/tests/bits/map_dofs_to_support_points_hp_01.cc b/tests/bits/map_dofs_to_support_points_hp_01.cc
index 70366e9ec4..67af7ebf21 100644
--- a/tests/bits/map_dofs_to_support_points_hp_01.cc
+++ b/tests/bits/map_dofs_to_support_points_hp_01.cc
@@ -70,7 +70,7 @@ test()
     {
       // both maps should contain the same
       Assert(hp_map[i] == map[i], ExcInternalError());
-      deallog << hp_map[i] << " ";
+      deallog << hp_map[i] << ' ';
     }
   deallog << std::endl;
 }
diff --git a/tests/bits/periodicity_01.cc b/tests/bits/periodicity_01.cc
index 657c0558e6..8602976859 100644
--- a/tests/bits/periodicity_01.cc
+++ b/tests/bits/periodicity_01.cc
@@ -60,7 +60,7 @@ test()
     (std::next(dof_handler.begin(0)))->face(1),
     cm);
 
-  deallog << "dim " << std::to_string(dim) << ":" << std::endl;
+  deallog << "dim " << std::to_string(dim) << ':' << std::endl;
   cm.print(deallog.get_file_stream());
 }
 
diff --git a/tests/bits/periodicity_02.cc b/tests/bits/periodicity_02.cc
index 2d5d2f07aa..1bdd0c2611 100644
--- a/tests/bits/periodicity_02.cc
+++ b/tests/bits/periodicity_02.cc
@@ -40,7 +40,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   // create a 2x1 (or 2x1x1) mesh and refine the leftmost cell
   Triangulation<dim>        triangulation;
diff --git a/tests/bits/periodicity_03.cc b/tests/bits/periodicity_03.cc
index 5f7191aedb..17f3918ed2 100644
--- a/tests/bits/periodicity_03.cc
+++ b/tests/bits/periodicity_03.cc
@@ -40,7 +40,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   // create a 2x1 (or 2x1x1) mesh and refine the leftmost cell twice
   Triangulation<dim>        triangulation;
diff --git a/tests/bits/periodicity_04.cc b/tests/bits/periodicity_04.cc
index 17f57245c7..33c1a4698b 100644
--- a/tests/bits/periodicity_04.cc
+++ b/tests/bits/periodicity_04.cc
@@ -44,7 +44,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   // create a 2x1 (or 2x1x1) mesh and refine the leftmost cell twice
   Triangulation<dim>        triangulation;
diff --git a/tests/bits/periodicity_09.cc b/tests/bits/periodicity_09.cc
index 728f5c60bb..1a870aeb18 100644
--- a/tests/bits/periodicity_09.cc
+++ b/tests/bits/periodicity_09.cc
@@ -42,7 +42,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   // create a 2x1 (or 2x1x1) mesh and refine the leftmost cell
   Triangulation<dim>        triangulation;
diff --git a/tests/bits/refine_and_coarsen_for_active_cell_index.cc b/tests/bits/refine_and_coarsen_for_active_cell_index.cc
index 3ec4c83277..b782460457 100644
--- a/tests/bits/refine_and_coarsen_for_active_cell_index.cc
+++ b/tests/bits/refine_and_coarsen_for_active_cell_index.cc
@@ -116,7 +116,7 @@ check()
 
   check(tria);
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/bits/refine_and_coarsen_for_active_cell_index_02.cc b/tests/bits/refine_and_coarsen_for_active_cell_index_02.cc
index 4510d11dfb..2b5e443525 100644
--- a/tests/bits/refine_and_coarsen_for_active_cell_index_02.cc
+++ b/tests/bits/refine_and_coarsen_for_active_cell_index_02.cc
@@ -120,7 +120,7 @@ check()
 
   check(tria);
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/bits/refine_and_coarsen_for_active_cell_index_03.cc b/tests/bits/refine_and_coarsen_for_active_cell_index_03.cc
index 7b930a92bd..e05da997de 100644
--- a/tests/bits/refine_and_coarsen_for_active_cell_index_03.cc
+++ b/tests/bits/refine_and_coarsen_for_active_cell_index_03.cc
@@ -119,7 +119,7 @@ check()
 
   check(tria);
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/bits/refine_and_coarsen_for_active_cell_index_04.cc b/tests/bits/refine_and_coarsen_for_active_cell_index_04.cc
index a8fd2c904f..3df3b1fbf3 100644
--- a/tests/bits/refine_and_coarsen_for_active_cell_index_04.cc
+++ b/tests/bits/refine_and_coarsen_for_active_cell_index_04.cc
@@ -132,7 +132,7 @@ check()
     check(x);
   }
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/bits/refine_and_coarsen_for_active_cell_index_05.cc b/tests/bits/refine_and_coarsen_for_active_cell_index_05.cc
index e8feccbfd0..54aab96b50 100644
--- a/tests/bits/refine_and_coarsen_for_active_cell_index_05.cc
+++ b/tests/bits/refine_and_coarsen_for_active_cell_index_05.cc
@@ -165,7 +165,7 @@ check()
     check(x);
   }
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/bits/refine_and_coarsen_for_parents.cc b/tests/bits/refine_and_coarsen_for_parents.cc
index 18473eb863..c7c04aa2f6 100644
--- a/tests/bits/refine_and_coarsen_for_parents.cc
+++ b/tests/bits/refine_and_coarsen_for_parents.cc
@@ -114,7 +114,7 @@ check()
     for (unsigned int child = 0; child < cell->n_children(); ++child)
       AssertThrow(cell->child(child)->parent() == cell, ExcInternalError());
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/bits/refine_and_coarsen_for_parents_02.cc b/tests/bits/refine_and_coarsen_for_parents_02.cc
index 1389c60925..c94f101d6e 100644
--- a/tests/bits/refine_and_coarsen_for_parents_02.cc
+++ b/tests/bits/refine_and_coarsen_for_parents_02.cc
@@ -116,7 +116,7 @@ check()
     for (unsigned int child = 0; child < cell->n_children(); ++child)
       AssertThrow(cell->child(child)->parent() == cell, ExcInternalError());
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/bits/refine_and_coarsen_for_parents_03.cc b/tests/bits/refine_and_coarsen_for_parents_03.cc
index 9266ebfc2d..7c51055b5b 100644
--- a/tests/bits/refine_and_coarsen_for_parents_03.cc
+++ b/tests/bits/refine_and_coarsen_for_parents_03.cc
@@ -115,7 +115,7 @@ check()
     for (unsigned int child = 0; child < cell->n_children(); ++child)
       AssertThrow(cell->child(child)->parent() == cell, ExcInternalError());
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/bits/step-11.cc b/tests/bits/step-11.cc
index 815e118ff0..958aee0d7b 100644
--- a/tests/bits/step-11.cc
+++ b/tests/bits/step-11.cc
@@ -90,7 +90,7 @@ LaplaceProblem<dim>::LaplaceProblem(const unsigned int mapping_degree)
   , dof_handler(triangulation)
   , mapping(mapping_degree)
 {
-  deallog << "Using mapping with degree " << mapping_degree << ":" << std::endl
+  deallog << "Using mapping with degree " << mapping_degree << ':' << std::endl
           << "============================" << std::endl;
 }
 
diff --git a/tests/bits/step-13.cc b/tests/bits/step-13.cc
index dd98491733..b65ada23b4 100644
--- a/tests/bits/step-13.cc
+++ b/tests/bits/step-13.cc
@@ -188,7 +188,7 @@ namespace Evaluation
     //     data_out.build_patches ();
 
     //     std::ostringstream filename;
-    //     filename << output_name_base << "-"
+    //     filename << output_name_base << '-'
     //       << this->refinement_cycle
     //       << data_out.default_suffix (output_format)
     //       << std::ends;
@@ -718,7 +718,7 @@ run_simulation(
 
   for (unsigned int step = 0; true; ++step)
     {
-      deallog << step << " " << std::flush;
+      deallog << step << ' ' << std::flush;
 
       solver.solve_problem();
 
diff --git a/tests/bits/step-14.cc b/tests/bits/step-14.cc
index e726c69985..a898faa5e7 100644
--- a/tests/bits/step-14.cc
+++ b/tests/bits/step-14.cc
@@ -248,7 +248,7 @@ namespace Evaluation
                               const Vector<double> & /*solution*/) const
   {
     std::ostringstream filename;
-    filename << output_name_base << "-" << this->refinement_cycle << ".eps"
+    filename << output_name_base << '-' << this->refinement_cycle << ".eps"
              << std::ends;
 
     GridOut().write_eps(dof_handler.get_triangulation(),
diff --git a/tests/bits/unit_support_points.cc b/tests/bits/unit_support_points.cc
index 83055d1432..1fd7071e4f 100644
--- a/tests/bits/unit_support_points.cc
+++ b/tests/bits/unit_support_points.cc
@@ -74,7 +74,7 @@ check_cell2(const FiniteElement<dim> &fe, const unsigned int comp)
 {
   for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
     if (fe.system_to_component_index(i).first == comp)
-      deallog << i << " " << fe.unit_support_point(i) << std::endl;
+      deallog << i << ' ' << fe.unit_support_point(i) << std::endl;
   deallog << "dim=" << dim << ", cell=ok" << std::endl;
 }
 
@@ -85,7 +85,7 @@ check_face2(const FiniteElement<dim> &fe, const unsigned int comp)
 {
   for (unsigned int i = 0; i < fe.dofs_per_face; ++i)
     if (fe.face_system_to_component_index(i).first == comp)
-      deallog << i << " " << fe.unit_face_support_point(i) << std::endl;
+      deallog << i << ' ' << fe.unit_face_support_point(i) << std::endl;
   deallog << "dim=" << dim << ", face=ok" << std::endl;
 }
 
diff --git a/tests/boost/extract_representative_set_02.cc b/tests/boost/extract_representative_set_02.cc
index f2c9867043..03ee5b2e0b 100644
--- a/tests/boost/extract_representative_set_02.cc
+++ b/tests/boost/extract_representative_set_02.cc
@@ -43,9 +43,9 @@ print(const BoundingBox<2> &box)
   const auto p2 = p.second;
 
   str << p1 << std::endl
-      << p2[0] << " " << p1[1] << std::endl
+      << p2[0] << ' ' << p1[1] << std::endl
       << p2 << std::endl
-      << p1[0] << " " << p2[1] << std::endl
+      << p1[0] << ' ' << p2[1] << std::endl
       << p1 << std::endl;
   return str.str();
 }
diff --git a/tests/codim_one/grid_in_out_03.cc b/tests/codim_one/grid_in_out_03.cc
index a36df29390..21c1d89788 100644
--- a/tests/codim_one/grid_in_out_03.cc
+++ b/tests/codim_one/grid_in_out_03.cc
@@ -32,7 +32,7 @@ void
 test(std::string filename)
 {
   deallog.get_file_stream()
-    << " Tria<" << dim << "," << spacedim << ">: " << std::endl;
+    << " Tria<" << dim << ',' << spacedim << ">: " << std::endl;
   Triangulation<dim, spacedim> tria;
   GridIn<dim, spacedim>        gi;
   gi.attach_triangulation(tria);
diff --git a/tests/codim_one/hanging_nodes_02.cc b/tests/codim_one/hanging_nodes_02.cc
index b5b24de8f6..8489f07dc1 100644
--- a/tests/codim_one/hanging_nodes_02.cc
+++ b/tests/codim_one/hanging_nodes_02.cc
@@ -71,7 +71,7 @@ main()
       for (const unsigned int face : GeometryInfo<dim>::face_indices())
         {
           deallog << "  face = " << face
-                  << "  (neighbor = " << cell->neighbor(face) << ")"
+                  << "  (neighbor = " << cell->neighbor(face) << ')'
                   << std::endl;
 
           if (cell->face(face)->has_children())
diff --git a/tests/codim_one/hanging_nodes_03.cc b/tests/codim_one/hanging_nodes_03.cc
index 80620f2240..9be79f496a 100644
--- a/tests/codim_one/hanging_nodes_03.cc
+++ b/tests/codim_one/hanging_nodes_03.cc
@@ -63,7 +63,7 @@ main()
       for (const unsigned int face : GeometryInfo<dim>::face_indices())
         {
           deallog << "  face = " << face
-                  << "  (neighbor = " << cell->neighbor(face) << ")"
+                  << "  (neighbor = " << cell->neighbor(face) << ')'
                   << std::endl;
 
           if (cell->face(face)->has_children())
diff --git a/tests/codim_one/integrate_log.cc b/tests/codim_one/integrate_log.cc
index 6c8029d877..878c3098ad 100644
--- a/tests/codim_one/integrate_log.cc
+++ b/tests/codim_one/integrate_log.cc
@@ -142,7 +142,7 @@ main()
 
   deallog
     << "Calculation of the integral of ln(x-a)*f(x) on the interval [a,b] = ["
-    << a << ", " << b << "]" << std::endl;
+    << a << ", " << b << ']' << std::endl;
   for (unsigned int j = 0; j < 13; ++j)
     {
       exact_integral = 0;
diff --git a/tests/codim_one/measure_of_distorted_codim_one_face.cc b/tests/codim_one/measure_of_distorted_codim_one_face.cc
index 9ae5eedc3a..b33aada526 100644
--- a/tests/codim_one/measure_of_distorted_codim_one_face.cc
+++ b/tests/codim_one/measure_of_distorted_codim_one_face.cc
@@ -78,7 +78,7 @@ test()
   if (std::abs(sum_1 - sum_2) < tol)
     deallog << "Test passed" << std::endl;
   else
-    deallog << sum_1 << " " << sum_2 << std::endl;
+    deallog << sum_1 << ' ' << sum_2 << std::endl;
   deallog << std::endl;
 }
 
diff --git a/tests/codim_one/tensor_matrix_conversion.cc b/tests/codim_one/tensor_matrix_conversion.cc
index 018a675cb8..8c8241a6db 100644
--- a/tests/codim_one/tensor_matrix_conversion.cc
+++ b/tests/codim_one/tensor_matrix_conversion.cc
@@ -38,11 +38,11 @@ template <typename number>
 void
 display_matrix(FullMatrix<number> M)
 {
-  deallog << M.m() << "x" << M.n() << " matrix" << std::endl;
+  deallog << M.m() << 'x' << M.n() << " matrix" << std::endl;
   for (unsigned int i = 0; i < M.m(); ++i)
     {
       for (unsigned int j = 0; j < M.n(); ++j)
-        deallog << M(i, j) << " ";
+        deallog << M(i, j) << ' ';
       deallog << std::endl;
     }
 }
@@ -61,11 +61,11 @@ template <int b>
 void
 display_tensor_2(Tensor<2, b> &T)
 {
-  deallog << b << "x" << b << " tensor" << std::endl;
+  deallog << b << 'x' << b << " tensor" << std::endl;
   for (unsigned int i = 0; i < b; ++i)
     {
       for (unsigned int j = 0; j < b; ++j)
-        deallog << T[i][j] << " ";
+        deallog << T[i][j] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/data_out/data_out_base_vtu_compression_levels.cc b/tests/data_out/data_out_base_vtu_compression_levels.cc
index 7d339c92bb..ca4a3e7cca 100644
--- a/tests/data_out/data_out_base_vtu_compression_levels.cc
+++ b/tests/data_out/data_out_base_vtu_compression_levels.cc
@@ -78,7 +78,7 @@ check_all(std::ostream &log)
             Assert(false, ExcInternalError());
         }
       log << "==============================\n"
-          << dim << spacedim << "-" << flags.compression_level << ".vtu"
+          << dim << spacedim << '-' << flags.compression_level << ".vtu"
           << "\n==============================\n";
       check<dim, spacedim>(flags, log);
     }
diff --git a/tests/distributed_grids/2d_dofhandler_01.cc b/tests/distributed_grids/2d_dofhandler_01.cc
index 7aae26f6f2..aeb65503f5 100644
--- a/tests/distributed_grids/2d_dofhandler_01.cc
+++ b/tests/distributed_grids/2d_dofhandler_01.cc
@@ -66,7 +66,7 @@ test()
       cell->get_dof_indices(local_dof_indices);
 
       for (unsigned int i = 0; i < dofs_per_cell; ++i)
-        deallog << local_dof_indices[i] << " ";
+        deallog << local_dof_indices[i] << ' ';
 
       deallog << std::endl;
     }
diff --git a/tests/distributed_grids/get_boundary_ids_01.cc b/tests/distributed_grids/get_boundary_ids_01.cc
index aa0ff97e4f..05948dff82 100644
--- a/tests/distributed_grids/get_boundary_ids_01.cc
+++ b/tests/distributed_grids/get_boundary_ids_01.cc
@@ -44,7 +44,7 @@ test()
         }
 
   for (const auto i : tria.get_boundary_ids())
-    deallog << i << " ";
+    deallog << i << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/distributed_grids/grid_tools_exchange_cell_data_01.cc b/tests/distributed_grids/grid_tools_exchange_cell_data_01.cc
index 77366e8dc5..df2f4aaa47 100644
--- a/tests/distributed_grids/grid_tools_exchange_cell_data_01.cc
+++ b/tests/distributed_grids/grid_tools_exchange_cell_data_01.cc
@@ -79,14 +79,14 @@ test()
       [&](const cell_iterator &cell) {
         DT                 value = map[cell->id()];
         std::ostringstream oss;
-        oss << "pack " << cell->id() << " " << value;
+        oss << "pack " << cell->id() << ' ' << value;
         input.insert(oss.str());
 
         return value;
       },
       [&](const cell_iterator &cell, const DT &data) {
         std::ostringstream oss;
-        oss << "unpack " << cell->id() << " " << data << " from "
+        oss << "unpack " << cell->id() << ' ' << data << " from "
             << cell->subdomain_id();
 
         output.insert(oss.str());
diff --git a/tests/distributed_grids/grid_tools_exchange_cell_data_02.cc b/tests/distributed_grids/grid_tools_exchange_cell_data_02.cc
index edadccd4e9..e21fe45112 100644
--- a/tests/distributed_grids/grid_tools_exchange_cell_data_02.cc
+++ b/tests/distributed_grids/grid_tools_exchange_cell_data_02.cc
@@ -85,14 +85,14 @@ test()
     [&](const cell_iterator &cell) {
       DT                 value = map[cell->id()];
       std::ostringstream oss;
-      oss << "pack " << cell->id() << " " << value;
+      oss << "pack " << cell->id() << ' ' << value;
       input.insert(oss.str());
 
       return value;
     },
     [&](const cell_iterator &cell, const DT &data) {
       std::ostringstream oss;
-      oss << "unpack " << cell->id() << " " << data << " from "
+      oss << "unpack " << cell->id() << ' ' << data << " from "
           << cell->subdomain_id();
 
       output.insert(oss.str());
diff --git a/tests/distributed_grids/grid_tools_exchange_cell_data_03.cc b/tests/distributed_grids/grid_tools_exchange_cell_data_03.cc
index 837baab774..2f1ec9734f 100644
--- a/tests/distributed_grids/grid_tools_exchange_cell_data_03.cc
+++ b/tests/distributed_grids/grid_tools_exchange_cell_data_03.cc
@@ -84,14 +84,14 @@ test()
     [&](const cell_iterator &cell) {
       DT                 value = map[cell->id()];
       std::ostringstream oss;
-      oss << "pack " << cell->id() << " " << value;
+      oss << "pack " << cell->id() << ' ' << value;
       input.insert(oss.str());
 
       return value;
     },
     [&](const cell_iterator &cell, const DT &data) {
       std::ostringstream oss;
-      oss << "unpack " << cell->id() << " " << data << " from "
+      oss << "unpack " << cell->id() << ' ' << data << " from "
           << cell->subdomain_id();
 
       output.insert(oss.str());
diff --git a/tests/distributed_grids/grid_tools_exchange_cell_data_04.cc b/tests/distributed_grids/grid_tools_exchange_cell_data_04.cc
index 14474c2ed8..7a51fbe0e8 100644
--- a/tests/distributed_grids/grid_tools_exchange_cell_data_04.cc
+++ b/tests/distributed_grids/grid_tools_exchange_cell_data_04.cc
@@ -87,7 +87,7 @@ test()
           {
             DT value = counter;
 
-            oss << "pack " << cell->id() << " " << value;
+            oss << "pack " << cell->id() << ' ' << value;
             input[cell->id()] = oss.str();
             return value;
           }
@@ -100,7 +100,7 @@ test()
       },
       [&](const cell_iterator &cell, const DT &data) {
         std::ostringstream oss;
-        oss << "unpack " << cell->id() << " " << data << " from "
+        oss << "unpack " << cell->id() << ' ' << data << " from "
             << cell->subdomain_id();
 
         output.insert(oss.str());
diff --git a/tests/distributed_grids/hp_2d_dofhandler_01.cc b/tests/distributed_grids/hp_2d_dofhandler_01.cc
index 63815bd95e..e9c4bc73f0 100644
--- a/tests/distributed_grids/hp_2d_dofhandler_01.cc
+++ b/tests/distributed_grids/hp_2d_dofhandler_01.cc
@@ -73,7 +73,7 @@ test()
       cell->get_dof_indices(local_dof_indices);
 
       for (unsigned int i = 0; i < dofs_per_cell; ++i)
-        deallog << local_dof_indices[i] << " ";
+        deallog << local_dof_indices[i] << ' ';
 
       deallog << std::endl;
     }
diff --git a/tests/distributed_grids/solution_transfer_04.cc b/tests/distributed_grids/solution_transfer_04.cc
index 628fe527ff..8f36b5c404 100644
--- a/tests/distributed_grids/solution_transfer_04.cc
+++ b/tests/distributed_grids/solution_transfer_04.cc
@@ -95,8 +95,8 @@ test(std::ostream & /*out*/)
 
   deallog << "#dofs:" << dofh.n_dofs() << std::endl;
 
-  deallog << "norm: " << interpolated_solution1.l2_norm() << " "
-          << interpolated_solution2.l2_norm() << " "
+  deallog << "norm: " << interpolated_solution1.l2_norm() << ' '
+          << interpolated_solution2.l2_norm() << ' '
           << interpolated_solution.l2_norm() << std::endl;
 }
 
diff --git a/tests/distributed_grids/subdomain_id_01.cc b/tests/distributed_grids/subdomain_id_01.cc
index a0ee2136b0..a4abf53586 100644
--- a/tests/distributed_grids/subdomain_id_01.cc
+++ b/tests/distributed_grids/subdomain_id_01.cc
@@ -42,7 +42,7 @@ check(TRIA &tr)
 
   for (; cell != endc; ++cell)
     {
-      deallog << cell->level_subdomain_id() << " ";
+      deallog << cell->level_subdomain_id() << ' ';
       try
         {
           deallog << cell->subdomain_id();
diff --git a/tests/dofs/block_list_02.cc b/tests/dofs/block_list_02.cc
index cbc1adb515..f5e4536bbb 100644
--- a/tests/dofs/block_list_02.cc
+++ b/tests/dofs/block_list_02.cc
@@ -38,7 +38,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("inv vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -54,7 +54,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("inv vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -70,7 +70,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("inv vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -86,7 +86,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("inv vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -102,7 +102,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("inv vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -116,7 +116,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
       bl, dof, level, true, true, true, true, false);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -130,7 +130,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
       bl, dof, level, true, true, false, false, false);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -144,7 +144,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
       bl, dof, level, true, false, false, false, false);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -158,7 +158,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
       bl, dof, level, false, true, true, true, false);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -172,7 +172,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
       bl, dof, level, false, false, false, false, false);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
diff --git a/tests/dofs/block_list_05.cc b/tests/dofs/block_list_05.cc
index f71d1ebaba..0b4624a014 100644
--- a/tests/dofs/block_list_05.cc
+++ b/tests/dofs/block_list_05.cc
@@ -76,7 +76,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -95,7 +95,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -114,7 +114,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
@@ -132,7 +132,7 @@ test_block_list(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
     print_patches(bl);
     deallog.push("vertex mapping");
     for (unsigned int i = 0; i < vm.size(); ++i)
-      deallog << " " << vm[i];
+      deallog << ' ' << vm[i];
     deallog << std::endl;
     deallog.pop();
     deallog.pop();
diff --git a/tests/dofs/dof_constraints_01.cc b/tests/dofs/dof_constraints_01.cc
index b7bad06aca..3f64cd382b 100644
--- a/tests/dofs/dof_constraints_01.cc
+++ b/tests/dofs/dof_constraints_01.cc
@@ -41,7 +41,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_02.cc b/tests/dofs/dof_constraints_02.cc
index 2e63e26a2e..903bc9e2e7 100644
--- a/tests/dofs/dof_constraints_02.cc
+++ b/tests/dofs/dof_constraints_02.cc
@@ -39,7 +39,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_03.cc b/tests/dofs/dof_constraints_03.cc
index 4d43ae9b3d..8479fe22d2 100644
--- a/tests/dofs/dof_constraints_03.cc
+++ b/tests/dofs/dof_constraints_03.cc
@@ -44,7 +44,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_04.cc b/tests/dofs/dof_constraints_04.cc
index 847e70d898..b98158029a 100644
--- a/tests/dofs/dof_constraints_04.cc
+++ b/tests/dofs/dof_constraints_04.cc
@@ -42,7 +42,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_05.cc b/tests/dofs/dof_constraints_05.cc
index b543087fae..ac53810023 100644
--- a/tests/dofs/dof_constraints_05.cc
+++ b/tests/dofs/dof_constraints_05.cc
@@ -42,7 +42,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_06.cc b/tests/dofs/dof_constraints_06.cc
index 76a67cfbee..cf1a1ee0dd 100644
--- a/tests/dofs/dof_constraints_06.cc
+++ b/tests/dofs/dof_constraints_06.cc
@@ -40,7 +40,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_07.cc b/tests/dofs/dof_constraints_07.cc
index 3f604add1c..b8460286ae 100644
--- a/tests/dofs/dof_constraints_07.cc
+++ b/tests/dofs/dof_constraints_07.cc
@@ -44,7 +44,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_08.cc b/tests/dofs/dof_constraints_08.cc
index ad7bd200de..7713f7010c 100644
--- a/tests/dofs/dof_constraints_08.cc
+++ b/tests/dofs/dof_constraints_08.cc
@@ -43,7 +43,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_09.cc b/tests/dofs/dof_constraints_09.cc
index 4f17b25af6..7664887830 100644
--- a/tests/dofs/dof_constraints_09.cc
+++ b/tests/dofs/dof_constraints_09.cc
@@ -44,7 +44,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_10.cc b/tests/dofs/dof_constraints_10.cc
index 6cb1164a4d..b5d1ea5647 100644
--- a/tests/dofs/dof_constraints_10.cc
+++ b/tests/dofs/dof_constraints_10.cc
@@ -42,7 +42,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_11.cc b/tests/dofs/dof_constraints_11.cc
index 960c2d20fe..d5dcfcc069 100644
--- a/tests/dofs/dof_constraints_11.cc
+++ b/tests/dofs/dof_constraints_11.cc
@@ -43,7 +43,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_constraints_11_x.cc b/tests/dofs/dof_constraints_11_x.cc
index ce486e72ee..83376d58cf 100644
--- a/tests/dofs/dof_constraints_11_x.cc
+++ b/tests/dofs/dof_constraints_11_x.cc
@@ -41,7 +41,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/dofs/dof_handler_number_cache_02.cc b/tests/dofs/dof_handler_number_cache_02.cc
index 90e14c9f33..35ad534014 100644
--- a/tests/dofs/dof_handler_number_cache_02.cc
+++ b/tests/dofs/dof_handler_number_cache_02.cc
@@ -106,11 +106,11 @@ test()
 
       dof_handler.clear();
       deallog << "those should be zero: " << dof_handler.n_locally_owned_dofs()
-              << " "
+              << ' '
               << Utilities::MPI::all_gather(MPI_COMM_SELF,
                                             dof_handler.n_locally_owned_dofs())
                    .size()
-              << " " << dof_handler.n_dofs() << std::endl;
+              << ' ' << dof_handler.n_dofs() << std::endl;
     }
 }
 
diff --git a/tests/dofs/dof_renumbering_10.cc b/tests/dofs/dof_renumbering_10.cc
index e6d4a59a36..53bf5ac681 100644
--- a/tests/dofs/dof_renumbering_10.cc
+++ b/tests/dofs/dof_renumbering_10.cc
@@ -98,9 +98,9 @@ test(const bool adaptive_ref = true)
   for (const auto &c : cell_order)
     {
       c->get_active_or_mg_dof_indices(cell_dofs);
-      deallog << c->center() << ":";
+      deallog << c->center() << ':';
       for (const auto d : cell_dofs)
-        deallog << " " << d;
+        deallog << ' ' << d;
       deallog << std::endl;
     }
 
@@ -134,14 +134,14 @@ test(const bool adaptive_ref = true)
         << "plot '-' using 1:2 with lines notitle, '-' with labels tc rgb 'red' nopoint notitle, '-' with labels point pt 4 offset 1,1 notitle"
         << std::endl;
       GridOut().write_gnuplot(tria, f);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       // output cell order
       for (unsigned int index = 0; index < cell_order.size(); ++index)
         f << cell_order[index]->center() << " \"" << index << "\"\n";
 
       f << std::flush;
-      f << "e" << std::endl << std::endl;
+      f << 'e' << std::endl << std::endl;
 
       // output only owned support points
       for (auto it = support_points.cbegin(); it != support_points.cend();)
@@ -154,7 +154,7 @@ test(const bool adaptive_ref = true)
 
       DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
 
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
     }
 }
 
diff --git a/tests/dofs/dof_tools_01a.cc b/tests/dofs/dof_tools_01a.cc
index 16614ed1ea..9c670a6ccf 100644
--- a/tests/dofs/dof_tools_01a.cc
+++ b/tests/dofs/dof_tools_01a.cc
@@ -45,7 +45,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 10);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_01a_constraints_false.cc b/tests/dofs/dof_tools_01a_constraints_false.cc
index 857004ef6d..628f3801c7 100644
--- a/tests/dofs/dof_tools_01a_constraints_false.cc
+++ b/tests/dofs/dof_tools_01a_constraints_false.cc
@@ -51,7 +51,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 10);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_01a_constraints_true.cc b/tests/dofs/dof_tools_01a_constraints_true.cc
index e93dc88bd8..ec762dac7f 100644
--- a/tests/dofs/dof_tools_01a_constraints_true.cc
+++ b/tests/dofs/dof_tools_01a_constraints_true.cc
@@ -51,7 +51,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 10);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_01a_subdomain.cc b/tests/dofs/dof_tools_01a_subdomain.cc
index 6dc1feb302..bb9e8c85c4 100644
--- a/tests/dofs/dof_tools_01a_subdomain.cc
+++ b/tests/dofs/dof_tools_01a_subdomain.cc
@@ -51,7 +51,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 10);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_01b.cc b/tests/dofs/dof_tools_01b.cc
index 4979db4b7e..9263c244e5 100644
--- a/tests/dofs/dof_tools_01b.cc
+++ b/tests/dofs/dof_tools_01b.cc
@@ -44,7 +44,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_01c.cc b/tests/dofs/dof_tools_01c.cc
index 1a3e7ba00d..7fb2cd3c33 100644
--- a/tests/dofs/dof_tools_01c.cc
+++ b/tests/dofs/dof_tools_01c.cc
@@ -71,7 +71,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_01d.cc b/tests/dofs/dof_tools_01d.cc
index f2530e02f4..ee783c58a4 100644
--- a/tests/dofs/dof_tools_01d.cc
+++ b/tests/dofs/dof_tools_01d.cc
@@ -69,7 +69,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_02a.cc b/tests/dofs/dof_tools_02a.cc
index e2a08acd77..022b13b501 100644
--- a/tests/dofs/dof_tools_02a.cc
+++ b/tests/dofs/dof_tools_02a.cc
@@ -55,7 +55,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_02a_constraints_false.cc b/tests/dofs/dof_tools_02a_constraints_false.cc
index ab66069690..a8d3a3f853 100644
--- a/tests/dofs/dof_tools_02a_constraints_false.cc
+++ b/tests/dofs/dof_tools_02a_constraints_false.cc
@@ -61,7 +61,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 10);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_02a_constraints_true.cc b/tests/dofs/dof_tools_02a_constraints_true.cc
index ce60161bc2..d0558996c4 100644
--- a/tests/dofs/dof_tools_02a_constraints_true.cc
+++ b/tests/dofs/dof_tools_02a_constraints_true.cc
@@ -61,7 +61,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 10);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_02a_subdomain.cc b/tests/dofs/dof_tools_02a_subdomain.cc
index 1b229e30d5..705476ecee 100644
--- a/tests/dofs/dof_tools_02a_subdomain.cc
+++ b/tests/dofs/dof_tools_02a_subdomain.cc
@@ -62,7 +62,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 10);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_02b.cc b/tests/dofs/dof_tools_02b.cc
index de10e91ee6..a05d439c91 100644
--- a/tests/dofs/dof_tools_02b.cc
+++ b/tests/dofs/dof_tools_02b.cc
@@ -54,7 +54,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_02c.cc b/tests/dofs/dof_tools_02c.cc
index aa02382bd5..9293df03b9 100644
--- a/tests/dofs/dof_tools_02c.cc
+++ b/tests/dofs/dof_tools_02c.cc
@@ -80,7 +80,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_02d.cc b/tests/dofs/dof_tools_02d.cc
index 36fd531fa4..6dd583f7d1 100644
--- a/tests/dofs/dof_tools_02d.cc
+++ b/tests/dofs/dof_tools_02d.cc
@@ -78,7 +78,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_07.cc b/tests/dofs/dof_tools_07.cc
index ff0b36a5da..ad65e90904 100644
--- a/tests/dofs/dof_tools_07.cc
+++ b/tests/dofs/dof_tools_07.cc
@@ -30,6 +30,6 @@ check_this(const DoFHandler<dim> &dof_handler)
   const std::vector<types::global_dof_index> n_dofs =
     DoFTools::count_dofs_per_fe_component(dof_handler);
   for (unsigned int i = 0; i < n_dofs.size(); ++i)
-    deallog << n_dofs[i] << " ";
+    deallog << n_dofs[i] << ' ';
   deallog << std::endl;
 }
diff --git a/tests/dofs/dof_tools_08.cc b/tests/dofs/dof_tools_08.cc
index 33a73ed18b..2d31a1346c 100644
--- a/tests/dofs/dof_tools_08.cc
+++ b/tests/dofs/dof_tools_08.cc
@@ -31,6 +31,6 @@ check_this(const DoFHandler<dim> &dof_handler)
   std::vector<types::global_dof_index> map(dof_handler.n_dofs());
   DoFTools::map_dof_to_boundary_indices(dof_handler, map);
   for (unsigned int i = 0; i < map.size(); ++i)
-    deallog << (int)map[i] << " ";
+    deallog << (int)map[i] << ' ';
   deallog << std::endl;
 }
diff --git a/tests/dofs/dof_tools_09.cc b/tests/dofs/dof_tools_09.cc
index 72951106fa..4584d6ce56 100644
--- a/tests/dofs/dof_tools_09.cc
+++ b/tests/dofs/dof_tools_09.cc
@@ -39,7 +39,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     deallog << (map[i] == numbers::invalid_dof_index ?
                   -1 :
                   static_cast<signed int>(map[i]))
-            << " ";
+            << ' ';
   deallog << std::endl;
 
   // check for boundary id 0 and 1
@@ -49,6 +49,6 @@ check_this(const DoFHandler<dim> &dof_handler)
     deallog << (map[i] == numbers::invalid_dof_index ?
                   -1 :
                   static_cast<signed int>(map[i]))
-            << " ";
+            << ' ';
   deallog << std::endl;
 }
diff --git a/tests/dofs/dof_tools_10.cc b/tests/dofs/dof_tools_10.cc
index da251762af..592f6d5f84 100644
--- a/tests/dofs/dof_tools_10.cc
+++ b/tests/dofs/dof_tools_10.cc
@@ -43,6 +43,6 @@ check_this(const DoFHandler<dim> &dof_handler)
 
   // output every third element
   for (unsigned int i = 0; i < map.size(); i += 3)
-    deallog << map[i] << " ";
+    deallog << map[i] << ' ';
   deallog << std::endl;
 }
diff --git a/tests/dofs/dof_tools_13.cc b/tests/dofs/dof_tools_13.cc
index b26f2a8cc3..5cd4597990 100644
--- a/tests/dofs/dof_tools_13.cc
+++ b/tests/dofs/dof_tools_13.cc
@@ -44,7 +44,7 @@ check_this(const DoFHandler<dim> &dof_handler)
 
   // output every third element
   for (unsigned int i = 0; i < dof_data.size(); i += 3)
-    deallog << dof_data(i) << " ";
+    deallog << dof_data(i) << ' ';
   deallog << std::endl;
 
 
@@ -54,6 +54,6 @@ check_this(const DoFHandler<dim> &dof_handler)
   DoFTools::distribute_cell_to_dof_vector(
     dof_handler, cell_data, dof_data, dof_handler.get_fe().n_components() - 1);
   for (unsigned int i = 0; i < dof_data.size(); i += 3)
-    deallog << dof_data(i) << " ";
+    deallog << dof_data(i) << ' ';
   deallog << std::endl;
 }
diff --git a/tests/dofs/dof_tools_13a.cc b/tests/dofs/dof_tools_13a.cc
index 70798a048c..712d551328 100644
--- a/tests/dofs/dof_tools_13a.cc
+++ b/tests/dofs/dof_tools_13a.cc
@@ -65,7 +65,7 @@ check_this(const DoFHandler<dim> &dof_handler)
   DoFTools::distribute_cell_to_dof_vector(dof_handler, cell_data, dof_data);
   // output every third element
   for (unsigned int i = 0; i < dof_data.size(); i += 3)
-    deallog << dof_data(i) << " ";
+    deallog << dof_data(i) << ' ';
   deallog << std::endl;
 
   // check that no other values were
@@ -97,7 +97,7 @@ check_this(const DoFHandler<dim> &dof_handler)
   DoFTools::distribute_cell_to_dof_vector(
     dof_handler, cell_data, dof_data, dof_handler.get_fe().n_components() - 1);
   for (unsigned int i = 0; i < dof_data.size(); i += 3)
-    deallog << dof_data(i) << " ";
+    deallog << dof_data(i) << ' ';
   deallog << std::endl;
 
   // check that no other values were
diff --git a/tests/dofs/dof_tools_15a.cc b/tests/dofs/dof_tools_15a.cc
index aba0ebe1f0..72ef1c6ec7 100644
--- a/tests/dofs/dof_tools_15a.cc
+++ b/tests/dofs/dof_tools_15a.cc
@@ -54,7 +54,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_15b.cc b/tests/dofs/dof_tools_15b.cc
index 3b815d127e..d8ea8b22f1 100644
--- a/tests/dofs/dof_tools_15b.cc
+++ b/tests/dofs/dof_tools_15b.cc
@@ -53,7 +53,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_15c.cc b/tests/dofs/dof_tools_15c.cc
index c69903bba2..a97f552f57 100644
--- a/tests/dofs/dof_tools_15c.cc
+++ b/tests/dofs/dof_tools_15c.cc
@@ -79,7 +79,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_15d.cc b/tests/dofs/dof_tools_15d.cc
index 0350ffa1b1..0d4db856b4 100644
--- a/tests/dofs/dof_tools_15d.cc
+++ b/tests/dofs/dof_tools_15d.cc
@@ -77,7 +77,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_16a.cc b/tests/dofs/dof_tools_16a.cc
index 2ba9c03f4f..a52746d08e 100644
--- a/tests/dofs/dof_tools_16a.cc
+++ b/tests/dofs/dof_tools_16a.cc
@@ -60,7 +60,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_16b.cc b/tests/dofs/dof_tools_16b.cc
index 93be77c95f..ecb636819a 100644
--- a/tests/dofs/dof_tools_16b.cc
+++ b/tests/dofs/dof_tools_16b.cc
@@ -59,7 +59,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_16c.cc b/tests/dofs/dof_tools_16c.cc
index 5b988e1ed2..1c910ac0bc 100644
--- a/tests/dofs/dof_tools_16c.cc
+++ b/tests/dofs/dof_tools_16c.cc
@@ -85,7 +85,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_16d.cc b/tests/dofs/dof_tools_16d.cc
index 484ac3e0b6..be209e065d 100644
--- a/tests/dofs/dof_tools_16d.cc
+++ b/tests/dofs/dof_tools_16d.cc
@@ -84,7 +84,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_17a.cc b/tests/dofs/dof_tools_17a.cc
index 6dccceb50c..ed465fcb31 100644
--- a/tests/dofs/dof_tools_17a.cc
+++ b/tests/dofs/dof_tools_17a.cc
@@ -45,7 +45,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_17b.cc b/tests/dofs/dof_tools_17b.cc
index 6642920924..b8a57b0099 100644
--- a/tests/dofs/dof_tools_17b.cc
+++ b/tests/dofs/dof_tools_17b.cc
@@ -44,7 +44,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_17c.cc b/tests/dofs/dof_tools_17c.cc
index 4fe3bf8a88..0e1d522b1b 100644
--- a/tests/dofs/dof_tools_17c.cc
+++ b/tests/dofs/dof_tools_17c.cc
@@ -71,7 +71,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_17d.cc b/tests/dofs/dof_tools_17d.cc
index 599f1cbca7..2b642ae85f 100644
--- a/tests/dofs/dof_tools_17d.cc
+++ b/tests/dofs/dof_tools_17d.cc
@@ -69,7 +69,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_18a.cc b/tests/dofs/dof_tools_18a.cc
index 22e96c2df6..3fa6f2ef15 100644
--- a/tests/dofs/dof_tools_18a.cc
+++ b/tests/dofs/dof_tools_18a.cc
@@ -66,7 +66,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_18a_1d.cc b/tests/dofs/dof_tools_18a_1d.cc
index 5c60786732..002fadd357 100644
--- a/tests/dofs/dof_tools_18a_1d.cc
+++ b/tests/dofs/dof_tools_18a_1d.cc
@@ -71,7 +71,7 @@ check_this(const DoFHandler<dim> &dof_handler)
   for (unsigned int l = 0; l < sp.n_rows(); ++l)
     {
       for (unsigned int c = 0; c < sp.row_length(l); ++c)
-        deallog << sp.column_number(l, c) << " ";
+        deallog << sp.column_number(l, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_18b.cc b/tests/dofs/dof_tools_18b.cc
index 7470445df0..ea73598cff 100644
--- a/tests/dofs/dof_tools_18b.cc
+++ b/tests/dofs/dof_tools_18b.cc
@@ -65,7 +65,7 @@ check_this(const DoFHandler<dim> &dof_handler)
     {
       const unsigned int line = l * (sp.n_rows() / 20);
       for (unsigned int c = 0; c < sp.row_length(line); ++c)
-        deallog << sp.column_number(line, c) << " ";
+        deallog << sp.column_number(line, c) << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/dofs/dof_tools_18c.cc b/tests/dofs/dof_tools_18c.cc
index 23fbca8376..bf4077a21f 100644
--- a/tests/dofs/dof_tools_18c.cc
+++ b/tests/dofs/dof_tools_18c.cc
@@ -92,7 +92,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_18d.cc b/tests/dofs/dof_tools_18d.cc
index f55e6ce3c8..bb14ae711b 100644
--- a/tests/dofs/dof_tools_18d.cc
+++ b/tests/dofs/dof_tools_18d.cc
@@ -90,7 +90,7 @@ check_this(const DoFHandler<dim> &dof_handler)
                ++c)
             deallog << sp.block(block_row.first, col)
                          .column_number(block_row.second, c)
-                    << " ";
+                    << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/dofs/dof_tools_21_b.cc b/tests/dofs/dof_tools_21_b.cc
index 3593fee820..a11e9b08fb 100644
--- a/tests/dofs/dof_tools_21_b.cc
+++ b/tests/dofs/dof_tools_21_b.cc
@@ -297,24 +297,24 @@ print_matching(DoFHandler<dim, spacedim> &dof_handler,
   deallog << "DoFs of face_1:";
   for (unsigned int c = 0; c < fe.n_components(); ++c)
     {
-      deallog << std::endl << " component " << c << ":";
+      deallog << std::endl << " component " << c << ':';
       for (unsigned int i = 0; i < fe.dofs_per_face; ++i)
         {
           if (fe.face_system_to_component_index(i).first == c)
             deallog << " (" << dofs_1[i] << " - " << support_points[dofs_1[i]]
-                    << ")";
+                    << ')';
         }
     }
   deallog << std::endl;
   deallog << "DoFs of face_2:";
   for (unsigned int c = 0; c < fe.n_components(); ++c)
     {
-      deallog << std::endl << " component " << c << ":";
+      deallog << std::endl << " component " << c << ':';
       for (unsigned int i = 0; i < fe.dofs_per_face; ++i)
         {
           if (fe.face_system_to_component_index(i).first == c)
             deallog << " (" << dofs_2[i] << " - " << support_points[dofs_2[i]]
-                    << ")";
+                    << ')';
         }
     }
   deallog << std::endl;
diff --git a/tests/dofs/dof_tools_21_c.cc b/tests/dofs/dof_tools_21_c.cc
index fad55f205f..7b0a7292ce 100644
--- a/tests/dofs/dof_tools_21_c.cc
+++ b/tests/dofs/dof_tools_21_c.cc
@@ -303,24 +303,24 @@ print_matching(DoFHandler<dim, spacedim> &dof_handler,
   deallog << "DoFs of face_1:";
   for (unsigned int c = 0; c < fe.n_components(); ++c)
     {
-      deallog << std::endl << " component " << c << ":";
+      deallog << std::endl << " component " << c << ':';
       for (unsigned int i = 0; i < fe.dofs_per_face; ++i)
         {
           if (fe.face_system_to_component_index(i).first == c)
             deallog << " (" << dofs_1[i] << " - " << support_points[dofs_1[i]]
-                    << ")";
+                    << ')';
         }
     }
   deallog << std::endl;
   deallog << "DoFs of face_2:";
   for (unsigned int c = 0; c < fe.n_components(); ++c)
     {
-      deallog << std::endl << " component " << c << ":";
+      deallog << std::endl << " component " << c << ':';
       for (unsigned int i = 0; i < fe.dofs_per_face; ++i)
         {
           if (fe.face_system_to_component_index(i).first == c)
             deallog << " (" << dofs_2[i] << " - " << support_points[dofs_2[i]]
-                    << ")";
+                    << ')';
         }
     }
   deallog << std::endl;
diff --git a/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_01.cc b/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_01.cc
index d35bfa0c45..f970c2b1a6 100644
--- a/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_01.cc
+++ b/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_01.cc
@@ -110,10 +110,10 @@ test(const unsigned int flag)
         << "plot '-' using 1:2 with lines notitle, '-' with labels point pt 2 offset 1,1 notitle"
         << std::endl;
       GridOut().write_gnuplot(triangulation, f);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
     }
 
   dh.clear();
diff --git a/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_03.cc b/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_03.cc
index fec497e793..7487ffa228 100644
--- a/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_03.cc
+++ b/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_03.cc
@@ -135,10 +135,10 @@ test(const bool left = true)
         << "plot '-' using 1:2 with lines notitle, '-' with labels point pt 2 offset 1,1 notitle"
         << std::endl;
       GridOut().write_gnuplot(triangulation, f);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
     }
 
   dh.clear();
diff --git a/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_04.cc b/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_04.cc
index 5d26d2554b..03dc03acf0 100644
--- a/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_04.cc
+++ b/tests/dofs/dof_tools_extract_dofs_with_support_contained_within_04.cc
@@ -241,10 +241,10 @@ test()
           << "plot '-' using 1:2 with lines notitle, '-' with labels point pt 2 offset 1,1 notitle"
           << std::endl;
         GridOut().write_gnuplot(triangulation, f);
-        f << "e" << std::endl;
+        f << 'e' << std::endl;
 
         DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
-        f << "e" << std::endl;
+        f << 'e' << std::endl;
       }
 
       {
diff --git a/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_01.cc b/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_01.cc
index b956283bd1..d7e41f65d1 100644
--- a/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_01.cc
+++ b/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_01.cc
@@ -56,7 +56,7 @@ test()
   out << "plot '-' using 1:2 with lines, '-' with labels point pt 2 offset 1,1"
       << std::endl;
   GridOut().write_gnuplot(triangulation, deallog.get_file_stream());
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 
   std::map<types::global_dof_index, Point<dim>> support_points;
   DoFTools::map_dofs_to_support_points(MappingQ1<dim>(),
@@ -64,7 +64,7 @@ test()
                                        support_points);
   DoFTools::write_gnuplot_dof_support_point_info(deallog.get_file_stream(),
                                                  support_points);
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 }
 
 
diff --git a/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_02.cc b/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_02.cc
index 869581f764..3bfa891200 100644
--- a/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_02.cc
+++ b/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_02.cc
@@ -61,11 +61,11 @@ test()
       << "plot '-' using 1:2 with lines, '-' with labels point pt 2 offset 1,1"
       << std::endl;
   GridOut().write_gnuplot(triangulation, deallog.get_file_stream());
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 
   DoFTools::write_gnuplot_dof_support_point_info(deallog.get_file_stream(),
                                                  support_points);
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 }
 
 
diff --git a/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_03.cc b/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_03.cc
index 1c95e64123..da587ecdc8 100644
--- a/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_03.cc
+++ b/tests/dofs/dof_tools_write_gnuplot_dof_support_point_info_03.cc
@@ -62,11 +62,11 @@ test()
       << "plot '-' using 1:2 with lines, '-' with labels point pt 2 offset 1,1"
       << std::endl;
   GridOut().write_gnuplot(triangulation, deallog.get_file_stream());
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 
   DoFTools::write_gnuplot_dof_support_point_info(deallog.get_file_stream(),
                                                  support_points);
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 }
 
 
diff --git a/tests/dofs/interpolate_boundary_values_01.cc b/tests/dofs/interpolate_boundary_values_01.cc
index b08951f0f1..572c5bc950 100644
--- a/tests/dofs/interpolate_boundary_values_01.cc
+++ b/tests/dofs/interpolate_boundary_values_01.cc
@@ -191,7 +191,7 @@ FindBug<dim>::dirichlet_conditions()
                                            component_mask);
   for (unsigned int i = 0; i < dof_handler.n_dofs(); ++i)
     if (fixed_dofs[i] == true)
-      deallog << i << " " << dirichlet_dofs[i] << std::endl;
+      deallog << i << ' ' << dirichlet_dofs[i] << std::endl;
 }
 
 
diff --git a/tests/dofs/map_dofs_to_support_points_01.cc b/tests/dofs/map_dofs_to_support_points_01.cc
index fd72e9c435..0ae480dd91 100644
--- a/tests/dofs/map_dofs_to_support_points_01.cc
+++ b/tests/dofs/map_dofs_to_support_points_01.cc
@@ -69,7 +69,7 @@ test()
 
   for (; it_0 != support_points_0.end(); ++it_0, ++it_1)
     {
-      deallog << it_0->second << " " << it_1->second << std::endl;
+      deallog << it_0->second << ' ' << it_1->second << std::endl;
     }
 }
 
diff --git a/tests/fail/hp-step-14.cc b/tests/fail/hp-step-14.cc
index 7f349cfd3d..676bec0945 100644
--- a/tests/fail/hp-step-14.cc
+++ b/tests/fail/hp-step-14.cc
@@ -256,7 +256,7 @@ namespace Evaluation
                               const Vector<double> & /*solution*/) const
   {
     std::ostringstream filename;
-    filename << output_name_base << "-" << this->refinement_cycle << ".eps"
+    filename << output_name_base << '-' << this->refinement_cycle << ".eps"
              << std::ends;
 
     GridOut().write_eps(dof_handler.get_triangulation(),
diff --git a/tests/fail/hp-step-15.cc b/tests/fail/hp-step-15.cc
index 85cafd7796..3270cc851c 100644
--- a/tests/fail/hp-step-15.cc
+++ b/tests/fail/hp-step-15.cc
@@ -611,7 +611,7 @@ main()
       for (unsigned int realization = 0; realization < n_realizations;
            ++realization)
         {
-          deallog << "Realization " << realization << ":" << std::endl;
+          deallog << "Realization " << realization << ':' << std::endl;
 
           MinimizationProblem<1> minimization_problem_1d(realization);
           minimization_problem_1d.run();
diff --git a/tests/fail/rt_4.cc b/tests/fail/rt_4.cc
index 56caa4282d..797f6fa5c4 100644
--- a/tests/fail/rt_4.cc
+++ b/tests/fail/rt_4.cc
@@ -31,7 +31,7 @@ template <int dim>
 void
 test(const unsigned int degree)
 {
-  deallog << "FE_RaviartThomas<" << dim << "> (" << degree << ")" << std::endl;
+  deallog << "FE_RaviartThomas<" << dim << "> (" << degree << ')' << std::endl;
 
   FE_RaviartThomas<dim> fe_rt(degree);
 
diff --git a/tests/fail/rt_6.cc b/tests/fail/rt_6.cc
index 6db8ad537e..a900a4a9b8 100644
--- a/tests/fail/rt_6.cc
+++ b/tests/fail/rt_6.cc
@@ -121,7 +121,7 @@ check_element(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
   const double threshold = 1e-6;
   deallog << ", dofs_per_cell=" << fe.dofs_per_cell << "; relative residual: "
           << (relative_residual < threshold ? "ok" : "botched up!")
-          << " (relative residual=" << relative_residual << ")" << std::endl;
+          << " (relative residual=" << relative_residual << ')' << std::endl;
 }
 
 
diff --git a/tests/fail/scalapack_15_b.cc b/tests/fail/scalapack_15_b.cc
index 11cda0ccd8..c4a3797311 100644
--- a/tests/fail/scalapack_15_b.cc
+++ b/tests/fail/scalapack_15_b.cc
@@ -56,8 +56,8 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   const unsigned int n_eigenvalues     = size;
   const unsigned int max_n_eigenvalues = 5;
diff --git a/tests/fail/step-15.cc b/tests/fail/step-15.cc
index a7f044647f..f503a3cba2 100644
--- a/tests/fail/step-15.cc
+++ b/tests/fail/step-15.cc
@@ -589,7 +589,7 @@ main()
       for (unsigned int realization = 0; realization < n_realizations;
            ++realization)
         {
-          deallog << "Realization " << realization << ":" << std::endl;
+          deallog << "Realization " << realization << ':' << std::endl;
 
           MinimizationProblem<1> minimization_problem_1d(realization);
           minimization_problem_1d.run();
diff --git a/tests/fe/bdm_1.cc b/tests/fe/bdm_1.cc
index adedfeb414..da7706d712 100644
--- a/tests/fe/bdm_1.cc
+++ b/tests/fe/bdm_1.cc
@@ -57,7 +57,7 @@ plot_shape_functions(const unsigned int degree)
             for (unsigned int i = 0; i < fe_bdm.dofs_per_cell; ++i)
               {
                 for (unsigned int c = 0; c < dim; ++c)
-                  deallog << " " << fe_bdm.shape_value_component(i, p, c);
+                  deallog << ' ' << fe_bdm.shape_value_component(i, p, c);
                 deallog << "  ";
               }
             deallog << std::endl << "grad " << p;
diff --git a/tests/fe/bdm_16.cc b/tests/fe/bdm_16.cc
index 970b5404d9..32f14ff76e 100644
--- a/tests/fe/bdm_16.cc
+++ b/tests/fe/bdm_16.cc
@@ -42,7 +42,7 @@ test(const unsigned int degree)
           << ", restriction is additive flags:" << std::endl;
 
   for (unsigned int i = 0; i < fe_bdm.dofs_per_cell; ++i)
-    deallog << fe_bdm.restriction_is_additive(i) << " ";
+    deallog << fe_bdm.restriction_is_additive(i) << ' ';
 
   deallog << std::endl;
 }
diff --git a/tests/fe/bdm_3.cc b/tests/fe/bdm_3.cc
index 2b54e84fc3..cde712ae53 100644
--- a/tests/fe/bdm_3.cc
+++ b/tests/fe/bdm_3.cc
@@ -31,7 +31,7 @@ template <int dim>
 void
 test(const unsigned int degree)
 {
-  deallog << "FE_BDM<" << dim << "> (" << degree << ")" << std::endl;
+  deallog << "FE_BDM<" << dim << "> (" << degree << ')' << std::endl;
 
   FE_BDM<dim>               fe_rt(degree);
   const FullMatrix<double> &constraints = fe_rt.constraints();
diff --git a/tests/fe/bdm_5.cc b/tests/fe/bdm_5.cc
index 59d516f3a8..7b79b875ab 100644
--- a/tests/fe/bdm_5.cc
+++ b/tests/fe/bdm_5.cc
@@ -31,7 +31,7 @@ template <int dim>
 void
 test(const unsigned int degree)
 {
-  deallog << "FE_BDM<" << dim << "> (" << degree << ")" << std::endl;
+  deallog << "FE_BDM<" << dim << "> (" << degree << ')' << std::endl;
 
   FE_BDM<dim> fe_rt(degree);
 
diff --git a/tests/fe/cell_similarity_11.cc b/tests/fe/cell_similarity_11.cc
index 08ec1326e7..0080b0f4ba 100644
--- a/tests/fe/cell_similarity_11.cc
+++ b/tests/fe/cell_similarity_11.cc
@@ -83,7 +83,7 @@ test(const Triangulation<dim> &tr)
           deallog << "[ ";
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
-              deallog << fe_values.jacobian(q)[d][e] << " ";
+              deallog << fe_values.jacobian(q)[d][e] << ' ';
           deallog << " ] ";
         }
       deallog << std::endl;
@@ -92,7 +92,7 @@ test(const Triangulation<dim> &tr)
         {
           deallog << "[ ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << fe_values.shape_grad(fe.dofs_per_cell / 2, q)[d] << " ";
+            deallog << fe_values.shape_grad(fe.dofs_per_cell / 2, q)[d] << ' ';
           deallog << " ] ";
         }
       deallog << std::endl;
diff --git a/tests/fe/cell_similarity_12.cc b/tests/fe/cell_similarity_12.cc
index 1135bdf409..7d4757d309 100644
--- a/tests/fe/cell_similarity_12.cc
+++ b/tests/fe/cell_similarity_12.cc
@@ -84,7 +84,7 @@ test(const unsigned int degree)
             deallog << "[ ";
             for (unsigned int d = 0; d < dim; ++d)
               for (unsigned int e = 0; e < dim; ++e)
-                deallog << fe_values.jacobian(q)[d][e] << " ";
+                deallog << fe_values.jacobian(q)[d][e] << ' ';
             deallog << " ] ";
           }
         deallog << std::endl;
@@ -94,7 +94,7 @@ test(const unsigned int degree)
             deallog << "[ ";
             for (unsigned int d = 0; d < dim; ++d)
               deallog << fe_values.shape_grad(fe.dofs_per_cell / 2, q)[d]
-                      << " ";
+                      << ' ';
             deallog << " ] ";
           }
         deallog << std::endl;
diff --git a/tests/fe/cell_similarity_13.cc b/tests/fe/cell_similarity_13.cc
index 1312451d01..8d9eab21b7 100644
--- a/tests/fe/cell_similarity_13.cc
+++ b/tests/fe/cell_similarity_13.cc
@@ -77,7 +77,7 @@ test()
           deallog << "[ ";
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
-              deallog << fe_values.jacobian(q)[d][e] << " ";
+              deallog << fe_values.jacobian(q)[d][e] << ' ';
           deallog << " ] ";
         }
       deallog << std::endl;
@@ -86,7 +86,7 @@ test()
         {
           deallog << "[ ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << fe_values.shape_grad(fe.dofs_per_cell / 2, q)[d] << " ";
+            deallog << fe_values.shape_grad(fe.dofs_per_cell / 2, q)[d] << ' ';
           deallog << " ] ";
         }
       deallog << std::endl;
diff --git a/tests/fe/copy_01.cc b/tests/fe/copy_01.cc
index ff1875cdca..8a24f41c02 100644
--- a/tests/fe/copy_01.cc
+++ b/tests/fe/copy_01.cc
@@ -34,7 +34,7 @@ template <int dim>
 void
 test(const unsigned int degree)
 {
-  deallog << "FE_Q<" << dim << "> (" << degree << ")" << std::endl;
+  deallog << "FE_Q<" << dim << "> (" << degree << ')' << std::endl;
 
   FE_Q<dim> fe_q(degree);
   FE_Q<dim> x(fe_q);
diff --git a/tests/fe/dgp_monomial_1.cc b/tests/fe/dgp_monomial_1.cc
index 3c5a3f9ee8..21d726ab5a 100644
--- a/tests/fe/dgp_monomial_1.cc
+++ b/tests/fe/dgp_monomial_1.cc
@@ -34,7 +34,7 @@ template <int dim>
 void
 test(const unsigned int degree)
 {
-  deallog << "FE_DGPMonomial<" << dim << "> (" << degree << ")" << std::endl;
+  deallog << "FE_DGPMonomial<" << dim << "> (" << degree << ')' << std::endl;
 
   FE_DGPMonomial<dim> fe_q(degree);
 
diff --git a/tests/fe/dgp_monomial_2.cc b/tests/fe/dgp_monomial_2.cc
index f671ae1400..54ba0735b4 100644
--- a/tests/fe/dgp_monomial_2.cc
+++ b/tests/fe/dgp_monomial_2.cc
@@ -35,8 +35,8 @@ template <int dim>
 void
 test(const unsigned int degree1, const unsigned int degree2)
 {
-  deallog << "FE_DGPMonomial" << dim << "> (" << degree1 << ")"
-          << " to FE_DGPMonomial<" << dim << "> (" << degree2 << ")"
+  deallog << "FE_DGPMonomial" << dim << "> (" << degree1 << ')'
+          << " to FE_DGPMonomial<" << dim << "> (" << degree2 << ')'
           << std::endl;
 
   FE_DGPMonomial<dim> fe1(degree1);
diff --git a/tests/fe/dgq_1.cc b/tests/fe/dgq_1.cc
index 873fe53baa..6272b5d567 100644
--- a/tests/fe/dgq_1.cc
+++ b/tests/fe/dgq_1.cc
@@ -35,8 +35,8 @@ template <int dim>
 void
 test(const unsigned int degree1, const unsigned int degree2)
 {
-  deallog << "FE_DGQ<" << dim << "> (" << degree1 << ")"
-          << " to FE_DGQ<" << dim << "> (" << degree2 << ")" << std::endl;
+  deallog << "FE_DGQ<" << dim << "> (" << degree1 << ')' << " to FE_DGQ<" << dim
+          << "> (" << degree2 << ')' << std::endl;
 
   FE_DGQ<dim> fe1(degree1);
   FE_DGQ<dim> fe2(degree2);
diff --git a/tests/fe/element_constant_modes.cc b/tests/fe/element_constant_modes.cc
index 1acfeb144c..ad0c50482f 100644
--- a/tests/fe/element_constant_modes.cc
+++ b/tests/fe/element_constant_modes.cc
@@ -38,7 +38,7 @@ print_constant_modes(const FiniteElement<dim> &fe)
   for (unsigned int r = 0; r < constant_modes.n_rows(); ++r)
     {
       for (unsigned int c = 0; c < constant_modes.n_cols(); ++c)
-        deallog << constant_modes(r, c) << " ";
+        deallog << constant_modes(r, c) << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/fe/fe_abf_gradient_divergence_theorem.cc b/tests/fe/fe_abf_gradient_divergence_theorem.cc
index 5dafb8e852..09f8e15f89 100644
--- a/tests/fe/fe_abf_gradient_divergence_theorem.cc
+++ b/tests/fe/fe_abf_gradient_divergence_theorem.cc
@@ -89,8 +89,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_br.cc b/tests/fe/fe_br.cc
index 6e26b0a0fa..6a7816ee13 100644
--- a/tests/fe/fe_br.cc
+++ b/tests/fe/fe_br.cc
@@ -80,8 +80,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       for (unsigned int c = 0; c < fe.n_components(); ++c)
diff --git a/tests/fe/fe_dgp_3rd_derivative_divergence_theorem.cc b/tests/fe/fe_dgp_3rd_derivative_divergence_theorem.cc
index 4b3d6706a4..1907c7da9d 100644
--- a/tests/fe/fe_dgp_3rd_derivative_divergence_theorem.cc
+++ b/tests/fe/fe_dgp_3rd_derivative_divergence_theorem.cc
@@ -87,8 +87,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_dgq_3rd_derivative_divergence_theorem.cc b/tests/fe/fe_dgq_3rd_derivative_divergence_theorem.cc
index 9bd96014a4..2ab4a615fe 100644
--- a/tests/fe/fe_dgq_3rd_derivative_divergence_theorem.cc
+++ b/tests/fe/fe_dgq_3rd_derivative_divergence_theorem.cc
@@ -86,8 +86,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_dgq_gradient_divergence_theorem.cc b/tests/fe/fe_dgq_gradient_divergence_theorem.cc
index be8fb43266..122ccf2a3d 100644
--- a/tests/fe/fe_dgq_gradient_divergence_theorem.cc
+++ b/tests/fe/fe_dgq_gradient_divergence_theorem.cc
@@ -88,8 +88,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_dgq_hessian_divergence_theorem.cc b/tests/fe/fe_dgq_hessian_divergence_theorem.cc
index 7dcdaac230..af8632d946 100644
--- a/tests/fe/fe_dgq_hessian_divergence_theorem.cc
+++ b/tests/fe/fe_dgq_hessian_divergence_theorem.cc
@@ -88,8 +88,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_enriched_07.cc b/tests/fe/fe_enriched_07.cc
index 486ec2c4b8..a064be323f 100644
--- a/tests/fe/fe_enriched_07.cc
+++ b/tests/fe/fe_enriched_07.cc
@@ -85,7 +85,7 @@ test6(const bool         do_href,
       const unsigned int p_feq  = 1,
       const unsigned int p_feen = 2)
 {
-  deallog << "hp: " << do_href << " " << p_feq << " " << p_feen << std::endl;
+  deallog << "hp: " << do_href << ' ' << p_feq << ' ' << p_feen << std::endl;
 
   Triangulation<dim> triangulation;
   DoFHandler<dim>    dof_handler(triangulation);
diff --git a/tests/fe/fe_enriched_08.cc b/tests/fe/fe_enriched_08.cc
index 41c1c62e15..466affac23 100644
--- a/tests/fe/fe_enriched_08.cc
+++ b/tests/fe/fe_enriched_08.cc
@@ -84,7 +84,7 @@ template <int dim>
 void
 test2cells(const unsigned int p_feq = 2, const unsigned int p_feen = 1)
 {
-  deallog << "2cells: " << dim << " " << p_feq << " " << p_feen << std::endl;
+  deallog << "2cells: " << dim << ' ' << p_feq << ' ' << p_feen << std::endl;
   Triangulation<dim> triangulation;
   {
     Triangulation<dim> triangulationL;
diff --git a/tests/fe/fe_enriched_08a.cc b/tests/fe/fe_enriched_08a.cc
index 39d00e2da4..599a8873c6 100644
--- a/tests/fe/fe_enriched_08a.cc
+++ b/tests/fe/fe_enriched_08a.cc
@@ -51,7 +51,7 @@ template <int dim>
 void
 test2cellsFESystem(const unsigned int p_feq = 2, const unsigned int p_feen = 1)
 {
-  deallog << "2cells: " << dim << " " << p_feq << " " << p_feen << std::endl;
+  deallog << "2cells: " << dim << ' ' << p_feq << ' ' << p_feen << std::endl;
   Triangulation<dim> triangulation;
   {
     Triangulation<dim> triangulationL;
diff --git a/tests/fe/fe_enriched_color_01.cc b/tests/fe/fe_enriched_color_01.cc
index f39b948b64..980240306e 100644
--- a/tests/fe/fe_enriched_color_01.cc
+++ b/tests/fe/fe_enriched_color_01.cc
@@ -98,7 +98,7 @@ test()
   for (int i = 0; i < 5; ++i)
     for (int j = 0; j < 5; ++j)
       {
-        deallog << i << ":" << j << "="
+        deallog << i << ':' << j << '='
                 << ColorEnriched::internal::find_connection_between_subdomains(
                      dof_handler, predicates[i], predicates[j])
                 << std::endl;
diff --git a/tests/fe/fe_enriched_color_03.cc b/tests/fe/fe_enriched_color_03.cc
index d3e1725e32..9a97e68513 100644
--- a/tests/fe/fe_enriched_color_03.cc
+++ b/tests/fe/fe_enriched_color_03.cc
@@ -149,7 +149,7 @@ main(int argc, char **argv)
       // 0 1 0 indicates predicate with index 2 is true in the cell.
       deallog << cell->index() << ":predicates=";
       for (auto predicate : vec_predicates)
-        deallog << predicate(cell) << ":";
+        deallog << predicate(cell) << ':';
 
       // print color predicate pairs for a cell
       // Note that here material id is used to identify cells
@@ -158,7 +158,7 @@ main(int argc, char **argv)
       for (auto color_predicate_pair :
            cellwise_color_predicate_map[cell->material_id()])
         {
-          deallog << "(" << color_predicate_pair.first << ","
+          deallog << '(' << color_predicate_pair.first << ','
                   << color_predicate_pair.second << "):";
         }
 
@@ -166,7 +166,7 @@ main(int argc, char **argv)
       //{1,2} indicates 2 enrichment functions of color 1 and 2 are relevant.
       deallog << ":fe_active_index:" << cell->active_fe_index() << ":fe_set:";
       for (auto fe_set_element : fe_sets[cell->active_fe_index()])
-        deallog << fe_set_element << ":";
+        deallog << fe_set_element << ':';
       deallog << std::endl;
     }
 
diff --git a/tests/fe/fe_enriched_color_04.cc b/tests/fe/fe_enriched_color_04.cc
index 4d5b4fc0db..2be800b73a 100644
--- a/tests/fe/fe_enriched_color_04.cc
+++ b/tests/fe/fe_enriched_color_04.cc
@@ -157,7 +157,7 @@ main(int argc, char **argv)
       unsigned int cell_id = cell->index();
       deallog << cell_id << ":predicates=";
       for (auto predicate : vec_predicates)
-        deallog << predicate(cell) << ":";
+        deallog << predicate(cell) << ':';
 
       /*
        * Check if a color and enrichment index map exists for the cell.
diff --git a/tests/fe/fe_enriched_color_05.cc b/tests/fe/fe_enriched_color_05.cc
index 6b6ffcbe19..ea7d720074 100644
--- a/tests/fe/fe_enriched_color_05.cc
+++ b/tests/fe/fe_enriched_color_05.cc
@@ -239,7 +239,7 @@ main(int argc, char **argv)
     {
       deallog << "color:";
       for (auto color : fe_set)
-        deallog << ":" << color;
+        deallog << ':' << color;
       deallog << std::endl;
     }
 
diff --git a/tests/fe/fe_enriched_color_07.cc b/tests/fe/fe_enriched_color_07.cc
index 365b571101..7f9f2fdf17 100644
--- a/tests/fe/fe_enriched_color_07.cc
+++ b/tests/fe/fe_enriched_color_07.cc
@@ -574,7 +574,7 @@ ParameterCollection::print()
   for (unsigned int i = 0; i < points_enrichments.size(); i = i + dim)
     {
       for (int d = 0; d < dim; ++d)
-        std::cout << points_enrichments[i + d] << " ";
+        std::cout << points_enrichments[i + d] << ' ';
 
       std::cout << std::endl;
     }
@@ -1003,11 +1003,11 @@ plot_shape_function(DoFHandler<dim> &dof_handler, unsigned int patches = 5)
         << std::endl;
       GridOut grid_out;
       grid_out.write_gnuplot(dof_handler.get_triangulation(), f);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
 
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       std::cout << "...finished printing support points" << std::endl;
     }
@@ -1369,12 +1369,12 @@ LaplaceProblem<dim>::build_fe_space()
             << "plot '-' using 1:2 with lines notitle, '-' with labels point pt 2 offset 1,1 notitle"
             << std::endl;
           GridOut().write_gnuplot(triangulation, f);
-          f << "e" << std::endl;
+          f << 'e' << std::endl;
 
           for (auto it : dof_handler.active_cell_iterators())
             f << it->center() << " \"" << it->active_fe_index() << "\"\n";
 
-          f << std::flush << "e" << std::endl;
+          f << std::flush << 'e' << std::endl;
           pcout << "...finished print fe indices" << std::endl;
         }
 
@@ -1399,12 +1399,12 @@ LaplaceProblem<dim>::build_fe_space()
             << "plot '-' using 1:2 with lines notitle, '-' with labels point pt 2 offset 1,1 notitle"
             << std::endl;
           GridOut().write_gnuplot(triangulation, f);
-          f << "e" << std::endl;
+          f << 'e' << std::endl;
 
           for (auto it : dof_handler.active_cell_iterators())
             f << it->center() << " \"" << it->index() << "\"\n";
 
-          f << std::flush << "e" << std::endl;
+          f << std::flush << 'e' << std::endl;
 
           pcout << "...end print cell indices" << std::endl;
         }
@@ -1726,9 +1726,9 @@ LaplaceProblem<dim>::process_solution()
     }
 
   pcout << "refinement h_smallest Dofs L2_norm H1_norm" << std::endl;
-  pcout << prm.global_refinement << " "
-        << prm.size / std::pow(2.0, prm.global_refinement) << " "
-        << dof_handler.n_dofs() << " " << L2_error << " " << H1_error
+  pcout << prm.global_refinement << ' '
+        << prm.size / std::pow(2.0, prm.global_refinement) << ' '
+        << dof_handler.n_dofs() << ' ' << L2_error << ' ' << H1_error
         << std::endl;
 }
 
diff --git a/tests/fe/fe_enriched_color_08.cc b/tests/fe/fe_enriched_color_08.cc
index 70253bcdad..6b337031ce 100644
--- a/tests/fe/fe_enriched_color_08.cc
+++ b/tests/fe/fe_enriched_color_08.cc
@@ -132,11 +132,11 @@ plot_shape_function(DoFHandler<dim> &dof_handler, unsigned int patches = 5)
         << std::endl;
       GridOut grid_out;
       grid_out.write_gnuplot(dof_handler.get_triangulation(), f);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
 
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       deallog << "...finished printing support points" << std::endl;
     }
diff --git a/tests/fe/fe_face_values_1d.cc b/tests/fe/fe_face_values_1d.cc
index 772119c8be..308feb8f4c 100644
--- a/tests/fe/fe_face_values_1d.cc
+++ b/tests/fe/fe_face_values_1d.cc
@@ -78,7 +78,7 @@ plot_faces(Mapping<dim> &                           mapping,
       // now print some data on the shape
       // functions
       for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-        deallog << "shape_function " << i << ":" << std::endl
+        deallog << "shape_function " << i << ':' << std::endl
                 << "  phi=" << fe_values.shape_value(i, 0) << std::endl
                 << "  grad phi=" << fe_values.shape_grad(i, 0) << std::endl
                 << "  grad^2 phi=" << fe_values.shape_hessian(i, 0)
@@ -124,7 +124,7 @@ plot_subfaces(Mapping<dim> &                           mapping,
         // now print some data on the shape
         // functions
         for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-          deallog << "shape_function " << i << ":" << std::endl
+          deallog << "shape_function " << i << ':' << std::endl
                   << "  phi=" << fe_values.shape_value(i, 0) << std::endl
                   << "  grad phi=" << fe_values.shape_grad(i, 0) << std::endl
                   << "  grad^2 phi=" << fe_values.shape_hessian(i, 0)
diff --git a/tests/fe/fe_nedelec_gradient_divergence_theorem.cc b/tests/fe/fe_nedelec_gradient_divergence_theorem.cc
index ea509a5177..2c3979e377 100644
--- a/tests/fe/fe_nedelec_gradient_divergence_theorem.cc
+++ b/tests/fe/fe_nedelec_gradient_divergence_theorem.cc
@@ -88,8 +88,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_nedelec_sz_face_orientation.cc b/tests/fe/fe_nedelec_sz_face_orientation.cc
index 76ed2fe713..e06ab02d5c 100644
--- a/tests/fe/fe_nedelec_sz_face_orientation.cc
+++ b/tests/fe/fe_nedelec_sz_face_orientation.cc
@@ -208,7 +208,7 @@ evaluate(const FiniteElement<3> &fe, const DoFHandler<3> &dof_handler)
         {
           deallog << "DoF#" << i << ", value=["
                   << fe_values[component].value(i, 0) << "], curl=["
-                  << fe_values[component].curl(i, 0) << "]" << std::endl;
+                  << fe_values[component].curl(i, 0) << ']' << std::endl;
         }
     }
 }
diff --git a/tests/fe/fe_nedelec_sz_gradient_divergence_theorem.cc b/tests/fe/fe_nedelec_sz_gradient_divergence_theorem.cc
index 0eca0d2fbe..bc44449d42 100644
--- a/tests/fe/fe_nedelec_sz_gradient_divergence_theorem.cc
+++ b/tests/fe/fe_nedelec_sz_gradient_divergence_theorem.cc
@@ -87,8 +87,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_q_3rd_derivative_divergence_theorem.cc b/tests/fe/fe_q_3rd_derivative_divergence_theorem.cc
index e8f26ac205..77ab2dc76d 100644
--- a/tests/fe/fe_q_3rd_derivative_divergence_theorem.cc
+++ b/tests/fe/fe_q_3rd_derivative_divergence_theorem.cc
@@ -86,8 +86,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_q_bubbles.cc b/tests/fe/fe_q_bubbles.cc
index 79660f0225..a67bb63ace 100644
--- a/tests/fe/fe_q_bubbles.cc
+++ b/tests/fe/fe_q_bubbles.cc
@@ -303,7 +303,7 @@ Step3<dim>::output_results(unsigned int i) const
   const double Linfty_error = difference_per_cell.linfty_norm();
 
   deallog << std::endl
-          << fe->get_name() << " " << i << std::endl
+          << fe->get_name() << ' ' << i << std::endl
           << "L2_error: " << L2_error << std::endl
           << "H1_error: " << H1_error << std::endl
           << "Linfty_error: " << Linfty_error << std::endl
diff --git a/tests/fe/fe_q_dg0.cc b/tests/fe/fe_q_dg0.cc
index f335505bb2..61735c118e 100644
--- a/tests/fe/fe_q_dg0.cc
+++ b/tests/fe/fe_q_dg0.cc
@@ -967,21 +967,21 @@ main()
   {
     degree = 1;
     FESystem<dim> fe(FE_Q<dim>(degree + 1), dim, FE_Q<dim>(degree), 1);
-    deallog << fe.get_name() << ":" << std::endl;
+    deallog << fe.get_name() << ':' << std::endl;
     StokesProblem<2> flow_problem(degree, fe);
     flow_problem.run();
   }
   {
     degree = 1;
     FESystem<2> fe(FE_Q<dim>(degree + 1), dim, FE_Q_DG0<dim>(degree), 1);
-    deallog << fe.get_name() << ":" << std::endl;
+    deallog << fe.get_name() << ':' << std::endl;
     StokesProblem<2> flow_problem(degree, fe);
     flow_problem.run();
   }
   {
     degree = 2;
     FESystem<2> fe(FE_Q<dim>(degree + 1), dim, FE_Q_DG0<dim>(degree), 1);
-    deallog << fe.get_name() << ":" << std::endl;
+    deallog << fe.get_name() << ':' << std::endl;
     StokesProblem<2> flow_problem(degree, fe);
     flow_problem.run();
   }
diff --git a/tests/fe/fe_q_gradient_divergence_theorem.cc b/tests/fe/fe_q_gradient_divergence_theorem.cc
index 58c30cae00..02b58b8ba6 100644
--- a/tests/fe/fe_q_gradient_divergence_theorem.cc
+++ b/tests/fe/fe_q_gradient_divergence_theorem.cc
@@ -88,8 +88,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_q_hessian_divergence_theorem.cc b/tests/fe/fe_q_hessian_divergence_theorem.cc
index 17e34e2aba..9ef7d62fd6 100644
--- a/tests/fe/fe_q_hessian_divergence_theorem.cc
+++ b/tests/fe/fe_q_hessian_divergence_theorem.cc
@@ -88,8 +88,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_q_hierarchical_3rd_derivative_divergence_theorem.cc b/tests/fe/fe_q_hierarchical_3rd_derivative_divergence_theorem.cc
index 0d6da37fad..6d5637a767 100644
--- a/tests/fe/fe_q_hierarchical_3rd_derivative_divergence_theorem.cc
+++ b/tests/fe/fe_q_hierarchical_3rd_derivative_divergence_theorem.cc
@@ -87,8 +87,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_rannacher_turek_01.cc b/tests/fe/fe_rannacher_turek_01.cc
index ddde81f09b..784a3bf4ae 100644
--- a/tests/fe/fe_rannacher_turek_01.cc
+++ b/tests/fe/fe_rannacher_turek_01.cc
@@ -95,7 +95,7 @@ test_nodal_matrix()
               deallog << N(i, j) - 0.0;
             }
           if (j + 1 < 4)
-            deallog << " ";
+            deallog << ' ';
           else
             deallog << std::endl;
         }
@@ -142,7 +142,7 @@ test_interpolation()
 
       for (unsigned int j = 0; j < n_dofs; ++j)
         {
-          deallog << local_dofs[j] - interpolated_local_dofs[j] << " ";
+          deallog << local_dofs[j] - interpolated_local_dofs[j] << ' ';
         }
       deallog << std::endl;
     }
diff --git a/tests/fe/fe_rannacher_turek_02.cc b/tests/fe/fe_rannacher_turek_02.cc
index 4fbe7402b2..29beaa8984 100644
--- a/tests/fe/fe_rannacher_turek_02.cc
+++ b/tests/fe/fe_rannacher_turek_02.cc
@@ -53,10 +53,10 @@ test_values()
     {
       for (unsigned int q = 0; q < quadrature.size(); ++q)
         {
-          deallog << fev.shape_value(i, q) << " ";
+          deallog << fev.shape_value(i, q) << ' ';
           for (unsigned int d = 0; d < 2; ++d)
             {
-              deallog << fev.shape_grad(i, q)[d] << " ";
+              deallog << fev.shape_grad(i, q)[d] << ' ';
             }
         }
       deallog << std::endl;
diff --git a/tests/fe/fe_rt_gradient_divergence_theorem.cc b/tests/fe/fe_rt_gradient_divergence_theorem.cc
index 2549a982af..69d2e396a3 100644
--- a/tests/fe/fe_rt_gradient_divergence_theorem.cc
+++ b/tests/fe/fe_rt_gradient_divergence_theorem.cc
@@ -88,8 +88,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_rt_hessian_divergence_theorem.cc b/tests/fe/fe_rt_hessian_divergence_theorem.cc
index d3d1448c1c..975822f0c3 100644
--- a/tests/fe/fe_rt_hessian_divergence_theorem.cc
+++ b/tests/fe/fe_rt_hessian_divergence_theorem.cc
@@ -84,7 +84,7 @@ test(const Triangulation<dim> &tr,
 
       deallog << "Cell nodes:" << std::endl;
       for (const unsigned int i : GeometryInfo<dim>::vertex_indices())
-        deallog << i << ": (" << cell->vertex(i) << ")" << std::endl;
+        deallog << i << ": (" << cell->vertex(i) << ')' << std::endl;
 
       bool cell_ok = true;
 
diff --git a/tests/fe/fe_series_01.cc b/tests/fe/fe_series_01.cc
index 2c580446e1..740145f8de 100644
--- a/tests/fe/fe_series_01.cc
+++ b/tests/fe/fe_series_01.cc
@@ -82,11 +82,11 @@ test_1d()
 
   deallog << "calculated:" << std::endl;
   for (unsigned int i = 0; i < N; ++i)
-    deallog << fourier_coefficients[i].real() << " "
+    deallog << fourier_coefficients[i].real() << ' '
             << fourier_coefficients[i].imag() << std::endl;
   deallog << "exact:" << std::endl;
   for (unsigned int i = 0; i < N; ++i)
-    deallog << exact[i].real() << " " << exact[i].imag() << std::endl;
+    deallog << exact[i].real() << ' ' << exact[i].imag() << std::endl;
 }
 
 
diff --git a/tests/fe/fe_series_02.cc b/tests/fe/fe_series_02.cc
index 9fe5bdf87c..e1d1128efe 100644
--- a/tests/fe/fe_series_02.cc
+++ b/tests/fe/fe_series_02.cc
@@ -132,12 +132,12 @@ test(const LegendreFunction<dim> &func, const unsigned int poly_degree)
   }
 
   for (unsigned int i = 0; i < coeff_in.size(); ++i)
-    deallog << coeff_in[i] << " ";
+    deallog << coeff_in[i] << ' ';
 
   deallog << std::endl;
 
   for (unsigned int i = 0; i < N; ++i)
-    deallog << coeff_out[i] << " ";
+    deallog << coeff_out[i] << ' ';
 
   deallog << std::endl;
 
diff --git a/tests/fe/fe_series_04.cc b/tests/fe/fe_series_04.cc
index 4867a3e1b0..3823a97dad 100644
--- a/tests/fe/fe_series_04.cc
+++ b/tests/fe/fe_series_04.cc
@@ -128,7 +128,7 @@ test(const LegendreFunction<dim> &func, const unsigned int poly_degree)
 
     deallog << "local dofs:";
     for (unsigned int i = 0; i < cell_n_dofs; ++i)
-      dealii::deallog << " " << local_dof_values[i];
+      dealii::deallog << ' ' << local_dof_values[i];
 
     dealii::deallog << std::endl;
   }
@@ -163,7 +163,7 @@ test_legendre_orthonormal(const unsigned int N)
     {
       deallog << "l=" << l << ": ";
       for (double x = -1.0; x <= 1.0; x += 1.0)
-        deallog << std_cxx17::legendre(l, x) << " ";
+        deallog << std_cxx17::legendre(l, x) << ' ';
 
       deallog << std::endl;
     }
@@ -187,7 +187,7 @@ test_legendre_orthonormal(const unsigned int N)
           }
         ortho *= (1.0 + k1 + k2) / 2.0;
 
-        deallog << "(" << k1 << "," << k2 << ") = " << ortho << std::endl;
+        deallog << '(' << k1 << ',' << k2 << ") = " << ortho << std::endl;
       }
   deallog << std::endl;
 }
diff --git a/tests/fe/fe_series_05.cc b/tests/fe/fe_series_05.cc
index f56908b017..687c8b6e81 100644
--- a/tests/fe/fe_series_05.cc
+++ b/tests/fe/fe_series_05.cc
@@ -112,7 +112,7 @@ print(const Table<2, double> &coeff)
 {
   for (unsigned int i = 0; i < coeff.size(0); ++i)
     for (unsigned int j = 0; j < coeff.size(1); ++j)
-      deallog << coeff(i, j) << " ";
+      deallog << coeff(i, j) << ' ';
   deallog << std::endl;
 }
 
@@ -122,7 +122,7 @@ print(const Table<3, double> &coeff)
   for (unsigned int i = 0; i < coeff.size(0); ++i)
     for (unsigned int j = 0; j < coeff.size(1); ++j)
       for (unsigned int k = 0; k < coeff.size(2); ++k)
-        deallog << coeff(i, j, k) << " ";
+        deallog << coeff(i, j, k) << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/fe/fe_series_08.cc b/tests/fe/fe_series_08.cc
index c948f485a2..4974ff9750 100644
--- a/tests/fe/fe_series_08.cc
+++ b/tests/fe/fe_series_08.cc
@@ -42,8 +42,8 @@ test()
 
   std::pair<double, double> fit = FESeries::linear_regression(x, y);
 
-  deallog << "exact:      " << k_in << " " << b_in << std::endl;
-  deallog << "calculated: " << fit.first << " " << fit.second << std::endl;
+  deallog << "exact:      " << k_in << ' ' << b_in << std::endl;
+  deallog << "calculated: " << fit.first << ' ' << fit.second << std::endl;
 }
 
 
diff --git a/tests/fe/fe_system_3rd_derivative_divergence_theorem.cc b/tests/fe/fe_system_3rd_derivative_divergence_theorem.cc
index ed706003e4..510bf60551 100644
--- a/tests/fe/fe_system_3rd_derivative_divergence_theorem.cc
+++ b/tests/fe/fe_system_3rd_derivative_divergence_theorem.cc
@@ -86,8 +86,8 @@ test(const Triangulation<dim> &tr,
         {
           deallog << i << ": ( ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << cell->vertex(i)[d] << " ";
-          deallog << ")" << std::endl;
+            deallog << cell->vertex(i)[d] << ' ';
+          deallog << ')' << std::endl;
         }
 
       bool cell_ok = true;
diff --git a/tests/fe/fe_system_components_base.cc b/tests/fe/fe_system_components_base.cc
index b2fbb80b3b..c4b9780297 100644
--- a/tests/fe/fe_system_components_base.cc
+++ b/tests/fe/fe_system_components_base.cc
@@ -106,10 +106,10 @@ test(const bool renumber = false)
         << "plot '-' using 1:2 with lines notitle, '-' with labels point pt 2 offset 0.5,0.5 notitle"
         << std::endl;
       GridOut().write_gnuplot(triangulation, f);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
     }
 }
 
diff --git a/tests/fe/fe_system_generalized_support_points.cc b/tests/fe/fe_system_generalized_support_points.cc
index dd83f1a064..44fdf059b8 100644
--- a/tests/fe/fe_system_generalized_support_points.cc
+++ b/tests/fe/fe_system_generalized_support_points.cc
@@ -34,7 +34,7 @@ test()
     deallog << fe.get_name() << std::endl;
     for (auto it : fe.get_generalized_support_points())
       {
-        deallog << "(" << it[0] << "," << it[1] << ") ";
+        deallog << '(' << it[0] << ',' << it[1] << ") ";
       }
     deallog << std::endl;
   };
diff --git a/tests/fe/fe_tools.cc b/tests/fe/fe_tools.cc
index 5a0d2ef2d6..5dca92f5a9 100644
--- a/tests/fe/fe_tools.cc
+++ b/tests/fe/fe_tools.cc
@@ -42,7 +42,7 @@ print_formatted(const FullMatrix<number> &A,
             deallog << std::setw(width) << std::setprecision(precision)
                     << A(i, j);
           else
-            deallog << std::setw(width) << std::setprecision(precision) << "~";
+            deallog << std::setw(width) << std::setprecision(precision) << '~';
           deallog << ' ';
         };
       deallog << std::endl;
diff --git a/tests/fe/fe_values_view_16.cc b/tests/fe/fe_values_view_16.cc
index 9850c16fe4..f98cdf7156 100644
--- a/tests/fe/fe_values_view_16.cc
+++ b/tests/fe/fe_values_view_16.cc
@@ -82,7 +82,7 @@ test(const Triangulation<dim> &tr, const FiniteElement<dim> &fe)
             {
               for (unsigned int e = 0; e < dim; ++e)
                 for (unsigned int f = 0; f < dim; ++f)
-                  deallog << selected_vector_values[q][d][e][f] << " ";
+                  deallog << selected_vector_values[q][d][e][f] << ' ';
               deallog << std::endl;
               Assert((selected_vector_values[q][d] - vector_values[q][c + d])
                          .norm() <= 1e-12 * selected_vector_values[q][d].norm(),
diff --git a/tests/fe/fe_values_view_21.cc b/tests/fe/fe_values_view_21.cc
index 4dcca4b0ff..00bdbe8c85 100644
--- a/tests/fe/fe_values_view_21.cc
+++ b/tests/fe/fe_values_view_21.cc
@@ -125,7 +125,7 @@ MixedElastoPlasticity<dim>::make_grid_and_dofs()
           << std::endl
           << "Total number of cells: " << triangulation.n_cells() << std::endl
           << "Number of degrees of freedom: " << dof_handler.n_dofs() << " = ("
-          << n_stress_dof << " + " << n_gamma_dof << ")" << std::endl;
+          << n_stress_dof << " + " << n_gamma_dof << ')' << std::endl;
 
   // following step-22 use of simple
   // compressed block sparsity
diff --git a/tests/fe/fe_values_view_21_nonsymmetric.cc b/tests/fe/fe_values_view_21_nonsymmetric.cc
index 267ed0fc20..1e643de991 100644
--- a/tests/fe/fe_values_view_21_nonsymmetric.cc
+++ b/tests/fe/fe_values_view_21_nonsymmetric.cc
@@ -126,7 +126,7 @@ MixedElastoPlasticity<dim>::make_grid_and_dofs()
           << std::endl
           << "Total number of cells: " << triangulation.n_cells() << std::endl
           << "Number of degrees of freedom: " << dof_handler.n_dofs() << " = ("
-          << n_stress_dof << " + " << n_gamma_dof << ")" << std::endl;
+          << n_stress_dof << " + " << n_gamma_dof << ')' << std::endl;
 
   // following step-22 use of simple
   // compressed block sparsity
diff --git a/tests/fe/fe_values_view_22.cc b/tests/fe/fe_values_view_22.cc
index a00d82dfee..3d1a44e1c5 100644
--- a/tests/fe/fe_values_view_22.cc
+++ b/tests/fe/fe_values_view_22.cc
@@ -119,7 +119,7 @@ MixedElastoPlasticity<dim>::make_grid_and_dofs()
           << std::endl
           << "Total number of cells: " << triangulation.n_cells() << std::endl
           << "Number of degrees of freedom: " << dof_handler.n_dofs() << " = ("
-          << n_stress_dof << " + " << n_gamma_dof << ")" << std::endl;
+          << n_stress_dof << " + " << n_gamma_dof << ')' << std::endl;
 
   {
     BlockDynamicSparsityPattern csp(2, 2);
diff --git a/tests/fe/fe_values_view_tensor_01.cc b/tests/fe/fe_values_view_tensor_01.cc
index 559dcccbe8..1b8d467613 100644
--- a/tests/fe/fe_values_view_tensor_01.cc
+++ b/tests/fe/fe_values_view_tensor_01.cc
@@ -123,7 +123,7 @@ MixedElastoPlasticity<dim>::make_grid_and_dofs()
           << std::endl
           << "Total number of cells: " << triangulation.n_cells() << std::endl
           << "Number of degrees of freedom: " << dof_handler.n_dofs() << " = ("
-          << n_stress_dof << " + " << n_gamma_dof << ")" << std::endl;
+          << n_stress_dof << " + " << n_gamma_dof << ')' << std::endl;
 
   // following step-22 use of simple compressed block sparsity pattern for
   // efficiency
@@ -193,7 +193,7 @@ MixedElastoPlasticity<dim>::assemble_system()
   unsigned int cc = 0;
   for (; cell != endc; ++cell) // loop over all cells
     {
-      deallog << ++cc << " ";
+      deallog << ++cc << ' ';
       cell_matrix = 0;
       cell_rhs    = 0;
 
@@ -225,9 +225,9 @@ check()
             TableIndices<2> indices(i, j);
             unsigned int    unrolled =
               Tensor<2, dim>::component_to_unrolled_index(indices);
-            deallog << i << " " << j << " -> " << unrolled << std::endl;
+            deallog << i << ' ' << j << " -> " << unrolled << std::endl;
             indices = Tensor<2, dim>::unrolled_to_component_indices(unrolled);
-            deallog << unrolled << " -> " << indices[0] << " " << indices[1]
+            deallog << unrolled << " -> " << indices[0] << ' ' << indices[1]
                     << std::endl;
           }
       }
diff --git a/tests/fe/fe_values_views_types.cc b/tests/fe/fe_values_views_types.cc
index 8b8058d331..8950c64fe2 100644
--- a/tests/fe/fe_values_views_types.cc
+++ b/tests/fe/fe_values_views_types.cc
@@ -33,7 +33,7 @@ test(const Extractor &)
     template solution_gradient_type<double>
       t2;
 
-  deallog << "Test<" << Utilities::dim_string(dim, spacedim) << ">" << std::endl
+  deallog << "Test<" << Utilities::dim_string(dim, spacedim) << '>' << std::endl
           << Utilities::type_to_string(t1) << std::endl
           << Utilities::type_to_string(t2) << std::endl;
 }
diff --git a/tests/fe/injection_q_dg0.cc b/tests/fe/injection_q_dg0.cc
index 9db1e6507f..c3ae8a3d70 100644
--- a/tests/fe/injection_q_dg0.cc
+++ b/tests/fe/injection_q_dg0.cc
@@ -30,7 +30,7 @@ test()
   for (unsigned int i = 1; i < 4; ++i)
     for (unsigned int j = i; j < 4; ++j)
       {
-        deallog << "inj " << i << " " << j << ":" << std::endl;
+        deallog << "inj " << i << ' ' << j << ':' << std::endl;
         do_check(FE_Q_DG0<dim>(QIterated<1>(QTrapezoid<1>(), i)),
                  FE_Q_DG0<dim>(QIterated<1>(QTrapezoid<1>(), j)));
       }
diff --git a/tests/fe/jacobians.cc b/tests/fe/jacobians.cc
index 56c2105759..738a40f660 100644
--- a/tests/fe/jacobians.cc
+++ b/tests/fe/jacobians.cc
@@ -62,7 +62,7 @@ do_test(const Triangulation<dim> &tria, const Mapping<dim> &mapping)
 
         for (unsigned int d = 0; d < dim; ++d)
           for (unsigned int e = 0; e < dim; ++e)
-            deallog << fe_val.jacobian(0)[d][e] << " ";
+            deallog << fe_val.jacobian(0)[d][e] << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
@@ -79,7 +79,7 @@ do_test(const Triangulation<dim> &tria, const Mapping<dim> &mapping)
 
         for (unsigned int d = 0; d < dim; ++d)
           for (unsigned int e = 0; e < dim; ++e)
-            deallog << fe_val.inverse_jacobian(0)[d][e] << " ";
+            deallog << fe_val.inverse_jacobian(0)[d][e] << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
@@ -97,7 +97,7 @@ do_test(const Triangulation<dim> &tria, const Mapping<dim> &mapping)
         for (unsigned int d = 0; d < dim; ++d)
           for (unsigned int e = 0; e < dim; ++e)
             for (unsigned int f = 0; f < dim; ++f)
-              deallog << fe_val.jacobian_grad(0)[d][e][f] << " ";
+              deallog << fe_val.jacobian_grad(0)[d][e][f] << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
@@ -118,7 +118,7 @@ do_test(const Triangulation<dim> &tria, const Mapping<dim> &mapping)
         for (unsigned int d = 0; d < dim; ++d)
           for (unsigned int e = 0; e < dim; ++e)
             for (unsigned int f = 0; f < dim; ++f)
-              deallog << fe_val.jacobian_pushed_forward_grad(0)[d][e][f] << " ";
+              deallog << fe_val.jacobian_pushed_forward_grad(0)[d][e][f] << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
@@ -137,7 +137,7 @@ do_test(const Triangulation<dim> &tria, const Mapping<dim> &mapping)
           for (unsigned int e = 0; e < dim; ++e)
             for (unsigned int f = 0; f < dim; ++f)
               for (unsigned int g = 0; g < dim; ++g)
-                deallog << fe_val.jacobian_2nd_derivative(0)[d][e][f][g] << " ";
+                deallog << fe_val.jacobian_2nd_derivative(0)[d][e][f][g] << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
@@ -161,7 +161,7 @@ do_test(const Triangulation<dim> &tria, const Mapping<dim> &mapping)
               for (unsigned int g = 0; g < dim; ++g)
                 deallog << fe_val.jacobian_pushed_forward_2nd_derivative(
                              0)[d][e][f][g]
-                        << " ";
+                        << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
@@ -182,7 +182,7 @@ do_test(const Triangulation<dim> &tria, const Mapping<dim> &mapping)
               for (unsigned int g = 0; g < dim; ++g)
                 for (unsigned int h = 0; h < dim; ++h)
                   deallog << fe_val.jacobian_3rd_derivative(0)[d][e][f][g][h]
-                          << " ";
+                          << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
@@ -208,7 +208,7 @@ do_test(const Triangulation<dim> &tria, const Mapping<dim> &mapping)
                 for (unsigned int h = 0; h < dim; ++h)
                   deallog << fe_val.jacobian_pushed_forward_3rd_derivative(
                                0)[d][e][f][g][h]
-                          << " ";
+                          << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
diff --git a/tests/fe/jacobians_face.cc b/tests/fe/jacobians_face.cc
index 0e0def791c..3857438551 100644
--- a/tests/fe/jacobians_face.cc
+++ b/tests/fe/jacobians_face.cc
@@ -65,7 +65,7 @@ test()
 
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
-              deallog << fe_val.jacobian(0)[d][e] << " ";
+              deallog << fe_val.jacobian(0)[d][e] << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -78,7 +78,7 @@ test()
 
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
-                  deallog << fe_sub_val.jacobian(0)[d][e] << " ";
+                  deallog << fe_sub_val.jacobian(0)[d][e] << ' ';
               deallog << std::endl;
             }
         }
@@ -103,7 +103,7 @@ test()
 
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
-              deallog << fe_val.inverse_jacobian(0)[d][e] << " ";
+              deallog << fe_val.inverse_jacobian(0)[d][e] << ' ';
           deallog << std::endl;
 
           // Also check the inverse Jacobian with FESubfaceValues
@@ -116,7 +116,7 @@ test()
 
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
-                  deallog << fe_sub_val.inverse_jacobian(0)[d][e] << " ";
+                  deallog << fe_sub_val.inverse_jacobian(0)[d][e] << ' ';
               deallog << std::endl;
             }
         }
@@ -142,7 +142,7 @@ test()
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
               for (unsigned int f = 0; f < dim; ++f)
-                deallog << fe_val.jacobian_grad(0)[d][e][f] << " ";
+                deallog << fe_val.jacobian_grad(0)[d][e][f] << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -156,7 +156,7 @@ test()
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
                   for (unsigned int f = 0; f < dim; ++f)
-                    deallog << fe_sub_val.jacobian_grad(0)[d][e][f] << " ";
+                    deallog << fe_sub_val.jacobian_grad(0)[d][e][f] << ' ';
               deallog << std::endl;
             }
         }
@@ -186,7 +186,7 @@ test()
             for (unsigned int e = 0; e < dim; ++e)
               for (unsigned int f = 0; f < dim; ++f)
                 deallog << fe_val.jacobian_pushed_forward_grad(0)[d][e][f]
-                        << " ";
+                        << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -202,7 +202,7 @@ test()
                   for (unsigned int f = 0; f < dim; ++f)
                     deallog
                       << fe_sub_val.jacobian_pushed_forward_grad(0)[d][e][f]
-                      << " ";
+                      << ' ';
               deallog << std::endl;
             }
         }
@@ -233,7 +233,7 @@ test()
               for (unsigned int f = 0; f < dim; ++f)
                 for (unsigned int g = 0; g < dim; ++g)
                   deallog << fe_val.jacobian_2nd_derivative(0)[d][e][f][g]
-                          << " ";
+                          << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -250,7 +250,7 @@ test()
                     for (unsigned int g = 0; g < dim; ++g)
                       deallog
                         << fe_sub_val.jacobian_2nd_derivative(0)[d][e][f][g]
-                        << " ";
+                        << ' ';
               deallog << std::endl;
             }
         }
@@ -280,7 +280,7 @@ test()
                 for (unsigned int g = 0; g < dim; ++g)
                   deallog << fe_val.jacobian_pushed_forward_2nd_derivative(
                                0)[d][e][f][g]
-                          << " ";
+                          << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -298,7 +298,7 @@ test()
                       deallog
                         << fe_sub_val.jacobian_pushed_forward_2nd_derivative(
                              0)[d][e][f][g]
-                        << " ";
+                        << ' ';
               deallog << std::endl;
             }
         }
@@ -330,7 +330,7 @@ test()
                 for (unsigned int g = 0; g < dim; ++g)
                   for (unsigned int h = 0; h < dim; ++h)
                     deallog << fe_val.jacobian_3rd_derivative(0)[d][e][f][g][h]
-                            << " ";
+                            << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -348,7 +348,7 @@ test()
                       for (unsigned int h = 0; h < dim; ++h)
                         deallog << fe_sub_val.jacobian_3rd_derivative(
                                      0)[d][e][f][g][h]
-                                << " ";
+                                << ' ';
               deallog << std::endl;
             }
         }
@@ -380,7 +380,7 @@ test()
                   for (unsigned int h = 0; h < dim; ++h)
                     deallog << fe_val.jacobian_pushed_forward_3rd_derivative(
                                  0)[d][e][f][g][h]
-                            << " ";
+                            << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -399,7 +399,7 @@ test()
                         deallog
                           << fe_sub_val.jacobian_pushed_forward_3rd_derivative(
                                0)[d][e][f][g][h]
-                          << " ";
+                          << ' ';
               deallog << std::endl;
             }
         }
diff --git a/tests/fe/jacobians_face_cartesian.cc b/tests/fe/jacobians_face_cartesian.cc
index 892479f9c0..8cf7364612 100644
--- a/tests/fe/jacobians_face_cartesian.cc
+++ b/tests/fe/jacobians_face_cartesian.cc
@@ -63,7 +63,7 @@ test()
 
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
-              deallog << fe_val.jacobian(0)[d][e] << " ";
+              deallog << fe_val.jacobian(0)[d][e] << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -76,7 +76,7 @@ test()
 
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
-                  deallog << fe_sub_val.jacobian(0)[d][e] << " ";
+                  deallog << fe_sub_val.jacobian(0)[d][e] << ' ';
               deallog << std::endl;
             }
         }
@@ -101,7 +101,7 @@ test()
 
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
-              deallog << fe_val.inverse_jacobian(0)[d][e] << " ";
+              deallog << fe_val.inverse_jacobian(0)[d][e] << ' ';
           deallog << std::endl;
 
           // Also check the inverse Jacobian with FESubfaceValues
@@ -114,7 +114,7 @@ test()
 
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
-                  deallog << fe_sub_val.inverse_jacobian(0)[d][e] << " ";
+                  deallog << fe_sub_val.inverse_jacobian(0)[d][e] << ' ';
               deallog << std::endl;
             }
         }
@@ -140,7 +140,7 @@ test()
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
               for (unsigned int f = 0; f < dim; ++f)
-                deallog << fe_val.jacobian_grad(0)[d][e][f] << " ";
+                deallog << fe_val.jacobian_grad(0)[d][e][f] << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -154,7 +154,7 @@ test()
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
                   for (unsigned int f = 0; f < dim; ++f)
-                    deallog << fe_sub_val.jacobian_grad(0)[d][e][f] << " ";
+                    deallog << fe_sub_val.jacobian_grad(0)[d][e][f] << ' ';
               deallog << std::endl;
             }
         }
@@ -184,7 +184,7 @@ test()
             for (unsigned int e = 0; e < dim; ++e)
               for (unsigned int f = 0; f < dim; ++f)
                 deallog << fe_val.jacobian_pushed_forward_grad(0)[d][e][f]
-                        << " ";
+                        << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -200,7 +200,7 @@ test()
                   for (unsigned int f = 0; f < dim; ++f)
                     deallog
                       << fe_sub_val.jacobian_pushed_forward_grad(0)[d][e][f]
-                      << " ";
+                      << ' ';
               deallog << std::endl;
             }
         }
@@ -231,7 +231,7 @@ test()
               for (unsigned int f = 0; f < dim; ++f)
                 for (unsigned int g = 0; g < dim; ++g)
                   deallog << fe_val.jacobian_2nd_derivative(0)[d][e][f][g]
-                          << " ";
+                          << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -248,7 +248,7 @@ test()
                     for (unsigned int g = 0; g < dim; ++g)
                       deallog
                         << fe_sub_val.jacobian_2nd_derivative(0)[d][e][f][g]
-                        << " ";
+                        << ' ';
               deallog << std::endl;
             }
         }
@@ -278,7 +278,7 @@ test()
                 for (unsigned int g = 0; g < dim; ++g)
                   deallog << fe_val.jacobian_pushed_forward_2nd_derivative(
                                0)[d][e][f][g]
-                          << " ";
+                          << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -296,7 +296,7 @@ test()
                       deallog
                         << fe_sub_val.jacobian_pushed_forward_2nd_derivative(
                              0)[d][e][f][g]
-                        << " ";
+                        << ' ';
               deallog << std::endl;
             }
         }
@@ -328,7 +328,7 @@ test()
                 for (unsigned int g = 0; g < dim; ++g)
                   for (unsigned int h = 0; h < dim; ++h)
                     deallog << fe_val.jacobian_3rd_derivative(0)[d][e][f][g][h]
-                            << " ";
+                            << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -346,7 +346,7 @@ test()
                       for (unsigned int h = 0; h < dim; ++h)
                         deallog << fe_sub_val.jacobian_3rd_derivative(
                                      0)[d][e][f][g][h]
-                                << " ";
+                                << ' ';
               deallog << std::endl;
             }
         }
@@ -378,7 +378,7 @@ test()
                   for (unsigned int h = 0; h < dim; ++h)
                     deallog << fe_val.jacobian_pushed_forward_3rd_derivative(
                                  0)[d][e][f][g][h]
-                            << " ";
+                            << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -397,7 +397,7 @@ test()
                         deallog
                           << fe_sub_val.jacobian_pushed_forward_3rd_derivative(
                                0)[d][e][f][g][h]
-                          << " ";
+                          << ' ';
               deallog << std::endl;
             }
         }
diff --git a/tests/fe/jacobians_face_fe_field.cc b/tests/fe/jacobians_face_fe_field.cc
index 23e2f2d5e7..a4a765abdf 100644
--- a/tests/fe/jacobians_face_fe_field.cc
+++ b/tests/fe/jacobians_face_fe_field.cc
@@ -81,7 +81,7 @@ test()
 
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
-              deallog << fe_val.jacobian(0)[d][e] << " ";
+              deallog << fe_val.jacobian(0)[d][e] << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -94,7 +94,7 @@ test()
 
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
-                  deallog << fe_sub_val.jacobian(0)[d][e] << " ";
+                  deallog << fe_sub_val.jacobian(0)[d][e] << ' ';
               deallog << std::endl;
             }
         }
@@ -119,7 +119,7 @@ test()
 
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
-              deallog << fe_val.inverse_jacobian(0)[d][e] << " ";
+              deallog << fe_val.inverse_jacobian(0)[d][e] << ' ';
           deallog << std::endl;
 
           // Also check the inverse Jacobian with FESubfaceValues
@@ -132,7 +132,7 @@ test()
 
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
-                  deallog << fe_sub_val.inverse_jacobian(0)[d][e] << " ";
+                  deallog << fe_sub_val.inverse_jacobian(0)[d][e] << ' ';
               deallog << std::endl;
             }
         }
@@ -158,7 +158,7 @@ test()
           for (unsigned int d = 0; d < dim; ++d)
             for (unsigned int e = 0; e < dim; ++e)
               for (unsigned int f = 0; f < dim; ++f)
-                deallog << fe_val.jacobian_grad(0)[d][e][f] << " ";
+                deallog << fe_val.jacobian_grad(0)[d][e][f] << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -172,7 +172,7 @@ test()
               for (unsigned int d = 0; d < dim; ++d)
                 for (unsigned int e = 0; e < dim; ++e)
                   for (unsigned int f = 0; f < dim; ++f)
-                    deallog << fe_sub_val.jacobian_grad(0)[d][e][f] << " ";
+                    deallog << fe_sub_val.jacobian_grad(0)[d][e][f] << ' ';
               deallog << std::endl;
             }
         }
@@ -202,7 +202,7 @@ test()
             for (unsigned int e = 0; e < dim; ++e)
               for (unsigned int f = 0; f < dim; ++f)
                 deallog << fe_val.jacobian_pushed_forward_grad(0)[d][e][f]
-                        << " ";
+                        << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -218,7 +218,7 @@ test()
                   for (unsigned int f = 0; f < dim; ++f)
                     deallog
                       << fe_sub_val.jacobian_pushed_forward_grad(0)[d][e][f]
-                      << " ";
+                      << ' ';
               deallog << std::endl;
             }
         }
@@ -249,7 +249,7 @@ test()
               for (unsigned int f = 0; f < dim; ++f)
                 for (unsigned int g = 0; g < dim; ++g)
                   deallog << fe_val.jacobian_2nd_derivative(0)[d][e][f][g]
-                          << " ";
+                          << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -266,7 +266,7 @@ test()
                     for (unsigned int g = 0; g < dim; ++g)
                       deallog
                         << fe_sub_val.jacobian_2nd_derivative(0)[d][e][f][g]
-                        << " ";
+                        << ' ';
               deallog << std::endl;
             }
         }
@@ -296,7 +296,7 @@ test()
                 for (unsigned int g = 0; g < dim; ++g)
                   deallog << fe_val.jacobian_pushed_forward_2nd_derivative(
                                0)[d][e][f][g]
-                          << " ";
+                          << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -314,7 +314,7 @@ test()
                       deallog
                         << fe_sub_val.jacobian_pushed_forward_2nd_derivative(
                              0)[d][e][f][g]
-                        << " ";
+                        << ' ';
               deallog << std::endl;
             }
         }
@@ -346,7 +346,7 @@ test()
                 for (unsigned int g = 0; g < dim; ++g)
                   for (unsigned int h = 0; h < dim; ++h)
                     deallog << fe_val.jacobian_3rd_derivative(0)[d][e][f][g][h]
-                            << " ";
+                            << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -364,7 +364,7 @@ test()
                       for (unsigned int h = 0; h < dim; ++h)
                         deallog << fe_sub_val.jacobian_3rd_derivative(
                                      0)[d][e][f][g][h]
-                                << " ";
+                                << ' ';
               deallog << std::endl;
             }
         }
@@ -396,7 +396,7 @@ test()
                   for (unsigned int h = 0; h < dim; ++h)
                     deallog << fe_val.jacobian_pushed_forward_3rd_derivative(
                                  0)[d][e][f][g][h]
-                            << " ";
+                            << ' ';
           deallog << std::endl;
 
           // Also check the Jacobian with FESubfaceValues
@@ -415,7 +415,7 @@ test()
                         deallog
                           << fe_sub_val.jacobian_pushed_forward_3rd_derivative(
                                0)[d][e][f][g][h]
-                          << " ";
+                          << ' ';
               deallog << std::endl;
             }
         }
diff --git a/tests/fe/nedelec_3.cc b/tests/fe/nedelec_3.cc
index 6b36093457..0cd2c4f861 100644
--- a/tests/fe/nedelec_3.cc
+++ b/tests/fe/nedelec_3.cc
@@ -101,7 +101,7 @@ check(const unsigned int p)
           for (unsigned int d = 0; d < dim; ++d)
             deallog << (d == 0 ? "" : " ") << shape_values[q](d);
 
-          deallog << "]" << std::endl;
+          deallog << ']' << std::endl;
         };
 
       deallog << std::endl;
diff --git a/tests/fe/restrict_prolongation_01.cc b/tests/fe/restrict_prolongation_01.cc
index 863aabf6b1..cef74e77fc 100644
--- a/tests/fe/restrict_prolongation_01.cc
+++ b/tests/fe/restrict_prolongation_01.cc
@@ -143,7 +143,7 @@ check(const FiniteElement<dim, spacedim> &fe,
             const double expected = (i == j) ? 1. : 0.;
             if (std::fabs(result(i, j) - expected) > 1.e-12)
               {
-                deallog << i << " " << j << " " << result(i, j) << std::endl;
+                deallog << i << ' ' << j << ' ' << result(i, j) << std::endl;
                 is_identity = false;
               }
           }
diff --git a/tests/fe/rt_1.cc b/tests/fe/rt_1.cc
index 9970f86e6c..ca4fb4ee22 100644
--- a/tests/fe/rt_1.cc
+++ b/tests/fe/rt_1.cc
@@ -60,7 +60,7 @@ plot_shape_functions(const unsigned int degree)
             for (unsigned int i = 0; i < fe_rt.dofs_per_cell; ++i)
               {
                 for (unsigned int c = 0; c < dim; ++c)
-                  deallog << " " << fe_rt.shape_value_component(i, p, c);
+                  deallog << ' ' << fe_rt.shape_value_component(i, p, c);
                 deallog << "  ";
               }
             deallog << std::endl << "grad " << p;
diff --git a/tests/fe/rt_13.cc b/tests/fe/rt_13.cc
index b441fdddb2..9570fb498b 100644
--- a/tests/fe/rt_13.cc
+++ b/tests/fe/rt_13.cc
@@ -80,7 +80,7 @@ test(const unsigned int degree)
               deallog << "[ ";
               for (unsigned int c = 0; c < fe_rt.n_components(); ++c)
                 deallog << fe_values.shape_grad_component(i, q, c) << ' ';
-              deallog << "]";
+              deallog << ']';
             }
           deallog << std::endl;
         }
diff --git a/tests/fe/rt_3.cc b/tests/fe/rt_3.cc
index 0cea911d56..b1c0938ec7 100644
--- a/tests/fe/rt_3.cc
+++ b/tests/fe/rt_3.cc
@@ -31,7 +31,7 @@ template <int dim>
 void
 test(const unsigned int degree)
 {
-  deallog << "FE_RaviartThomas<" << dim << "> (" << degree << ")" << std::endl;
+  deallog << "FE_RaviartThomas<" << dim << "> (" << degree << ')' << std::endl;
 
   FE_RaviartThomas<dim>     fe_rt(degree);
   const FullMatrix<double> &constraints = fe_rt.constraints();
diff --git a/tests/fe/rt_5.cc b/tests/fe/rt_5.cc
index 7b45d4e239..4092710149 100644
--- a/tests/fe/rt_5.cc
+++ b/tests/fe/rt_5.cc
@@ -31,7 +31,7 @@ template <int dim>
 void
 test(const unsigned int degree)
 {
-  deallog << "FE_RaviartThomas<" << dim << "> (" << degree << ")" << std::endl;
+  deallog << "FE_RaviartThomas<" << dim << "> (" << degree << ')' << std::endl;
 
   FE_RaviartThomas<dim> fe_rt(degree);
 
diff --git a/tests/fe/rt_7.cc b/tests/fe/rt_7.cc
index 8cbed35d8a..c1143b0bfe 100644
--- a/tests/fe/rt_7.cc
+++ b/tests/fe/rt_7.cc
@@ -66,11 +66,11 @@ plot_shape_functions(const unsigned int degree)
       if (q_point % QIterated<1>(q_trapez, div).size() == 0)
         deallog << std::endl;
 
-      deallog << fe.quadrature_point(q_point) << " ";
+      deallog << fe.quadrature_point(q_point) << ' ';
 
       for (unsigned int i = 0; i < fe_rt.dofs_per_cell; ++i)
         for (unsigned int c = 0; c < fe.get_fe().n_components(); ++c)
-          deallog << " " << fe.shape_value_component(i, q_point, c);
+          deallog << ' ' << fe.shape_value_component(i, q_point, c);
 
       deallog << std::endl;
     }
diff --git a/tests/fe/rt_bubbles_1.cc b/tests/fe/rt_bubbles_1.cc
index 24dac0676e..21b0edfb2e 100644
--- a/tests/fe/rt_bubbles_1.cc
+++ b/tests/fe/rt_bubbles_1.cc
@@ -59,7 +59,7 @@ plot_shape_functions(const unsigned int degree)
             for (unsigned int i = 0; i < fe_rt_bubbles.dofs_per_cell; ++i)
               {
                 for (unsigned int c = 0; c < dim; ++c)
-                  deallog << " "
+                  deallog << ' '
                           << fe_rt_bubbles.shape_value_component(i, p, c);
                 deallog << "  ";
               }
diff --git a/tests/fe/rt_bubbles_16.cc b/tests/fe/rt_bubbles_16.cc
index e6e6bf8b7b..df289140e3 100644
--- a/tests/fe/rt_bubbles_16.cc
+++ b/tests/fe/rt_bubbles_16.cc
@@ -38,7 +38,7 @@ test(const unsigned int degree)
           << ", restriction is additive flags:" << std::endl;
 
   for (unsigned int i = 0; i < fe_rt_bubbles.dofs_per_cell; ++i)
-    deallog << fe_rt_bubbles.restriction_is_additive(i) << " ";
+    deallog << fe_rt_bubbles.restriction_is_additive(i) << ' ';
 
   deallog << std::endl;
 }
diff --git a/tests/fe/rt_bubbles_3.cc b/tests/fe/rt_bubbles_3.cc
index 1cec8b1035..712a4fdfe7 100644
--- a/tests/fe/rt_bubbles_3.cc
+++ b/tests/fe/rt_bubbles_3.cc
@@ -30,7 +30,7 @@ template <int dim>
 void
 test(const unsigned int degree)
 {
-  deallog << "FE_RT_Bubbles<" << dim << "> (" << degree << ")" << std::endl;
+  deallog << "FE_RT_Bubbles<" << dim << "> (" << degree << ')' << std::endl;
 
   FE_RT_Bubbles<dim>        fe_rt_bubbles(degree);
   const FullMatrix<double> &constraints = fe_rt_bubbles.constraints();
diff --git a/tests/fe/rtn_2.cc b/tests/fe/rtn_2.cc
index 1ac4b3c225..e4e2a543e9 100644
--- a/tests/fe/rtn_2.cc
+++ b/tests/fe/rtn_2.cc
@@ -65,11 +65,11 @@ plot_shape_functions(const unsigned int degree)
       if (q_point % QIterated<1>(q_trapez, div).size() == 0)
         deallog << std::endl;
 
-      deallog << fe.quadrature_point(q_point) << " ";
+      deallog << fe.quadrature_point(q_point) << ' ';
 
       for (unsigned int i = 0; i < fe_rt.dofs_per_cell; ++i)
         for (unsigned int c = 0; c < fe.get_fe().n_components(); ++c)
-          deallog << " " << fe.shape_value_component(i, q_point, c);
+          deallog << ' ' << fe.shape_value_component(i, q_point, c);
 
       deallog << std::endl;
     }
diff --git a/tests/feinterface/fe_interface_values_01.cc b/tests/feinterface/fe_interface_values_01.cc
index fef684011f..db7f585635 100644
--- a/tests/feinterface/fe_interface_values_01.cc
+++ b/tests/feinterface/fe_interface_values_01.cc
@@ -46,7 +46,7 @@ inspect_fiv(FEInterfaceValues<dim> &fiv)
 
   deallog << "interface_dof_indices: ";
   for (auto i : indices)
-    deallog << i << " ";
+    deallog << i << ' ';
   deallog << "\n";
 
 
@@ -146,7 +146,7 @@ test()
             mycell->get_dof_indices(indices);
             deallog << "cell " << c << ": ";
             for (auto i : indices)
-              deallog << i << " ";
+              deallog << i << ' ';
             deallog << "\n";
             ++mycell;
           }
diff --git a/tests/feinterface/fe_interface_values_05.cc b/tests/feinterface/fe_interface_values_05.cc
index 82b322cf39..222d0ec528 100644
--- a/tests/feinterface/fe_interface_values_05.cc
+++ b/tests/feinterface/fe_interface_values_05.cc
@@ -46,7 +46,7 @@ inspect_fiv(FEInterfaceValues<dim> &fiv)
 
   deallog << "interface_dof_indices: ";
   for (auto i : indices)
-    deallog << i << " ";
+    deallog << i << ' ';
   deallog << "\n";
 
 
@@ -144,7 +144,7 @@ test()
             mycell->get_dof_indices(indices);
             deallog << "cell " << c << ": ";
             for (auto i : indices)
-              deallog << i << " ";
+              deallog << i << ' ';
             deallog << "\n";
             ++mycell;
           }
diff --git a/tests/feinterface/multigrid_01.cc b/tests/feinterface/multigrid_01.cc
index c22dff4107..edb63ac00f 100644
--- a/tests/feinterface/multigrid_01.cc
+++ b/tests/feinterface/multigrid_01.cc
@@ -46,7 +46,7 @@ inspect_fiv(FEInterfaceValues<dim> &fiv)
 
   deallog << "interface_dof_indices: ";
   for (auto i : indices)
-    deallog << i << " ";
+    deallog << i << ' ';
   deallog << "\n";
 
 
@@ -146,7 +146,7 @@ test()
             mycell->get_mg_dof_indices(indices);
             deallog << "cell " << c << ": ";
             for (auto i : indices)
-              deallog << i << " ";
+              deallog << i << ' ';
             deallog << "\n";
             ++mycell;
           }
@@ -183,7 +183,7 @@ test()
             mycell->get_mg_dof_indices(indices);
             deallog << "cell " << c << ": ";
             for (auto i : indices)
-              deallog << i << " ";
+              deallog << i << ' ';
             deallog << "\n";
             mycell = cell->neighbor(f);
           }
diff --git a/tests/feinterface/step-12.cc b/tests/feinterface/step-12.cc
index badfc44fe9..e6945445d8 100644
--- a/tests/feinterface/step-12.cc
+++ b/tests/feinterface/step-12.cc
@@ -456,7 +456,7 @@ namespace Step12
   AdvectionProblem<dim>::output_results(const unsigned int cycle) const
   {
     const std::string filename = "solution-" + std::to_string(cycle) + ".vtk";
-    deallog << "Writing solution to <" << filename << ">" << std::endl;
+    deallog << "Writing solution to <" << filename << '>' << std::endl;
     std::ofstream output(filename);
 
     DataOut<dim> data_out;
diff --git a/tests/full_matrix/full_matrix_move.cc b/tests/full_matrix/full_matrix_move.cc
index b912ef280f..eecd24ff80 100644
--- a/tests/full_matrix/full_matrix_move.cc
+++ b/tests/full_matrix/full_matrix_move.cc
@@ -31,16 +31,16 @@ main()
     for (std::size_t j = 0; j < n; ++j)
       A(i, j) = n * i + j;
 
-  deallog << "Size of A:" << std::endl << A.m() << " " << A.n() << std::endl;
+  deallog << "Size of A:" << std::endl << A.m() << ' ' << A.n() << std::endl;
 
   FullMatrix<double> B = std::move(A);
 
-  deallog << "Size of B:" << std::endl << B.m() << " " << B.n() << std::endl;
-  deallog << "Size of A:" << std::endl << A.m() << " " << A.n() << std::endl;
+  deallog << "Size of B:" << std::endl << B.m() << ' ' << B.n() << std::endl;
+  deallog << "Size of A:" << std::endl << A.m() << ' ' << A.n() << std::endl;
 
   A = std::move(B);
-  deallog << "Size of B:" << std::endl << B.m() << " " << B.n() << std::endl;
-  deallog << "Size of A:" << std::endl << A.m() << " " << A.n() << std::endl;
+  deallog << "Size of B:" << std::endl << B.m() << ' ' << B.n() << std::endl;
+  deallog << "Size of A:" << std::endl << A.m() << ' ' << A.n() << std::endl;
 
   return 0;
 }
diff --git a/tests/fullydistributed_grids/copy_serial_tria_06.cc b/tests/fullydistributed_grids/copy_serial_tria_06.cc
index b38a7028d8..27ca4dd312 100644
--- a/tests/fullydistributed_grids/copy_serial_tria_06.cc
+++ b/tests/fullydistributed_grids/copy_serial_tria_06.cc
@@ -77,7 +77,7 @@ test(int n_refinements, MPI_Comm comm)
 
           deallog << std::setw(4) << cell->subdomain_id() << " : ";
           for (const auto dof : dofs)
-            deallog << std::setw(4) << dof << " ";
+            deallog << std::setw(4) << dof << ' ';
           deallog << std::endl;
         }
   }
diff --git a/tests/fullydistributed_grids/repartitioning_07.cc b/tests/fullydistributed_grids/repartitioning_07.cc
index 091107ad7e..be15c1f9df 100644
--- a/tests/fullydistributed_grids/repartitioning_07.cc
+++ b/tests/fullydistributed_grids/repartitioning_07.cc
@@ -76,7 +76,7 @@ test(const MPI_Comm comm)
   parallel::fullydistributed::Triangulation<dim> tria_pft(comm);
   tria_pft.create_triangulation(construction_data);
 
-  deallog << tria.n_locally_owned_active_cells() << " "
+  deallog << tria.n_locally_owned_active_cells() << ' '
           << tria_pft.n_locally_owned_active_cells() << std::endl;
 }
 
diff --git a/tests/gla/block_mat_03.cc b/tests/gla/block_mat_03.cc
index 3b10cfb059..a7d968c851 100644
--- a/tests/gla/block_mat_03.cc
+++ b/tests/gla/block_mat_03.cc
@@ -76,7 +76,7 @@ test()
   const std::vector<types::global_dof_index> dofs_per_block =
     DoFTools::count_dofs_per_fe_block(dof_handler, sub_blocks);
 
-  deallog << "size: " << dofs_per_block[0] << " " << dofs_per_block[1]
+  deallog << "size: " << dofs_per_block[0] << ' ' << dofs_per_block[1]
           << std::endl;
 
   std::vector<IndexSet> locally_relevant_partitioning;
@@ -181,7 +181,7 @@ test_alt()
   const std::vector<types::global_dof_index> dofs_per_block =
     DoFTools::count_dofs_per_fe_block(dof_handler, sub_blocks);
 
-  deallog << "size: " << dofs_per_block[0] << " " << dofs_per_block[1]
+  deallog << "size: " << dofs_per_block[0] << ' ' << dofs_per_block[1]
           << std::endl;
 
   std::vector<IndexSet> locally_relevant_partitioning;
diff --git a/tests/gla/vec_01.cc b/tests/gla/vec_01.cc
index 46dfbb3d46..626f995ef7 100644
--- a/tests/gla/vec_01.cc
+++ b/tests/gla/vec_01.cc
@@ -66,9 +66,9 @@ test()
   // check local values
   if (myid == 0)
     {
-      deallog << myid * 2 << ":" << get_real_assert_zero_imag(v(myid * 2))
+      deallog << myid * 2 << ':' << get_real_assert_zero_imag(v(myid * 2))
               << std::endl;
-      deallog << myid * 2 + 1 << ":"
+      deallog << myid * 2 + 1 << ':'
               << get_real_assert_zero_imag(v(myid * 2 + 1)) << std::endl;
     }
 
diff --git a/tests/gla/vec_02.cc b/tests/gla/vec_02.cc
index 1dcc9ce61b..fcbaabcea3 100644
--- a/tests/gla/vec_02.cc
+++ b/tests/gla/vec_02.cc
@@ -70,9 +70,9 @@ test()
   // check local values
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
     {
-      deallog << myid * 2 << ":" << get_real_assert_zero_imag(v(myid * 2))
+      deallog << myid * 2 << ':' << get_real_assert_zero_imag(v(myid * 2))
               << std::endl;
-      deallog << myid * 2 + 1 << ":"
+      deallog << myid * 2 + 1 << ':'
               << get_real_assert_zero_imag(v(myid * 2 + 1)) << std::endl;
     }
 
diff --git a/tests/gmsh/gmsh_api_02.cc b/tests/gmsh/gmsh_api_02.cc
index a78fcd5385..b18d96f75e 100644
--- a/tests/gmsh/gmsh_api_02.cc
+++ b/tests/gmsh/gmsh_api_02.cc
@@ -25,8 +25,8 @@ template <int dim, int spacedim>
 void
 test(const std::uint8_t kind, const std::string out = "")
 {
-  deallog << "Testing kind(" << (int)kind << ") in dimensions "
-          << "<" << dim << "," << spacedim << ">" << std::endl;
+  deallog << "Testing kind(" << (int)kind << ") in dimensions " << '<' << dim
+          << ',' << spacedim << '>' << std::endl;
 
   Triangulation<dim, spacedim> tria;
   GridGenerator::reference_cell(
diff --git a/tests/gmsh/gmsh_api_04.cc b/tests/gmsh/gmsh_api_04.cc
index ba753b3a5d..f06f7b5280 100644
--- a/tests/gmsh/gmsh_api_04.cc
+++ b/tests/gmsh/gmsh_api_04.cc
@@ -27,8 +27,8 @@ template <int dim, int spacedim>
 void
 test(const std::uint8_t kind, const std::string out = "")
 {
-  deallog << "Testing kind(" << (int)kind << ") in dimensions "
-          << "<" << dim << "," << spacedim << ">" << std::endl;
+  deallog << "Testing kind(" << (int)kind << ") in dimensions " << '<' << dim
+          << ',' << spacedim << '>' << std::endl;
 
   Triangulation<dim, spacedim> tria;
   GridGenerator::reference_cell(
diff --git a/tests/grid/cell_id_01.cc b/tests/grid/cell_id_01.cc
index 56e47d5a93..9eb0485f39 100644
--- a/tests/grid/cell_id_01.cc
+++ b/tests/grid/cell_id_01.cc
@@ -42,8 +42,8 @@ check(TRIA &tr)
 
   for (; cell != endc; ++cell)
     {
-      deallog << cell->level() << " " << cell->index() << " " << cell->id()
-              << " " << cell->id().to_string() << std::endl;
+      deallog << cell->level() << ' ' << cell->index() << ' ' << cell->id()
+              << ' ' << cell->id().to_string() << std::endl;
     }
 
   deallog << "OK" << std::endl;
diff --git a/tests/grid/cell_id_02.cc b/tests/grid/cell_id_02.cc
index 206d9e3be3..22fcdb8820 100644
--- a/tests/grid/cell_id_02.cc
+++ b/tests/grid/cell_id_02.cc
@@ -48,8 +48,8 @@ check(TRIA &tr)
       CellId             tmp;
       std::istringstream in(outb.str());
       in >> tmp;
-      deallog << cell->level() << " " << cell->index() << " " << cell->id()
-              << " " << tmp << std::endl;
+      deallog << cell->level() << ' ' << cell->index() << ' ' << cell->id()
+              << ' ' << tmp << std::endl;
     }
 
 
diff --git a/tests/grid/cell_id_03.cc b/tests/grid/cell_id_03.cc
index f85f718b61..d623718d20 100644
--- a/tests/grid/cell_id_03.cc
+++ b/tests/grid/cell_id_03.cc
@@ -43,7 +43,7 @@ check(TRIA &tr)
 
   for (; cell != endc; ++cell)
     {
-      deallog << cell->level() << " " << cell->index() << std::endl;
+      deallog << cell->level() << ' ' << cell->index() << std::endl;
 
       // Store the CellId and create a cell iterator pointing to the same cell
 
@@ -51,7 +51,7 @@ check(TRIA &tr)
 
       typename TRIA::cell_iterator cell2 = tr.create_cell_iterator(cid);
 
-      deallog << cell2->level() << " " << cell2->index() << std::endl;
+      deallog << cell2->level() << ' ' << cell2->index() << std::endl;
     }
 
   deallog << "OK" << std::endl;
diff --git a/tests/grid/cell_id_04.cc b/tests/grid/cell_id_04.cc
index d66c42ccad..dd5c926006 100644
--- a/tests/grid/cell_id_04.cc
+++ b/tests/grid/cell_id_04.cc
@@ -44,7 +44,7 @@ check(Triangulation<dim> &tr)
 
   for (; cell != endc; ++cell)
     {
-      deallog << cell->level() << " " << cell->index() << std::endl;
+      deallog << cell->level() << ' ' << cell->index() << std::endl;
 
       // Store the CellId, convert it to a binary representation,
       // create a new CellId from that, and create a cell iterator
@@ -62,7 +62,7 @@ check(Triangulation<dim> &tr)
       Assert(cid2 == cid, ExcInternalError());
       Assert(cell2 == cell, ExcInternalError());
 
-      deallog << cell2->level() << " " << cell2->index() << std::endl;
+      deallog << cell2->level() << ' ' << cell2->index() << std::endl;
     }
 
   deallog << "OK" << std::endl;
diff --git a/tests/grid/cell_id_06.cc b/tests/grid/cell_id_06.cc
index 7b6d0e345a..3124ff7705 100644
--- a/tests/grid/cell_id_06.cc
+++ b/tests/grid/cell_id_06.cc
@@ -42,6 +42,6 @@ main()
          {id0, id3}, // grand child (false, true)
          {id0, id4}} // cell with different coarse-cell id (false, false)
   )
-    deallog << pair.first.is_parent_of(pair.second) << " "
+    deallog << pair.first.is_parent_of(pair.second) << ' '
             << pair.first.is_ancestor_of(pair.second) << std::endl;
 }
diff --git a/tests/grid/cell_measure_01.cc b/tests/grid/cell_measure_01.cc
index 1d38e83bb7..9f0c1305d2 100644
--- a/tests/grid/cell_measure_01.cc
+++ b/tests/grid/cell_measure_01.cc
@@ -38,7 +38,7 @@ test<1>()
   unsigned int indices1[GeometryInfo<1>::vertices_per_cell] = {0, 1};
   std::vector<unsigned int> indices2                        = {0, 1};
 
-  deallog << "1d: " << GridTools::cell_measure(points, indices1) << " "
+  deallog << "1d: " << GridTools::cell_measure(points, indices1) << ' '
           << GridTools::cell_measure(points, indices2) << std::endl;
 }
 
@@ -55,7 +55,7 @@ test<2>()
   unsigned int indices1[GeometryInfo<2>::vertices_per_cell] = {0, 1, 2, 3};
   std::vector<unsigned int> indices2                        = {0, 1, 2, 3};
 
-  deallog << "2d: " << GridTools::cell_measure(points, indices1) << " "
+  deallog << "2d: " << GridTools::cell_measure(points, indices1) << ' '
           << GridTools::cell_measure(points, indices2) << std::endl;
 }
 
@@ -77,7 +77,7 @@ test<3>()
     0, 1, 2, 3, 4, 5, 6, 7};
   std::vector<unsigned int> indices2 = {0, 1, 2, 3, 4, 5, 6, 7};
 
-  deallog << "3d: " << GridTools::cell_measure(points, indices1) << " "
+  deallog << "3d: " << GridTools::cell_measure(points, indices1) << ' '
           << GridTools::cell_measure(points, indices2) << std::endl;
 }
 
diff --git a/tests/grid/flatten_grid_01.cc b/tests/grid/flatten_grid_01.cc
index 3c91d0fa2f..d582116cef 100644
--- a/tests/grid/flatten_grid_01.cc
+++ b/tests/grid/flatten_grid_01.cc
@@ -25,8 +25,8 @@ template <int dim, int spacedim1, int spacedim2>
 void
 test()
 {
-  deallog << "Testing <" << dim << "," << spacedim1 << "> VS <" << dim << ","
-          << spacedim2 << ">" << std::endl;
+  deallog << "Testing <" << dim << ',' << spacedim1 << "> VS <" << dim << ','
+          << spacedim2 << '>' << std::endl;
 
   Triangulation<dim, spacedim1> tria1;
   GridGenerator::hyper_cube(tria1);
diff --git a/tests/grid/get_dof_to_support_patch_map_01.cc b/tests/grid/get_dof_to_support_patch_map_01.cc
index 02b0166b8c..105eb55b1e 100644
--- a/tests/grid/get_dof_to_support_patch_map_01.cc
+++ b/tests/grid/get_dof_to_support_patch_map_01.cc
@@ -157,7 +157,7 @@ test()
               typename dealii::DoFHandler<dim>::active_cell_iterator
                          patch_cell = *(patch_iter);
               Point<dim> cell_bary  = patch_cell->barycenter();
-              deallog << "(";
+              deallog << '(';
               for (unsigned int d = 0; d < dim - 1; ++d)
                 deallog << cell_bary[d] << ", ";
               deallog << cell_bary[dim - 1] << ") ";
diff --git a/tests/grid/global_ids_01.cc b/tests/grid/global_ids_01.cc
index c08d1d38fb..512620b8df 100644
--- a/tests/grid/global_ids_01.cc
+++ b/tests/grid/global_ids_01.cc
@@ -42,7 +42,7 @@ test(int n_refinements, MPI_Comm comm)
 
   for (const auto cell : tria.active_cell_iterators())
     if (!cell->is_artificial())
-      deallog << cell->id() << " -> " << cell->subdomain_id() << " "
+      deallog << cell->id() << " -> " << cell->subdomain_id() << ' '
               << cell->global_active_cell_index() << std::endl;
 
   const Utilities::MPI::Partitioner &part =
diff --git a/tests/grid/global_ids_03.cc b/tests/grid/global_ids_03.cc
index 4a8d1b45f3..ae3dace776 100644
--- a/tests/grid/global_ids_03.cc
+++ b/tests/grid/global_ids_03.cc
@@ -49,7 +49,7 @@ test(int n_refinements, MPI_Comm comm)
       for (const auto cell : tria.cell_iterators_on_level(l))
         if (cell->level_subdomain_id() !=
             dealii::numbers::artificial_subdomain_id)
-          deallog << cell->id() << " -> " << cell->level_subdomain_id() << " "
+          deallog << cell->id() << " -> " << cell->level_subdomain_id() << ' '
                   << cell->global_level_cell_index() << std::endl;
 
       const Utilities::MPI::Partitioner &part =
diff --git a/tests/grid/grid_generator_airfoil_01.cc b/tests/grid/grid_generator_airfoil_01.cc
index 128209273b..f9ccdc4652 100644
--- a/tests/grid/grid_generator_airfoil_01.cc
+++ b/tests/grid/grid_generator_airfoil_01.cc
@@ -34,15 +34,15 @@ print_triangulation(const Triangulation<dim, dim> &tria)
 {
   for (const auto &cell : tria)
     {
-      deallog << cell.material_id() << " ";
+      deallog << cell.material_id() << ' ';
 
       for (const unsigned int f : GeometryInfo<dim>::face_indices())
         deallog << (cell.face(f)->at_boundary() ? cell.face(f)->boundary_id() :
                                                   -1)
-                << " ";
+                << ' ';
 
       for (const unsigned int v : GeometryInfo<dim>::vertex_indices())
-        deallog << cell.vertex(v) << " ";
+        deallog << cell.vertex(v) << ' ';
 
       deallog << std::endl;
     }
diff --git a/tests/grid/grid_generator_from_name_and_argument_01.cc b/tests/grid/grid_generator_from_name_and_argument_01.cc
index 7897001cf9..03e8ba72ec 100644
--- a/tests/grid/grid_generator_from_name_and_argument_01.cc
+++ b/tests/grid/grid_generator_from_name_and_argument_01.cc
@@ -30,7 +30,7 @@ test(const std::string &name, const std::string &arguments)
   Triangulation<dim, spacedim> tria;
 
   deallog << "Generating Triangulation<" << dim << ", " << spacedim
-          << "> : " << name << "(" << arguments << ")" << std::endl;
+          << "> : " << name << '(' << arguments << ')' << std::endl;
 
   GridGenerator::generate_from_name_and_arguments(tria, name, arguments);
 
diff --git a/tests/grid/grid_generator_non_standard_orientation_mesh_2d.cc b/tests/grid/grid_generator_non_standard_orientation_mesh_2d.cc
index 4528da7a69..e5010c0474 100644
--- a/tests/grid/grid_generator_non_standard_orientation_mesh_2d.cc
+++ b/tests/grid/grid_generator_non_standard_orientation_mesh_2d.cc
@@ -61,7 +61,7 @@ plot_all_info(const Triangulation<dim> &tria)
         {
           deallog << cell->line_orientation(line_index) << "  ";
         } // line_index
-      deallog << "}" << std::endl << std::endl;
+      deallog << '}' << std::endl << std::endl;
     } // cell
 }
 
diff --git a/tests/grid/grid_generator_non_standard_orientation_mesh_3d.cc b/tests/grid/grid_generator_non_standard_orientation_mesh_3d.cc
index 89145825d0..1c303626f1 100644
--- a/tests/grid/grid_generator_non_standard_orientation_mesh_3d.cc
+++ b/tests/grid/grid_generator_non_standard_orientation_mesh_3d.cc
@@ -63,7 +63,7 @@ plot_all_info(const Triangulation<dim> &tria)
         {
           deallog << cell->line_orientation(line_index) << "  ";
         } // line_index
-      deallog << "}" << std::endl << std::endl;
+      deallog << '}' << std::endl << std::endl;
     } // cell
 }
 
diff --git a/tests/grid/grid_out_in_vtk_01.cc b/tests/grid/grid_out_in_vtk_01.cc
index 19456e863b..8e4fb1dde6 100644
--- a/tests/grid/grid_out_in_vtk_01.cc
+++ b/tests/grid/grid_out_in_vtk_01.cc
@@ -46,7 +46,7 @@ check(Triangulation<dim, spacedim> &tria)
   gi.attach_triangulation(tria2);
   gi.read_vtk(infile);
 
-  deallog << "Testing Triangulation<" << dim << "," << spacedim << ">"
+  deallog << "Testing Triangulation<" << dim << ',' << spacedim << '>'
           << std::endl;
   AssertDimension(tria.n_vertices(), tria2.n_vertices());
   AssertDimension(tria.n_active_cells(), tria2.n_active_cells());
diff --git a/tests/grid/grid_out_vtk_02.cc b/tests/grid/grid_out_vtk_02.cc
index edd4faf1ba..d7444e5ebd 100644
--- a/tests/grid/grid_out_vtk_02.cc
+++ b/tests/grid/grid_out_vtk_02.cc
@@ -89,7 +89,7 @@ test()
                 if (cell->level_subdomain_id() != 4294967294)
                   deallog << cell->level_subdomain_id();
                 else
-                  deallog << "-";
+                  deallog << '-';
               deallog << std::endl;
             }
           deallog << std::endl;
diff --git a/tests/grid/grid_parallelepiped_04.cc b/tests/grid/grid_parallelepiped_04.cc
index e924a4f02a..9b094dad68 100644
--- a/tests/grid/grid_parallelepiped_04.cc
+++ b/tests/grid/grid_parallelepiped_04.cc
@@ -47,7 +47,7 @@ check_parallelepiped(bool colorize, bool log, const unsigned int (&subd)[dim])
 {
   deallog << "* checking dim=" << dim << " subd=";
   for (unsigned int i = 0; i < dim; ++i)
-    deallog << subd[i] << " ";
+    deallog << subd[i] << ' ';
   deallog << std::endl;
 
   // Data structure defining dim coordinates that make up a
@@ -109,7 +109,7 @@ check_parallelepiped(bool colorize, bool log, const unsigned int (&subd)[dim])
          it != boundary_count.end();
          ++it)
       {
-        deallog << it->first << "(" << it->second << " times) ";
+        deallog << it->first << '(' << it->second << " times) ";
       }
     deallog << std::endl;
   }
diff --git a/tests/grid/grid_tools_active_cell_layer_within_distance_01.cc b/tests/grid/grid_tools_active_cell_layer_within_distance_01.cc
index e95cd296e2..6aa78ea26f 100644
--- a/tests/grid/grid_tools_active_cell_layer_within_distance_01.cc
+++ b/tests/grid/grid_tools_active_cell_layer_within_distance_01.cc
@@ -43,7 +43,7 @@ write_mat_id_to_file(const Triangulation<dim> &tria)
                                                     endc  = tria.end();
   for (; cell != endc; ++cell, ++count)
     {
-      deallog << count << " " << static_cast<int>(cell->material_id())
+      deallog << count << ' ' << static_cast<int>(cell->material_id())
               << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/grid/grid_tools_active_cell_layer_within_distance_02.cc b/tests/grid/grid_tools_active_cell_layer_within_distance_02.cc
index fa7d4b6688..8b0853b2a7 100644
--- a/tests/grid/grid_tools_active_cell_layer_within_distance_02.cc
+++ b/tests/grid/grid_tools_active_cell_layer_within_distance_02.cc
@@ -50,7 +50,7 @@ write_mat_id_to_file(const Triangulation<dim> &tria)
                                                     endc  = tria.end();
   for (; cell != endc; ++cell, ++count)
     {
-      deallog << count << " " << static_cast<int>(cell->material_id())
+      deallog << count << ' ' << static_cast<int>(cell->material_id())
               << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/grid/grid_tools_bounding_box_01.cc b/tests/grid/grid_tools_bounding_box_01.cc
index 2e65cba11a..c59c136ec9 100644
--- a/tests/grid/grid_tools_bounding_box_01.cc
+++ b/tests/grid/grid_tools_bounding_box_01.cc
@@ -65,7 +65,7 @@ test()
   auto bounding_box =
     GridTools::compute_bounding_box(tria, predicate); // General predicate
 
-  deallog << bounding_box.first << " " << bounding_box.second << std::endl;
+  deallog << bounding_box.first << ' ' << bounding_box.second << std::endl;
 }
 
 
diff --git a/tests/grid/grid_tools_bounding_box_02.cc b/tests/grid/grid_tools_bounding_box_02.cc
index fb1abdc67b..177b50edd7 100644
--- a/tests/grid/grid_tools_bounding_box_02.cc
+++ b/tests/grid/grid_tools_bounding_box_02.cc
@@ -69,7 +69,7 @@ test()
   BoundingBox<dim> bounding_box =
     GridTools::compute_bounding_box(tria, predicate); // General predicate
 
-  deallog << bounding_box.get_boundary_points().first << " "
+  deallog << bounding_box.get_boundary_points().first << ' '
           << bounding_box.get_boundary_points().second << std::endl;
 }
 
diff --git a/tests/grid/grid_tools_halo_layer_01.cc b/tests/grid/grid_tools_halo_layer_01.cc
index bc2c056511..02d8b18499 100644
--- a/tests/grid/grid_tools_halo_layer_01.cc
+++ b/tests/grid/grid_tools_halo_layer_01.cc
@@ -38,7 +38,7 @@ write_mat_id_to_file(const Triangulation<dim> &tria)
                                                     endc  = tria.end();
   for (; cell != endc; ++cell, ++count)
     {
-      deallog << count << " " << static_cast<int>(cell->material_id())
+      deallog << count << ' ' << static_cast<int>(cell->material_id())
               << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/grid/grid_tools_halo_layer_02.cc b/tests/grid/grid_tools_halo_layer_02.cc
index a1e44d93b1..852b94e070 100644
--- a/tests/grid/grid_tools_halo_layer_02.cc
+++ b/tests/grid/grid_tools_halo_layer_02.cc
@@ -32,7 +32,7 @@ write_mat_id_to_file(const Triangulation<dim> &tria)
                                                     endc  = tria.end();
   for (; cell != endc; ++cell, ++count)
     {
-      deallog << count << " " << static_cast<int>(cell->material_id())
+      deallog << count << ' ' << static_cast<int>(cell->material_id())
               << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/grid/grid_tools_halo_layer_03.cc b/tests/grid/grid_tools_halo_layer_03.cc
index 662b2fae8b..7e72eaf35b 100644
--- a/tests/grid/grid_tools_halo_layer_03.cc
+++ b/tests/grid/grid_tools_halo_layer_03.cc
@@ -32,7 +32,7 @@ write_mat_id_to_file(const Triangulation<dim> &tria)
                                                     endc  = tria.end();
   for (; cell != endc; ++cell, ++count)
     {
-      deallog << count << " " << static_cast<int>(cell->material_id())
+      deallog << count << ' ' << static_cast<int>(cell->material_id())
               << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/grid/grid_tools_halo_layer_04.cc b/tests/grid/grid_tools_halo_layer_04.cc
index 04a581e753..d8b17939db 100644
--- a/tests/grid/grid_tools_halo_layer_04.cc
+++ b/tests/grid/grid_tools_halo_layer_04.cc
@@ -36,7 +36,7 @@ write_active_fe_index_to_file(const DoFHandler<dim> &dof_handler)
                                                  endc = dof_handler.end();
   for (; cell != endc; ++cell, ++count)
     {
-      deallog << count << " " << cell->active_fe_index() << std::endl;
+      deallog << count << ' ' << cell->active_fe_index() << std::endl;
     }
   deallog << std::endl;
 }
diff --git a/tests/grid/grid_tools_halo_layer_05.cc b/tests/grid/grid_tools_halo_layer_05.cc
index 2cfe1acaa4..5ddbce5b42 100644
--- a/tests/grid/grid_tools_halo_layer_05.cc
+++ b/tests/grid/grid_tools_halo_layer_05.cc
@@ -36,7 +36,7 @@ write_active_fe_index_to_file(const DoFHandler<dim> &dof_handler)
                                                  endc = dof_handler.end();
   for (; cell != endc; ++cell, ++count)
     {
-      deallog << count << " " << cell->active_fe_index() << std::endl;
+      deallog << count << ' ' << cell->active_fe_index() << std::endl;
     }
   deallog << std::endl;
 }
diff --git a/tests/grid/grid_tools_halo_layer_ghost_cells.cc b/tests/grid/grid_tools_halo_layer_ghost_cells.cc
index 651d0f652d..3bef60877a 100644
--- a/tests/grid/grid_tools_halo_layer_ghost_cells.cc
+++ b/tests/grid/grid_tools_halo_layer_ghost_cells.cc
@@ -79,12 +79,11 @@ test()
                           ExcMessage("Cell is not a ghost cell!"));
               AssertThrow(cell_2->is_ghost() == true,
                           ExcMessage("Halo cell is not a ghost cell!"));
-              deallog << "Ghost " << cell_1->level() << " " << cell_1->index()
-                      << " " << cell_1->id() << " " << cell_1->id().to_string()
-                      << " "
-                      << "Halo " << cell_2->level() << " " << cell_2->index()
-                      << " " << cell_2->id() << " " << cell_2->id().to_string()
-                      << std::endl;
+              deallog << "Ghost " << cell_1->level() << ' ' << cell_1->index()
+                      << ' ' << cell_1->id() << ' ' << cell_1->id().to_string()
+                      << ' ' << "Halo " << cell_2->level() << ' '
+                      << cell_2->index() << ' ' << cell_2->id() << ' '
+                      << cell_2->id().to_string() << std::endl;
               AssertThrow(cell_2 == cell_1,
                           ExcMessage(
                             "Halo cell is not identical to ghost cell."));
diff --git a/tests/grid/merge_triangulations_02.cc b/tests/grid/merge_triangulations_02.cc
index 3cd3707cd7..f94b83f497 100644
--- a/tests/grid/merge_triangulations_02.cc
+++ b/tests/grid/merge_triangulations_02.cc
@@ -59,7 +59,7 @@ mesh_info(const Triangulation<dim> &tria)
          it != boundary_count.end();
          ++it)
       {
-        deallog << it->first << "(" << it->second << " times) ";
+        deallog << it->first << '(' << it->second << " times) ";
       }
     deallog << std::endl;
   }
diff --git a/tests/grid/merge_triangulations_03.cc b/tests/grid/merge_triangulations_03.cc
index d297173a34..72250bdff7 100644
--- a/tests/grid/merge_triangulations_03.cc
+++ b/tests/grid/merge_triangulations_03.cc
@@ -82,7 +82,7 @@ template <int dim>
 void
 mesh_info(const Triangulation<dim> &tria, const std::string &filename)
 {
-  deallog << "Mesh info for " << filename << ":" << std::endl
+  deallog << "Mesh info for " << filename << ':' << std::endl
           << " dimension: " << dim << std::endl
           << " no. of cells: " << tria.n_active_cells() << std::endl;
 
@@ -105,7 +105,7 @@ mesh_info(const Triangulation<dim> &tria, const std::string &filename)
          it != boundary_count.end();
          ++it)
       {
-        deallog << it->first << "(" << it->second << " times) ";
+        deallog << it->first << '(' << it->second << " times) ";
       }
     deallog << std::endl;
   }
diff --git a/tests/grid/number_cache_01.cc b/tests/grid/number_cache_01.cc
index f23717342a..67b8e4b738 100644
--- a/tests/grid/number_cache_01.cc
+++ b/tests/grid/number_cache_01.cc
@@ -74,7 +74,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "d" << std::endl;
+  deallog << dim << 'd' << std::endl;
 
   Triangulation<dim> tria;
   GridGenerator::hyper_cube(tria);
diff --git a/tests/grid/number_cache_03.cc b/tests/grid/number_cache_03.cc
index fe5a2ee213..df91cac9ba 100644
--- a/tests/grid/number_cache_03.cc
+++ b/tests/grid/number_cache_03.cc
@@ -79,7 +79,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "d" << std::endl;
+  deallog << dim << 'd' << std::endl;
 
   Triangulation<dim> tria;
   GridGenerator::hyper_cube(tria);
diff --git a/tests/grid/partition_triangulation_zorder_01.cc b/tests/grid/partition_triangulation_zorder_01.cc
index fd9a926352..8a1f7f9444 100644
--- a/tests/grid/partition_triangulation_zorder_01.cc
+++ b/tests/grid/partition_triangulation_zorder_01.cc
@@ -36,7 +36,7 @@ test(const int n_refinements, const int n_partitions, const bool blocked)
   GridTools::partition_triangulation_zorder(n_partitions, tria, blocked);
 
   for (const auto &cell : tria.active_cell_iterators())
-    deallog << cell->subdomain_id() << " ";
+    deallog << cell->subdomain_id() << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/grid/periodicity_1d.cc b/tests/grid/periodicity_1d.cc
index f00e7f9742..966a0b2442 100644
--- a/tests/grid/periodicity_1d.cc
+++ b/tests/grid/periodicity_1d.cc
@@ -48,10 +48,10 @@ check()
   deallog << "Test run in " << dim << " dimensions" << std::endl;
   for (unsigned int i = 0; i < periodic_faces.size(); ++i)
     {
-      deallog << periodic_faces[i].cell[0]->index() << " "
-              << periodic_faces[i].cell[1]->index() << " "
-              << periodic_faces[i].face_idx[0] << " "
-              << periodic_faces[i].face_idx[1] << " "
+      deallog << periodic_faces[i].cell[0]->index() << ' '
+              << periodic_faces[i].cell[1]->index() << ' '
+              << periodic_faces[i].face_idx[0] << ' '
+              << periodic_faces[i].face_idx[1] << ' '
               << periodic_faces[i].orientation << std::endl;
     }
 }
diff --git a/tests/grid/real_to_unit_cell_affine_approx.cc b/tests/grid/real_to_unit_cell_affine_approx.cc
index a9e39032a5..d5c63c9713 100644
--- a/tests/grid/real_to_unit_cell_affine_approx.cc
+++ b/tests/grid/real_to_unit_cell_affine_approx.cc
@@ -46,7 +46,7 @@ do_test(const Triangulation<dim, spacedim> &tria, const Point<spacedim> &p)
           mapping_point -= cell->real_to_unit_cell_affine_approximation(p);
           deallog << "Distance to mapping point: ";
           for (unsigned int d = 0; d < dim; ++d)
-            deallog << mapping_point[d] << " ";
+            deallog << mapping_point[d] << ' ';
           deallog << std::endl;
         }
       catch (const typename Mapping<dim, spacedim>::ExcTransformationFailed &)
diff --git a/tests/grid/reference_cell_type_01.cc b/tests/grid/reference_cell_type_01.cc
index 7045228f81..5af290ede4 100644
--- a/tests/grid/reference_cell_type_01.cc
+++ b/tests/grid/reference_cell_type_01.cc
@@ -31,17 +31,17 @@ test()
   GridGenerator::subdivided_hyper_cube(tria, 3);
 
   for (const auto &cell : tria.active_cell_iterators())
-    deallog << static_cast<int>(cell->reference_cell()) << " ";
+    deallog << static_cast<int>(cell->reference_cell()) << ' ';
   deallog << std::endl;
 
   if (dim != 1)
     for (const auto &face : tria.active_face_iterators())
-      deallog << static_cast<int>(face->reference_cell()) << " ";
+      deallog << static_cast<int>(face->reference_cell()) << ' ';
   deallog << std::endl;
 
   for (const auto &cell : tria.active_cell_iterators())
     for (const auto &face : cell->face_iterators())
-      deallog << static_cast<int>(face->reference_cell()) << " ";
+      deallog << static_cast<int>(face->reference_cell()) << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/grid/refine_and_coarsen_01.cc b/tests/grid/refine_and_coarsen_01.cc
index d02ffb5a02..ce33218111 100644
--- a/tests/grid/refine_and_coarsen_01.cc
+++ b/tests/grid/refine_and_coarsen_01.cc
@@ -57,7 +57,7 @@ check()
 
   deallog << "n_active_cells: " << tria.n_active_cells() << std::endl;
 
-  deallog << "OK for " << dim << "d" << std::endl;
+  deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/grid/refinement_listener_02.cc b/tests/grid/refinement_listener_02.cc
index d82ac37e16..078e0a781c 100644
--- a/tests/grid/refinement_listener_02.cc
+++ b/tests/grid/refinement_listener_02.cc
@@ -69,7 +69,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> tria_1, tria_2;
 
diff --git a/tests/grid/refinement_listener_03.cc b/tests/grid/refinement_listener_03.cc
index 17345d588c..1032efeea1 100644
--- a/tests/grid/refinement_listener_03.cc
+++ b/tests/grid/refinement_listener_03.cc
@@ -77,7 +77,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> tria_1, tria_2;
 
diff --git a/tests/grid/torus_01.cc b/tests/grid/torus_01.cc
index ee433f21c5..36704213f7 100644
--- a/tests/grid/torus_01.cc
+++ b/tests/grid/torus_01.cc
@@ -65,7 +65,7 @@ test<3, 3>()
   deallog.get_file_stream() << "set view equal xyz" << std::endl
                             << "splot '-' w l" << std::endl;
   GridOut().write_gnuplot(triangulation, deallog.get_file_stream());
-  deallog.get_file_stream() << "e" << std::endl << "pause -1" << std::endl;
+  deallog.get_file_stream() << 'e' << std::endl << "pause -1" << std::endl;
 }
 
 
diff --git a/tests/hp/crash_15.cc b/tests/hp/crash_15.cc
index 10adf126de..31a771d486 100644
--- a/tests/hp/crash_15.cc
+++ b/tests/hp/crash_15.cc
@@ -91,7 +91,7 @@ test()
                       << cell->line(line)->nth_active_fe_index(i) << " ("
                       << fe_collection[cell->line(line)->nth_active_fe_index(i)]
                            .get_name()
-                      << ")" << std::endl;
+                      << ')' << std::endl;
 
               cell->line(line)->get_dof_indices(
                 line_dof_indices_1, cell->line(line)->nth_active_fe_index(i));
diff --git a/tests/hp/fe_face_values_reinit_01.cc b/tests/hp/fe_face_values_reinit_01.cc
index 3d4ed4a5fe..879043519b 100644
--- a/tests/hp/fe_face_values_reinit_01.cc
+++ b/tests/hp/fe_face_values_reinit_01.cc
@@ -69,7 +69,7 @@ test()
 
           for (const auto &p : hp_fe_face_values.get_present_fe_values()
                                  .get_quadrature_points())
-            deallog << p << " ";
+            deallog << p << ' ';
           deallog << std::endl;
         }
       deallog << std::endl;
@@ -83,7 +83,7 @@ test()
 
           for (const auto &p : hp_fe_face_values.get_present_fe_values()
                                  .get_quadrature_points())
-            deallog << p << " ";
+            deallog << p << ' ';
           deallog << std::endl;
         }
       deallog << std::endl;
@@ -97,7 +97,7 @@ test()
 
           for (const auto &p : hp_fe_face_values.get_present_fe_values()
                                  .get_quadrature_points())
-            deallog << p << " ";
+            deallog << p << ' ';
           deallog << std::endl;
         }
       deallog << std::endl;
@@ -111,7 +111,7 @@ test()
 
           for (const auto &p : hp_fe_face_values.get_present_fe_values()
                                  .get_quadrature_points())
-            deallog << p << " ";
+            deallog << p << ' ';
           deallog << std::endl;
         }
       deallog << std::endl;
diff --git a/tests/hp/fe_hierarchy_sequence.cc b/tests/hp/fe_hierarchy_sequence.cc
index d0922dba40..97c1a3da63 100644
--- a/tests/hp/fe_hierarchy_sequence.cc
+++ b/tests/hp/fe_hierarchy_sequence.cc
@@ -54,7 +54,7 @@ test()
 
       deallog << " idx: " << fe_index << ", sequence:";
       for (const auto index : sequence)
-        deallog << " " << index;
+        deallog << ' ' << index;
       deallog << std::endl;
     }
 }
diff --git a/tests/hp/get_interpolated_dof_values_03.cc b/tests/hp/get_interpolated_dof_values_03.cc
index 64aac02f82..b5518b2763 100644
--- a/tests/hp/get_interpolated_dof_values_03.cc
+++ b/tests/hp/get_interpolated_dof_values_03.cc
@@ -46,7 +46,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   // create a hp::DoFHandler with different finite elements on the
   // cells. note that we skip setting active_fe_indices on inactive
diff --git a/tests/hp/hp_coarsening.cc b/tests/hp/hp_coarsening.cc
index 7c54914c81..a222e64eaa 100644
--- a/tests/hp/hp_coarsening.cc
+++ b/tests/hp/hp_coarsening.cc
@@ -39,7 +39,7 @@ validate(const Triangulation<dim> &tria, const DoFHandler<dim> &dh)
 {
   deallog << "ncells: " << tria.n_global_active_cells() << " fe_indices:";
   for (const auto &cell : dh.active_cell_iterators())
-    deallog << " " << cell->active_fe_index();
+    deallog << ' ' << cell->active_fe_index();
   deallog << std::endl;
 }
 
diff --git a/tests/hp/hp_constraints_neither_dominate_01.cc b/tests/hp/hp_constraints_neither_dominate_01.cc
index 9c2b03d3a9..db6ad219ff 100644
--- a/tests/hp/hp_constraints_neither_dominate_01.cc
+++ b/tests/hp/hp_constraints_neither_dominate_01.cc
@@ -208,8 +208,8 @@ test2cells(const unsigned int p1 = 2, const unsigned int p2 = 1)
               fe_face_values.get_quadrature_points();
 
             for (unsigned int q = 0; q < n_q_points; ++q)
-              deallog << "u[" << q_points[q] << "]={" << values[q][0] << ","
-                      << values[q][1] << "}" << std::endl;
+              deallog << "u[" << q_points[q] << "]={" << values[q][0] << ','
+                      << values[q][1] << '}' << std::endl;
           }
     }
 
diff --git a/tests/hp/hp_constraints_neither_dominate_02.cc b/tests/hp/hp_constraints_neither_dominate_02.cc
index 3b792f9133..803c108f7b 100644
--- a/tests/hp/hp_constraints_neither_dominate_02.cc
+++ b/tests/hp/hp_constraints_neither_dominate_02.cc
@@ -277,11 +277,11 @@ test2cells(const FiniteElement<dim> &fe_0,
                   {
                     pairs_point_value.push_back(
                       std::make_pair(q_points[q], values[q]));
-                    //                      deallog << "@"<<q_points[q]<<" u =
+                    //                      deallog << '@'<<q_points[q]<<" u =
                     //                      {"<<values[q][0]; for (unsigned int
                     //                      c = 1; c < n_comp; c++)
-                    //                        deallog << ","<<values[q][c];
-                    //                      deallog << "}"<<std::endl;
+                    //                        deallog << ','<<values[q][c];
+                    //                      deallog << '}'<<std::endl;
                   }
               }
           }
@@ -297,10 +297,10 @@ test2cells(const FiniteElement<dim> &fe_0,
       const Vector<double> &val = pairs_point_value[p].second;
 
       Assert(val.size() == n_comp, ExcInternalError());
-      deallog << "@" << pt << " u = {" << val[0];
+      deallog << '@' << pt << " u = {" << val[0];
       for (unsigned int c = 1; c < n_comp; ++c)
-        deallog << "," << val[c];
-      deallog << "}" << std::endl;
+        deallog << ',' << val[c];
+      deallog << '}' << std::endl;
     }
 
   dof_handler.clear();
diff --git a/tests/hp/hp_q_hierarchical_constraints.cc b/tests/hp/hp_q_hierarchical_constraints.cc
index 41d8fb2fe0..1472246cb0 100644
--- a/tests/hp/hp_q_hierarchical_constraints.cc
+++ b/tests/hp/hp_q_hierarchical_constraints.cc
@@ -135,8 +135,8 @@ test(const bool apply_constrains, const unsigned int hp)
       data_out.build_patches(20);
 
       std::ostringstream filename;
-      filename << "shape_" << dim << "d"
-               << (apply_constrains ? "_constrained" : "") << hp_string << "_"
+      filename << "shape_" << dim << 'd'
+               << (apply_constrains ? "_constrained" : "") << hp_string << '_'
                << i << ".vtk";
 
       std::ofstream output(filename.str().c_str());
diff --git a/tests/hp/limit_p_level_difference_04.cc b/tests/hp/limit_p_level_difference_04.cc
index e240290671..6fe3c80b37 100644
--- a/tests/hp/limit_p_level_difference_04.cc
+++ b/tests/hp/limit_p_level_difference_04.cc
@@ -91,14 +91,14 @@ test(const unsigned int max_difference)
 
   deallog << "future FE indices before adaptation:" << std::endl;
   for (const auto &cell : dofh.active_cell_iterators())
-    deallog << " " << cell->id().to_string() << " " << cell->future_fe_index()
+    deallog << ' ' << cell->id().to_string() << ' ' << cell->future_fe_index()
             << std::endl;
 
   tria.execute_coarsening_and_refinement();
 
   deallog << "active FE indices after adaptation:" << std::endl;
   for (const auto &cell : dofh.active_cell_iterators())
-    deallog << " " << cell->id().to_string() << " " << cell->active_fe_index()
+    deallog << ' ' << cell->id().to_string() << ' ' << cell->active_fe_index()
             << std::endl;
 
   deallog << "OK" << std::endl;
diff --git a/tests/hp/p_adaptivity_absolute_threshold.cc b/tests/hp/p_adaptivity_absolute_threshold.cc
index 891621068c..6b4d494d53 100644
--- a/tests/hp/p_adaptivity_absolute_threshold.cc
+++ b/tests/hp/p_adaptivity_absolute_threshold.cc
@@ -43,7 +43,7 @@ validate(const DoFHandler<dim> &dh)
 {
   deallog << " fe_indices:";
   for (const auto &cell : dh.active_cell_iterators())
-    deallog << " " << cell->future_fe_index();
+    deallog << ' ' << cell->future_fe_index();
   deallog << std::endl;
 }
 
diff --git a/tests/hp/p_adaptivity_fixed_number.cc b/tests/hp/p_adaptivity_fixed_number.cc
index 6016701313..75a6fc3c29 100644
--- a/tests/hp/p_adaptivity_fixed_number.cc
+++ b/tests/hp/p_adaptivity_fixed_number.cc
@@ -43,7 +43,7 @@ validate(const DoFHandler<dim> &dh)
 {
   deallog << " fe_indices:";
   for (const auto &cell : dh.active_cell_iterators())
-    deallog << " " << cell->future_fe_index();
+    deallog << ' ' << cell->future_fe_index();
   deallog << std::endl;
 }
 
diff --git a/tests/hp/p_adaptivity_flags.cc b/tests/hp/p_adaptivity_flags.cc
index 1bdd24940a..dcea6bf57d 100644
--- a/tests/hp/p_adaptivity_flags.cc
+++ b/tests/hp/p_adaptivity_flags.cc
@@ -43,7 +43,7 @@ validate(const DoFHandler<dim> &dh)
 {
   deallog << " fe_indices:";
   for (const auto &cell : dh.active_cell_iterators())
-    deallog << " " << cell->future_fe_index();
+    deallog << ' ' << cell->future_fe_index();
   deallog << std::endl;
 }
 
diff --git a/tests/hp/p_adaptivity_full.cc b/tests/hp/p_adaptivity_full.cc
index 8948f2b277..c34c5241de 100644
--- a/tests/hp/p_adaptivity_full.cc
+++ b/tests/hp/p_adaptivity_full.cc
@@ -43,7 +43,7 @@ validate(const DoFHandler<dim> &dh)
 {
   deallog << " fe_indices:";
   for (const auto &cell : dh.active_cell_iterators())
-    deallog << " " << cell->future_fe_index();
+    deallog << ' ' << cell->future_fe_index();
   deallog << std::endl;
 }
 
diff --git a/tests/hp/p_adaptivity_reference.cc b/tests/hp/p_adaptivity_reference.cc
index d90956c457..823d7900f6 100644
--- a/tests/hp/p_adaptivity_reference.cc
+++ b/tests/hp/p_adaptivity_reference.cc
@@ -43,7 +43,7 @@ validate(const DoFHandler<dim> &dh)
 {
   deallog << " fe_indices:";
   for (const auto &cell : dh.active_cell_iterators())
-    deallog << " " << cell->future_fe_index();
+    deallog << ' ' << cell->future_fe_index();
   deallog << std::endl;
 }
 
diff --git a/tests/hp/p_adaptivity_regularity.cc b/tests/hp/p_adaptivity_regularity.cc
index 1587a86d4a..9ae39d62ad 100644
--- a/tests/hp/p_adaptivity_regularity.cc
+++ b/tests/hp/p_adaptivity_regularity.cc
@@ -43,7 +43,7 @@ validate(const DoFHandler<dim> &dh)
 {
   deallog << " fe_indices:";
   for (const auto &cell : dh.active_cell_iterators())
-    deallog << " " << cell->future_fe_index();
+    deallog << ' ' << cell->future_fe_index();
   deallog << std::endl;
 }
 
diff --git a/tests/hp/p_adaptivity_relative_threshold.cc b/tests/hp/p_adaptivity_relative_threshold.cc
index eb87fd9e7f..162fa11d0f 100644
--- a/tests/hp/p_adaptivity_relative_threshold.cc
+++ b/tests/hp/p_adaptivity_relative_threshold.cc
@@ -43,7 +43,7 @@ validate(const DoFHandler<dim> &dh)
 {
   deallog << " fe_indices:";
   for (const auto &cell : dh.active_cell_iterators())
-    deallog << " " << cell->future_fe_index();
+    deallog << ' ' << cell->future_fe_index();
   deallog << std::endl;
 }
 
diff --git a/tests/hp/set_dof_values_by_interpolation_03.cc b/tests/hp/set_dof_values_by_interpolation_03.cc
index 5516b9b802..2cbfc6d66d 100644
--- a/tests/hp/set_dof_values_by_interpolation_03.cc
+++ b/tests/hp/set_dof_values_by_interpolation_03.cc
@@ -46,7 +46,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   // create a hp::DoFHandler with different finite elements on the
   // cells. note that we skip setting active_fe_indices on inactive
diff --git a/tests/hp/step-11.cc b/tests/hp/step-11.cc
index 4e499c9f3e..06fc662e97 100644
--- a/tests/hp/step-11.cc
+++ b/tests/hp/step-11.cc
@@ -93,7 +93,7 @@ LaplaceProblem<dim>::LaplaceProblem(const unsigned int mapping_degree)
   , dof_handler(triangulation)
   , mapping(MappingQ<dim>(mapping_degree))
 {
-  deallog << "Using mapping with degree " << mapping_degree << ":" << std::endl
+  deallog << "Using mapping with degree " << mapping_degree << ':' << std::endl
           << "============================" << std::endl;
 }
 
diff --git a/tests/hp/step-13.cc b/tests/hp/step-13.cc
index de8d0338f5..d6092b6595 100644
--- a/tests/hp/step-13.cc
+++ b/tests/hp/step-13.cc
@@ -192,7 +192,7 @@ namespace Evaluation
     data_out.build_patches();
 
     std::ostringstream filename;
-    filename << output_name_base << "-" << this->refinement_cycle
+    filename << output_name_base << '-' << this->refinement_cycle
              << data_out.default_suffix(output_format) << std::ends;
 
     data_out.write(deallog.get_file_stream(), output_format);
@@ -728,7 +728,7 @@ run_simulation(
 
   for (unsigned int step = 0; true; ++step)
     {
-      deallog << step << " " << std::flush;
+      deallog << step << ' ' << std::flush;
 
       solver.solve_problem();
 
diff --git a/tests/lac/block_indices_02.cc b/tests/lac/block_indices_02.cc
index 0d2cc2c4bd..33a5c29b75 100644
--- a/tests/lac/block_indices_02.cc
+++ b/tests/lac/block_indices_02.cc
@@ -45,7 +45,7 @@ test()
       const auto p = idx.global_to_local(i);
       AssertDimension(p.first, i / block_size);
       AssertDimension(p.second, i % block_size);
-      deallog << i << " -> (" << p.first << "," << p.second << ")" << std::endl;
+      deallog << i << " -> (" << p.first << ',' << p.second << ')' << std::endl;
     }
 
   deallog << std::endl;
diff --git a/tests/lac/block_linear_operator_01.cc b/tests/lac/block_linear_operator_01.cc
index 7035e38f7b..526682ef6d 100644
--- a/tests/lac/block_linear_operator_01.cc
+++ b/tests/lac/block_linear_operator_01.cc
@@ -33,7 +33,7 @@
 #include "../tests.h"
 
 #define PRINTME(name, var)                               \
-  deallog << "Block vector: " name << ":" << std::endl;  \
+  deallog << "Block vector: " name << ':' << std::endl;  \
   for (unsigned int i = 0; i < var.n_blocks(); ++i)      \
     {                                                    \
       deallog << "[block " << i << " ]  " << std::flush; \
diff --git a/tests/lac/block_linear_operator_02.cc b/tests/lac/block_linear_operator_02.cc
index f2f6daea28..81d790844c 100644
--- a/tests/lac/block_linear_operator_02.cc
+++ b/tests/lac/block_linear_operator_02.cc
@@ -33,7 +33,7 @@
 #include "../tests.h"
 
 #define PRINTME(name, var)                               \
-  deallog << "Block vector: " name << ":" << std::endl;  \
+  deallog << "Block vector: " name << ':' << std::endl;  \
   for (unsigned int i = 0; i < var.n_blocks(); ++i)      \
     {                                                    \
       deallog << "[block " << i << " ]  " << std::flush; \
diff --git a/tests/lac/block_linear_operator_04.cc b/tests/lac/block_linear_operator_04.cc
index abf59443bb..06f8a409b2 100644
--- a/tests/lac/block_linear_operator_04.cc
+++ b/tests/lac/block_linear_operator_04.cc
@@ -25,7 +25,7 @@
 #include "../tests.h"
 
 #define PRINTME(name, var)                                            \
-  deallog << "Block vector: " name << ":" << std::endl;               \
+  deallog << "Block vector: " name << ':' << std::endl;               \
   for (unsigned int i = 0; i < var.n_blocks(); ++i)                   \
     deallog << "[block " << i << " ]  " << var.block(i) << std::endl; \
   deallog << std::endl;
diff --git a/tests/lac/block_linear_operator_06.cc b/tests/lac/block_linear_operator_06.cc
index 789e2c8974..fb55ae65d5 100644
--- a/tests/lac/block_linear_operator_06.cc
+++ b/tests/lac/block_linear_operator_06.cc
@@ -33,7 +33,7 @@
 #include "../tests.h"
 
 #define PRINTME(name, var)                                            \
-  deallog << "Block vector: " name << ":" << std::endl;               \
+  deallog << "Block vector: " name << ':' << std::endl;               \
   for (unsigned int i = 0; i < var.n_blocks(); ++i)                   \
     deallog << "[block " << i << " ]  " << var.block(i) << std::endl; \
   deallog << std::endl;
diff --git a/tests/lac/block_vector_move_operations.cc b/tests/lac/block_vector_move_operations.cc
index 80f6d1059a..6afd9f7c60 100644
--- a/tests/lac/block_vector_move_operations.cc
+++ b/tests/lac/block_vector_move_operations.cc
@@ -19,7 +19,7 @@
 #include "../tests.h"
 
 #define PRINTME(name, var)                              \
-  deallog << "Block vector: " name << ":" << std::endl; \
+  deallog << "Block vector: " name << ':' << std::endl; \
   for (unsigned int i = 0; i < var.n_blocks(); ++i)     \
     deallog << "[block " << i << " ]  " << var.block(i) << std::endl;
 
diff --git a/tests/lac/constraint_matrix_distribute_local_global.cc b/tests/lac/constraint_matrix_distribute_local_global.cc
index 9e5b669057..b213c9998d 100644
--- a/tests/lac/constraint_matrix_distribute_local_global.cc
+++ b/tests/lac/constraint_matrix_distribute_local_global.cc
@@ -56,7 +56,7 @@ main()
   for (unsigned int m = 0; m < global_matrix.m(); ++m)
     {
       for (unsigned int n = 0; n < global_matrix.n(); ++n)
-        deallog << global_matrix(m, n) << " ";
+        deallog << global_matrix(m, n) << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
@@ -70,7 +70,7 @@ main()
   for (unsigned int m = 0; m < global_matrix.m(); ++m)
     {
       for (unsigned int n = 0; n < global_matrix.n(); ++n)
-        deallog << global_matrix(m, n) << " ";
+        deallog << global_matrix(m, n) << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/lac/constraints_get_lines.cc b/tests/lac/constraints_get_lines.cc
index fbc8cbc59d..ca82efb3ea 100644
--- a/tests/lac/constraints_get_lines.cc
+++ b/tests/lac/constraints_get_lines.cc
@@ -54,7 +54,7 @@ test()
       deallog << line.index;
       for (auto entry : line.entries)
         {
-          deallog << " (" << entry.first << "," << entry.second << ")";
+          deallog << " (" << entry.first << ',' << entry.second << ')';
         }
       deallog << " - " << line.inhomogeneity << std::endl;
     }
diff --git a/tests/lac/diagonal_matrix_02.cc b/tests/lac/diagonal_matrix_02.cc
index bdbd143ef4..61a2b1e048 100644
--- a/tests/lac/diagonal_matrix_02.cc
+++ b/tests/lac/diagonal_matrix_02.cc
@@ -158,7 +158,7 @@ test(const bool hanging_nodes = true)
       const double t = sparse_matrix.diag_element(glob_index);
       if (std::abs(d - t) / t > 1e-10)
         {
-          deallog << glob_index << " " << d << " != " << t << std::endl;
+          deallog << glob_index << ' ' << d << " != " << t << std::endl;
         }
     }
 
diff --git a/tests/lac/la_vector_add_and_dot.cc b/tests/lac/la_vector_add_and_dot.cc
index b6db93566a..6ef89ed019 100644
--- a/tests/lac/la_vector_add_and_dot.cc
+++ b/tests/lac/la_vector_add_and_dot.cc
@@ -50,18 +50,18 @@ check()
         {
           deallog << "Vector add reference:   ";
           for (unsigned int i = 0; i < size; ++i)
-            deallog << v1[i] << " ";
+            deallog << v1[i] << ' ';
           deallog << std::endl;
           deallog << "Vector check reference: ";
           for (unsigned int i = 0; i < size; ++i)
-            deallog << check[i] << " ";
+            deallog << check[i] << ' ';
           deallog << std::endl;
 
           const number constant = 1.;
           v1.add(constant);
           deallog << "Vector add constant:    ";
           for (unsigned int i = 0; i < size; ++i)
-            deallog << v1[i] << " ";
+            deallog << v1[i] << ' ';
           deallog << std::endl;
         }
 
diff --git a/tests/lac/linear_operator_06.cc b/tests/lac/linear_operator_06.cc
index 2a70f3c605..ddbcae54a5 100644
--- a/tests/lac/linear_operator_06.cc
+++ b/tests/lac/linear_operator_06.cc
@@ -25,7 +25,7 @@
 #include "../tests.h"
 
 #define PRINTME(name, var)                              \
-  deallog << "Block vector: " name << ":" << std::endl; \
+  deallog << "Block vector: " name << ':' << std::endl; \
   for (unsigned int i = 0; i < var.n_blocks(); ++i)     \
     deallog << "[block " << i << " ]  " << var.block(i);
 
diff --git a/tests/lac/linear_operator_07.cc b/tests/lac/linear_operator_07.cc
index 511cdcfef5..d56dd3706f 100644
--- a/tests/lac/linear_operator_07.cc
+++ b/tests/lac/linear_operator_07.cc
@@ -25,7 +25,7 @@
 #include "../tests.h"
 
 #define PRINTME(name, var)                              \
-  deallog << "Block vector: " name << ":" << std::endl; \
+  deallog << "Block vector: " name << ':' << std::endl; \
   for (unsigned int i = 0; i < var.n_blocks(); ++i)     \
     deallog << "[block " << i << " ]  " << var.block(i);
 
diff --git a/tests/lac/linear_operator_10.cc b/tests/lac/linear_operator_10.cc
index dd8f8d688c..367e21001b 100644
--- a/tests/lac/linear_operator_10.cc
+++ b/tests/lac/linear_operator_10.cc
@@ -35,7 +35,7 @@ print(const VECTOR &vec)
 {
   for (types::global_dof_index i = 0; i < vec.size(); ++i)
     {
-      deallog << vec(i) << " ";
+      deallog << vec(i) << ' ';
     }
   deallog << std::endl;
 }
diff --git a/tests/lac/linear_operator_10a.cc b/tests/lac/linear_operator_10a.cc
index 62ba3a69cd..8e983f1922 100644
--- a/tests/lac/linear_operator_10a.cc
+++ b/tests/lac/linear_operator_10a.cc
@@ -40,7 +40,7 @@ print(const VECTOR &vec)
 {
   for (types::global_dof_index i = 0; i < vec.size(); ++i)
     {
-      deallog << vec(i) << " ";
+      deallog << vec(i) << ' ';
     }
   deallog << std::endl;
 }
diff --git a/tests/lac/precondition_chebyshev_01.cc b/tests/lac/precondition_chebyshev_01.cc
index 7af71d4388..34154a7267 100644
--- a/tests/lac/precondition_chebyshev_01.cc
+++ b/tests/lac/precondition_chebyshev_01.cc
@@ -61,19 +61,19 @@ check()
 
   deallog << "Exact inverse:     ";
   for (unsigned int i = 0; i < size; ++i)
-    deallog << in(i) / m(i, i) << " ";
+    deallog << in(i) / m(i, i) << ' ';
   deallog << std::endl;
 
   deallog << "Check  vmult orig: ";
   prec.vmult(out, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   deallog << std::endl;
 
   deallog << "Check Tvmult orig: ";
   prec.Tvmult(out, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   deallog << std::endl;
 
   Vector<double> matrix_diagonal(size);
@@ -86,13 +86,13 @@ check()
   deallog << "Check  vmult diag: ";
   prec.vmult(out, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   deallog << std::endl;
 
   deallog << "Check Tvmult diag: ";
   prec.Tvmult(out, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/lac/precondition_chebyshev_02.cc b/tests/lac/precondition_chebyshev_02.cc
index ba3123e94b..58b0580062 100644
--- a/tests/lac/precondition_chebyshev_02.cc
+++ b/tests/lac/precondition_chebyshev_02.cc
@@ -95,19 +95,19 @@ check()
 
   deallog << "Exact inverse:     ";
   for (unsigned int i = 0; i < size; ++i)
-    deallog << in(i) / m(i, i) << " ";
+    deallog << in(i) / m(i, i) << ' ';
   deallog << std::endl;
 
   deallog << "Check  vmult ones: ";
   prec.vmult(out, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   deallog << std::endl;
 
   deallog << "Check Tvmult ones: ";
   prec.Tvmult(out, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   deallog << std::endl;
 
   data.preconditioner->reinit(m);
@@ -118,13 +118,13 @@ check()
   deallog << "Check  vmult diag: ";
   prec.vmult(out, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   deallog << std::endl;
 
   deallog << "Check Tvmult diag: ";
   prec.Tvmult(out, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/lac/precondition_chebyshev_04.cc b/tests/lac/precondition_chebyshev_04.cc
index c77abfdb60..d70c76c219 100644
--- a/tests/lac/precondition_chebyshev_04.cc
+++ b/tests/lac/precondition_chebyshev_04.cc
@@ -94,13 +94,13 @@ check()
 
   deallog << "Exact inverse:     ";
   for (unsigned int i = 0; i < size; ++i)
-    deallog << in(i) / m(i, i) << " ";
+    deallog << in(i) / m(i, i) << ' ';
   deallog << std::endl;
 
   deallog << "Check  vmult usual init: ";
   prec.vmult(ref, in);
   for (unsigned int i = 0; i < size; ++i)
-    deallog << ref(i) << " ";
+    deallog << ref(i) << ' ';
   deallog << std::endl;
 
   prec.initialize(m, data);
@@ -109,7 +109,7 @@ check()
   prec.vmult(out, in);
   deallog << "Check  vmult zero init:  ";
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   out -= ref;
   deallog << " difference norm = " << out.linfty_norm() << std::endl;
 
@@ -122,7 +122,7 @@ check()
   prec2.vmult(out, in);
   deallog << "Check  vmult zero init:  ";
   for (unsigned int i = 0; i < size; ++i)
-    deallog << out(i) << " ";
+    deallog << out(i) << ' ';
   out -= ref;
   deallog << " difference norm = " << out.linfty_norm() << std::endl;
 }
diff --git a/tests/lac/qr.cc b/tests/lac/qr.cc
index ac74929881..c9f182af1c 100644
--- a/tests/lac/qr.cc
+++ b/tests/lac/qr.cc
@@ -114,7 +114,7 @@ test()
       {
         deallog.get_file_stream() << std::setw(9) << Q[j](i);
         if (j < size - 1)
-          deallog.get_file_stream() << " ";
+          deallog.get_file_stream() << ' ';
         else
           deallog.get_file_stream() << std::endl;
       }
diff --git a/tests/lac/qr_02.cc b/tests/lac/qr_02.cc
index 7ce978b76a..b83d652f85 100644
--- a/tests/lac/qr_02.cc
+++ b/tests/lac/qr_02.cc
@@ -91,7 +91,7 @@ print(const QR<VectorType> &qr, const unsigned int v_size)
       {
         deallog.get_file_stream() << std::setw(9) << Q[j](i);
         if (j < size - 1)
-          deallog.get_file_stream() << " ";
+          deallog.get_file_stream() << ' ';
         else
           deallog.get_file_stream() << std::endl;
       }
@@ -107,8 +107,8 @@ test()
   auto print_givens = [](const unsigned int           i,
                          const unsigned int           j,
                          const std::array<number, 3> &csr) {
-    deallog.get_file_stream() << "Givens " << i << " " << j << ": " << csr[0]
-                              << " " << csr[1] << " " << csr[2] << std::endl;
+    deallog.get_file_stream() << "Givens " << i << ' ' << j << ": " << csr[0]
+                              << ' ' << csr[1] << ' ' << csr[2] << std::endl;
   };
   qr.connect_givens_slot(print_givens);
 
diff --git a/tests/lac/qr_03.cc b/tests/lac/qr_03.cc
index 57a20e5896..3760c60679 100644
--- a/tests/lac/qr_03.cc
+++ b/tests/lac/qr_03.cc
@@ -116,7 +116,7 @@ test()
       {
         deallog.get_file_stream() << std::setw(9) << Q[j](i);
         if (j < size - 1)
-          deallog.get_file_stream() << " ";
+          deallog.get_file_stream() << ' ';
         else
           deallog.get_file_stream() << std::endl;
       }
diff --git a/tests/lac/qr_04.cc b/tests/lac/qr_04.cc
index bcc6431b5a..c061cf8561 100644
--- a/tests/lac/qr_04.cc
+++ b/tests/lac/qr_04.cc
@@ -91,7 +91,7 @@ print(const ImplicitQR<VectorType> &qr, const unsigned int col_size)
       {
         deallog.get_file_stream() << std::setw(9) << A[j](i);
         if (j < size - 1)
-          deallog.get_file_stream() << " ";
+          deallog.get_file_stream() << ' ';
         else
           deallog.get_file_stream() << std::endl;
       }
@@ -107,8 +107,8 @@ test()
   auto print_givens = [](const unsigned int           i,
                          const unsigned int           j,
                          const std::array<number, 3> &csr) {
-    deallog.get_file_stream() << "Givens " << i << " " << j << ": " << csr[0]
-                              << " " << csr[1] << " " << csr[2] << std::endl;
+    deallog.get_file_stream() << "Givens " << i << ' ' << j << ": " << csr[0]
+                              << ' ' << csr[1] << ' ' << csr[2] << std::endl;
   };
   qr.connect_givens_slot(print_givens);
 
diff --git a/tests/lac/qr_08.cc b/tests/lac/qr_08.cc
index 2f92867c7e..0eef4b4832 100644
--- a/tests/lac/qr_08.cc
+++ b/tests/lac/qr_08.cc
@@ -129,7 +129,7 @@ print(const QR<VectorType> &qr, const unsigned int col_size)
       {
         deallog.get_file_stream() << std::setw(9) << Q[j](i);
         if (j < size - 1)
-          deallog.get_file_stream() << " ";
+          deallog.get_file_stream() << ' ';
         else
           deallog.get_file_stream() << std::endl;
       }
diff --git a/tests/lac/qr_10.cc b/tests/lac/qr_10.cc
index 43c17ae626..27394722b9 100644
--- a/tests/lac/qr_10.cc
+++ b/tests/lac/qr_10.cc
@@ -145,7 +145,7 @@ test()
       {
         deallog.get_file_stream() << std::setw(9) << A[j](i);
         if (j < size - 1)
-          deallog.get_file_stream() << " ";
+          deallog.get_file_stream() << ' ';
         else
           deallog.get_file_stream() << std::endl;
       }
diff --git a/tests/lac/solver_signals.cc b/tests/lac/solver_signals.cc
index aa9f25cf8b..91d48588da 100644
--- a/tests/lac/solver_signals.cc
+++ b/tests/lac/solver_signals.cc
@@ -67,7 +67,7 @@ output_hessenberg_matrix(const FullMatrix<NUMBER> &H, const std::string &text)
   for (unsigned int i = 0; i < H.m(); ++i)
     {
       for (unsigned int j = 0; j < H.n(); ++j)
-        deallog << H(i, j) << " ";
+        deallog << H(i, j) << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/lac/tridiagonal_matrix.cc b/tests/lac/tridiagonal_matrix.cc
index 8ffa83c140..e0e3d33fe4 100644
--- a/tests/lac/tridiagonal_matrix.cc
+++ b/tests/lac/tridiagonal_matrix.cc
@@ -177,7 +177,7 @@ check(unsigned int size)
   TridiagonalMatrix<number> M(size);
   deallog << "all_zero " << M.all_zero();
   matrix1(M);
-  deallog << " " << M.all_zero() << std::endl;
+  deallog << ' ' << M.all_zero() << std::endl;
   deallog << "Matrix [-1,2,-1]" << std::endl;
   M.print(deallog, 7, 0);
   check_vmult(M);
diff --git a/tests/lac/tridiagonal_matrix_sym.cc b/tests/lac/tridiagonal_matrix_sym.cc
index 586f0b317d..53878b7582 100644
--- a/tests/lac/tridiagonal_matrix_sym.cc
+++ b/tests/lac/tridiagonal_matrix_sym.cc
@@ -131,7 +131,7 @@ check(unsigned int size)
   TridiagonalMatrix<number> M(size, true);
   deallog << "all_zero " << M.all_zero();
   matrix1(M);
-  deallog << " " << M.all_zero() << std::endl;
+  deallog << ' ' << M.all_zero() << std::endl;
   deallog << "Matrix [-1,2,-1]" << std::endl;
   M.print(deallog, 7, 0);
   check_vmult(M);
diff --git a/tests/lac/utilities_02.cc b/tests/lac/utilities_02.cc
index 1c2f138aaa..027dbc7de9 100644
--- a/tests/lac/utilities_02.cc
+++ b/tests/lac/utilities_02.cc
@@ -181,7 +181,7 @@ test()
     {
       const double est = Utilities::LinearAlgebra::lanczos_largest_eigenvalue(
         OP, init_vector, k, vector_memory);
-      deallog << k << " " << est << std::endl;
+      deallog << k << ' ' << est << std::endl;
     }
 
     // exact eigenvectors via PArpack
diff --git a/tests/lac/utilities_03.cc b/tests/lac/utilities_03.cc
index 453f43a5a1..58eec470cf 100644
--- a/tests/lac/utilities_03.cc
+++ b/tests/lac/utilities_03.cc
@@ -119,7 +119,7 @@ check(const int          degree,
         x(i) = random_value<double>();
       }
 
-  deallog << " Modes inside/outside: " << n_in << " " << n_out << std::endl;
+  deallog << " Modes inside/outside: " << n_in << ' ' << n_out << std::endl;
 
   // for x = x_i v_i , where v_i are eigenvectors
   // p[H]x = \sum_i x_i p(\lambda_i) v_i
@@ -142,7 +142,7 @@ check(const int          degree,
   diff = y;
   diff -= exact;
 
-  deallog << " Filter [" << a << "," << b << "]" << std::endl;
+  deallog << " Filter [" << a << ',' << b << ']' << std::endl;
   deallog << " Error: " << diff.linfty_norm() / exact.linfty_norm()
           << std::endl;
 
diff --git a/tests/lac/vector_accumulation_02.cc b/tests/lac/vector_accumulation_02.cc
index 165513b4a3..8f50a869f8 100644
--- a/tests/lac/vector_accumulation_02.cc
+++ b/tests/lac/vector_accumulation_02.cc
@@ -60,7 +60,7 @@ check_norms()
 
             const number result = v1 * v2;
             deallog << static_cast<double>(std::abs(result - inner_product))
-                    << " ";
+                    << ' ';
           }
       deallog << std::endl;
     }
diff --git a/tests/lac/vector_reinit_01.cc b/tests/lac/vector_reinit_01.cc
index fefb671ddc..50fdfccb73 100644
--- a/tests/lac/vector_reinit_01.cc
+++ b/tests/lac/vector_reinit_01.cc
@@ -39,7 +39,7 @@ do_test()
     MPI_Comm communicator =
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v1.reinit(set, communicator);
-    deallog << "reinit: " << v1.size() << " ";
+    deallog << "reinit: " << v1.size() << ' ';
 
 #ifdef DEAL_II_WITH_MPI
     MPI_Comm_free(&communicator);
@@ -51,7 +51,7 @@ do_test()
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v2.reinit(set, communicator);
     v1.reinit(v2);
-    deallog << v1.size() << " ";
+    deallog << v1.size() << ' ';
     v1.reinit(v2);
     deallog << v1.size() << std::endl;
 
@@ -65,7 +65,7 @@ do_test()
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v2.reinit(set, communicator);
     v1 = v2;
-    deallog << "assign " << v1.size() << " ";
+    deallog << "assign " << v1.size() << ' ';
     v1 = v2;
     deallog << v1.size() << std::endl;
 
@@ -81,7 +81,7 @@ do_test()
     typename VectorMemory<VectorType>::Pointer v3(memory);
     v1.reinit(set, communicator);
     v3->reinit(v1);
-    deallog << "reinit pool " << v1.size() << " " << v3->size() << " ";
+    deallog << "reinit pool " << v1.size() << ' ' << v3->size() << ' ';
 
 #ifdef DEAL_II_WITH_MPI
     MPI_Comm_free(&communicator);
diff --git a/tests/lac/vector_reinit_02.cc b/tests/lac/vector_reinit_02.cc
index 6efc6526f9..d299e51bb0 100644
--- a/tests/lac/vector_reinit_02.cc
+++ b/tests/lac/vector_reinit_02.cc
@@ -39,7 +39,7 @@ do_test()
     MPI_Comm communicator =
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v1.reinit(set, communicator);
-    deallog << "reinit: " << v1.size() << " ";
+    deallog << "reinit: " << v1.size() << ' ';
 
 #ifdef DEAL_II_WITH_MPI
     MPI_Comm_free(&communicator);
@@ -51,7 +51,7 @@ do_test()
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v2.reinit(set, communicator);
     v1.reinit(v2);
-    deallog << v1.size() << " ";
+    deallog << v1.size() << ' ';
     v1.reinit(v2);
     deallog << v1.size() << std::endl;
 
@@ -65,7 +65,7 @@ do_test()
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v2.reinit(set, communicator);
     v1 = v2;
-    deallog << "assign " << v1.size() << " ";
+    deallog << "assign " << v1.size() << ' ';
     v1 = v2;
     deallog << v1.size() << std::endl;
 
@@ -81,7 +81,7 @@ do_test()
     typename VectorMemory<VectorType>::Pointer v3(memory);
     v1.reinit(set, communicator);
     v3->reinit(v1);
-    deallog << "reinit pool " << v1.size() << " " << v3->size() << " ";
+    deallog << "reinit pool " << v1.size() << ' ' << v3->size() << ' ';
 
 #ifdef DEAL_II_WITH_MPI
     MPI_Comm_free(&communicator);
diff --git a/tests/lac/vector_reinit_03.cc b/tests/lac/vector_reinit_03.cc
index 89fce96cfe..5593cc0669 100644
--- a/tests/lac/vector_reinit_03.cc
+++ b/tests/lac/vector_reinit_03.cc
@@ -39,7 +39,7 @@ do_test()
     MPI_Comm communicator =
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v1.reinit(set, communicator);
-    deallog << "reinit: " << v1.size() << " ";
+    deallog << "reinit: " << v1.size() << ' ';
 
 #ifdef DEAL_II_WITH_MPI
     MPI_Comm_free(&communicator);
@@ -51,7 +51,7 @@ do_test()
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v2.reinit(set, communicator);
     v1.reinit(v2);
-    deallog << v1.size() << " ";
+    deallog << v1.size() << ' ';
     v1.reinit(v2);
     deallog << v1.size() << std::endl;
 
@@ -65,7 +65,7 @@ do_test()
       Utilities::MPI::duplicate_communicator(MPI_COMM_WORLD);
     v2.reinit(set, communicator);
     v1 = v2;
-    deallog << "assign " << v1.size() << " ";
+    deallog << "assign " << v1.size() << ' ';
     v1 = v2;
     deallog << v1.size() << std::endl;
 
@@ -81,7 +81,7 @@ do_test()
     typename VectorMemory<VectorType>::Pointer v3(memory);
     v1.reinit(set, communicator);
     v3->reinit(v1);
-    deallog << "reinit pool " << v1.size() << " " << v3->size() << " ";
+    deallog << "reinit pool " << v1.size() << ' ' << v3->size() << ' ';
 
 #ifdef DEAL_II_WITH_MPI
     MPI_Comm_free(&communicator);
diff --git a/tests/lapack/full_matrix_17.cc b/tests/lapack/full_matrix_17.cc
index 218fa3d50d..a25050c2ec 100644
--- a/tests/lapack/full_matrix_17.cc
+++ b/tests/lapack/full_matrix_17.cc
@@ -47,7 +47,7 @@ test(const unsigned int size)
   M.compute_cholesky_factorization();
   const double rcond = M.reciprocal_condition_number(la_l1);
 
-  deallog << 1. / (l1 * inv_l1) << " " << rcond << std::endl;
+  deallog << 1. / (l1 * inv_l1) << ' ' << rcond << std::endl;
 }
 
 
diff --git a/tests/lapack/full_matrix_31.cc b/tests/lapack/full_matrix_31.cc
index 6043e12382..d1ac144468 100644
--- a/tests/lapack/full_matrix_31.cc
+++ b/tests/lapack/full_matrix_31.cc
@@ -34,7 +34,7 @@ DeclException5(ExcEl,
                double,
                double,
                double,
-               << "Error in element (" << arg1 << "," << arg2 << "): " << arg3
+               << "Error in element (" << arg1 << ',' << arg2 << "): " << arg3
                << " != " << arg4 << " delta=" << arg5);
 
 template <typename NumberType>
@@ -44,7 +44,7 @@ test(const unsigned int m,
      const unsigned int k,
      const NumberType   eps)
 {
-  deallog << m << " " << n << " " << k << " " << std::endl;
+  deallog << m << ' ' << n << ' ' << k << ' ' << std::endl;
   FullMatrix<NumberType>       A(k, m), B(k, n), C(m, n), D(k, k);
   LAPACKFullMatrix<NumberType> AL(k, m), BL(k, n), CL(m, n);
   Vector<NumberType>           DL(k);
diff --git a/tests/lapack/full_matrix_32.cc b/tests/lapack/full_matrix_32.cc
index 179e5b2674..734465589f 100644
--- a/tests/lapack/full_matrix_32.cc
+++ b/tests/lapack/full_matrix_32.cc
@@ -33,14 +33,14 @@ DeclException5(ExcEl,
                double,
                double,
                double,
-               << "Error in element (" << arg1 << "," << arg2 << "): " << arg3
+               << "Error in element (" << arg1 << ',' << arg2 << "): " << arg3
                << " != " << arg4 << " delta=" << arg5);
 
 template <typename NumberType>
 void
 test(const unsigned int n, const unsigned int k, const NumberType eps)
 {
-  deallog << n << " " << k << " " << std::endl;
+  deallog << n << ' ' << k << ' ' << std::endl;
   FullMatrix<NumberType>       A(k, n), C(k, n), D(k, k);
   LAPACKFullMatrix<NumberType> AL(k, n);
   Vector<NumberType>           DL(k);
diff --git a/tests/lapack/full_matrix_33.cc b/tests/lapack/full_matrix_33.cc
index 4ceee59c65..1d7babd763 100644
--- a/tests/lapack/full_matrix_33.cc
+++ b/tests/lapack/full_matrix_33.cc
@@ -33,14 +33,14 @@ DeclException5(ExcEl,
                double,
                double,
                double,
-               << "Error in element (" << arg1 << "," << arg2 << "): " << arg3
+               << "Error in element (" << arg1 << ',' << arg2 << "): " << arg3
                << " != " << arg4 << " delta=" << arg5);
 
 template <typename NumberType>
 void
 test(const unsigned int n, const unsigned int k, const NumberType eps)
 {
-  deallog << n << " " << k << " " << std::endl;
+  deallog << n << ' ' << k << ' ' << std::endl;
   FullMatrix<NumberType>       A(k, n), C(n, n);
   LAPACKFullMatrix<NumberType> AL(k, n), CL(n, n);
 
diff --git a/tests/lapack/full_matrix_34.cc b/tests/lapack/full_matrix_34.cc
index 76df275224..7dc87ef2bb 100644
--- a/tests/lapack/full_matrix_34.cc
+++ b/tests/lapack/full_matrix_34.cc
@@ -33,14 +33,14 @@ DeclException5(ExcEl,
                double,
                double,
                double,
-               << "Error in element (" << arg1 << "," << arg2 << "): " << arg3
+               << "Error in element (" << arg1 << ',' << arg2 << "): " << arg3
                << " != " << arg4 << " delta=" << arg5);
 
 template <typename NumberType>
 void
 test(const unsigned int n, const unsigned int k, const NumberType eps)
 {
-  deallog << n << " " << k << " " << std::endl;
+  deallog << n << ' ' << k << ' ' << std::endl;
   FullMatrix<NumberType>       A(n, k), C(n, n);
   LAPACKFullMatrix<NumberType> AL(n, k), CL(n, n);
 
diff --git a/tests/manifold/chart_manifold_04.cc b/tests/manifold/chart_manifold_04.cc
index 77b7a0b6a5..a74a74a892 100644
--- a/tests/manifold/chart_manifold_04.cc
+++ b/tests/manifold/chart_manifold_04.cc
@@ -111,8 +111,8 @@ test(unsigned int ref, const MappingQ<dim> &mapping)
           deallog << "  p(" << q << "): " << fe_values.quadrature_point(q)
                   << std::endl;
           for (unsigned int i = 0; i < fe_values.dofs_per_cell; ++i)
-            deallog << "  shape " << i << "," << q << ": "
-                    << fe_values.shape_value(i, q) << " "
+            deallog << "  shape " << i << ',' << q << ": "
+                    << fe_values.shape_value(i, q) << ' '
                     << fe_values.shape_grad(i, q) << std::endl;
         }
 
diff --git a/tests/manifold/chart_manifold_04_embedded.cc b/tests/manifold/chart_manifold_04_embedded.cc
index 060b3d00ae..3e60d6c366 100644
--- a/tests/manifold/chart_manifold_04_embedded.cc
+++ b/tests/manifold/chart_manifold_04_embedded.cc
@@ -120,8 +120,8 @@ test(unsigned int ref, const MappingQ<dim> &mapping)
           deallog << "  p(" << q << "): " << fe_values.quadrature_point(q)
                   << std::endl;
           for (unsigned int i = 0; i < fe_values.dofs_per_cell; ++i)
-            deallog << "  shape " << i << "," << q << ": "
-                    << fe_values.shape_value(i, q) << " "
+            deallog << "  shape " << i << ',' << q << ": "
+                    << fe_values.shape_value(i, q) << ' '
                     << fe_values.shape_grad(i, q) << std::endl;
         }
 
diff --git a/tests/manifold/composition_manifold_02.cc b/tests/manifold/composition_manifold_02.cc
index 6095ecfeef..73943c4477 100644
--- a/tests/manifold/composition_manifold_02.cc
+++ b/tests/manifold/composition_manifold_02.cc
@@ -64,8 +64,8 @@ main()
 
   Point<2> center(0.0, 1.0);
 
-  out << center << " " << sp[0] << std::endl
-      << center << " " << sp[1] << std::endl;
+  out << center << ' ' << sp[0] << std::endl
+      << center << ' ' << sp[1] << std::endl;
 
   for (unsigned int i = 0; i < n_intermediates + 1; ++i)
     {
@@ -77,10 +77,10 @@ main()
       Tensor<1, spacedim> t1 = manifold.get_tangent_vector(ip, sp[0]);
       Tensor<1, spacedim> t2 = manifold.get_tangent_vector(ip, sp[1]);
 
-      out << ip << " " << t2 << std::endl;
+      out << ip << ' ' << t2 << std::endl;
     }
 
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 
   return 0;
 }
diff --git a/tests/manifold/composition_manifold_03.cc b/tests/manifold/composition_manifold_03.cc
index fe756ac8e1..43442d2871 100644
--- a/tests/manifold/composition_manifold_03.cc
+++ b/tests/manifold/composition_manifold_03.cc
@@ -69,8 +69,8 @@ main()
 
   Point<2> center;
 
-  out << center << " " << sp[0] << std::endl
-      << center << " " << sp[1] << std::endl;
+  out << center << ' ' << sp[0] << std::endl
+      << center << ' ' << sp[1] << std::endl;
 
   for (unsigned int i = 0; i < n_intermediates + 1; ++i)
     {
@@ -82,10 +82,10 @@ main()
       Tensor<1, spacedim> t1 = manifold.get_tangent_vector(ip, sp[0]);
       Tensor<1, spacedim> t2 = manifold.get_tangent_vector(ip, sp[1]);
 
-      out << ip << " " << t2 << std::endl;
+      out << ip << ' ' << t2 << std::endl;
     }
 
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 
   return 0;
 }
diff --git a/tests/manifold/composition_manifold_04.cc b/tests/manifold/composition_manifold_04.cc
index 727b68b1db..37a757ddcf 100644
--- a/tests/manifold/composition_manifold_04.cc
+++ b/tests/manifold/composition_manifold_04.cc
@@ -70,7 +70,7 @@ main()
       << "plot '-' with vectors " << std::endl;
 
   for (unsigned int v = 0; v < sp.size(); ++v)
-    out << center << " " << sp[v] << std::endl;
+    out << center << ' ' << sp[v] << std::endl;
 
 
   for (unsigned int i = 0; i < n_intermediates + 1; ++i)
@@ -83,10 +83,10 @@ main()
       Tensor<1, spacedim> t1 = manifold.get_tangent_vector(ip, sp[0]);
       Tensor<1, spacedim> t2 = manifold.get_tangent_vector(ip, sp[1]);
 
-      out << ip << " " << t2 << std::endl;
+      out << ip << ' ' << t2 << std::endl;
     }
 
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 
   out << "set terminal aqua " << 1 << std::endl
       << "set size ratio -1" << std::endl
@@ -104,7 +104,7 @@ main()
 
       out << ip << std::endl;
     }
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 
   return 0;
 }
diff --git a/tests/manifold/elliptical_manifold_03.cc b/tests/manifold/elliptical_manifold_03.cc
index ad72999421..a91c9ba804 100644
--- a/tests/manifold/elliptical_manifold_03.cc
+++ b/tests/manifold/elliptical_manifold_03.cc
@@ -67,7 +67,7 @@ main()
     ellipse.push_forward(chart_point_minusphi);
 
   deallog << "Gradient by finite differences: "
-          << (space_point_plusc - space_point_minusc) / (2.0 * h) << " "
+          << (space_point_plusc - space_point_minusc) / (2.0 * h) << ' '
           << (space_point_plusphi - space_point_minusphi) / (2.0 * h)
           << std::endl;
   deallog << "Analytic gradient:              "
diff --git a/tests/manifold/flat_manifold_04.cc b/tests/manifold/flat_manifold_04.cc
index bec8b6d114..1fdd353413 100644
--- a/tests/manifold/flat_manifold_04.cc
+++ b/tests/manifold/flat_manifold_04.cc
@@ -70,8 +70,8 @@ test(unsigned int ref, const MappingQ<dim> &mapping)
           deallog << "  p(" << q << "): " << fe_values.quadrature_point(q)
                   << std::endl;
           for (unsigned int i = 0; i < fe_values.dofs_per_cell; ++i)
-            deallog << "  shape " << i << "," << q << ": "
-                    << fe_values.shape_value(i, q) << " "
+            deallog << "  shape " << i << ',' << q << ": "
+                    << fe_values.shape_value(i, q) << ' '
                     << fe_values.shape_grad(i, q) << std::endl;
         }
 
diff --git a/tests/manifold/spherical_manifold_09.cc b/tests/manifold/spherical_manifold_09.cc
index 9591123b98..eb3761546a 100644
--- a/tests/manifold/spherical_manifold_09.cc
+++ b/tests/manifold/spherical_manifold_09.cc
@@ -53,7 +53,7 @@ main()
                 << (1.0 - cell->face(f)->vertex(1) *
                             spherical.normal_vector(cell->face(f),
                                                     cell->face(f)->vertex(1)))
-                << " "
+                << ' '
                 << (1.0 -
                     cell->face(f)->center(/*respect_manifold=*/true) *
                       spherical.normal_vector(cell->face(f),
@@ -70,7 +70,7 @@ main()
                 << (0.5 - cell->face(f)->vertex(1) *
                             spherical.normal_vector(cell->face(f),
                                                     cell->face(f)->vertex(1)))
-                << " "
+                << ' '
                 << (0.5 -
                     cell->face(f)->center(/*respect_manifold=*/true) *
                       spherical.normal_vector(cell->face(f),
diff --git a/tests/manifold/tensor_product_manifold_02.cc b/tests/manifold/tensor_product_manifold_02.cc
index dc04f99f0b..2b0000c0b4 100644
--- a/tests/manifold/tensor_product_manifold_02.cc
+++ b/tests/manifold/tensor_product_manifold_02.cc
@@ -52,7 +52,7 @@ test()
   out << "set view equal xyz" << std::endl
       << "splot '-' with lines, '-' with vectors " << std::endl;
   GridOut().write_gnuplot(tria, out);
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 
   Triangulation<2, 3>::active_cell_iterator it = tria.begin_active();
   for (; it != tria.end(); ++it)
@@ -62,9 +62,9 @@ test()
       Tensor<1, 3> t2 = manifold.get_tangent_vector(p, it->vertex(1));
       Tensor<1, 3> n  = cross_product_3d(t1, t2);
       n /= -n.norm();
-      out << it->center() << " " << n << std::endl;
+      out << it->center() << ' ' << n << std::endl;
     }
-  out << "e" << std::endl;
+  out << 'e' << std::endl;
 }
 
 
diff --git a/tests/mappings/fe_face_values_1d_mapping_cartesian.cc b/tests/mappings/fe_face_values_1d_mapping_cartesian.cc
index d04c57a647..3a25be5747 100644
--- a/tests/mappings/fe_face_values_1d_mapping_cartesian.cc
+++ b/tests/mappings/fe_face_values_1d_mapping_cartesian.cc
@@ -77,7 +77,7 @@ plot_faces(Mapping<dim> &                           mapping,
       // now print some data on the shape
       // functions
       for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-        deallog << "shape_function " << i << ":" << std::endl
+        deallog << "shape_function " << i << ':' << std::endl
                 << "  phi=" << fe_values.shape_value(i, 0) << std::endl
                 << "  grad phi=" << fe_values.shape_grad(i, 0) << std::endl
                 << "  grad^2 phi=" << fe_values.shape_hessian(i, 0)
@@ -123,7 +123,7 @@ plot_subfaces(Mapping<dim> &                           mapping,
         // now print some data on the shape
         // functions
         for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-          deallog << "shape_function " << i << ":" << std::endl
+          deallog << "shape_function " << i << ':' << std::endl
                   << "  phi=" << fe_values.shape_value(i, 0) << std::endl
                   << "  grad phi=" << fe_values.shape_grad(i, 0) << std::endl
                   << "  grad^2 phi=" << fe_values.shape_hessian(i, 0)
diff --git a/tests/mappings/fe_face_values_1d_mapping_q2.cc b/tests/mappings/fe_face_values_1d_mapping_q2.cc
index d251f9ef1d..2e7aabc1b0 100644
--- a/tests/mappings/fe_face_values_1d_mapping_q2.cc
+++ b/tests/mappings/fe_face_values_1d_mapping_q2.cc
@@ -77,7 +77,7 @@ plot_faces(Mapping<dim> &                           mapping,
       // now print some data on the shape
       // functions
       for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-        deallog << "shape_function " << i << ":" << std::endl
+        deallog << "shape_function " << i << ':' << std::endl
                 << "  phi=" << fe_values.shape_value(i, 0) << std::endl
                 << "  grad phi=" << fe_values.shape_grad(i, 0) << std::endl
                 << "  grad^2 phi=" << fe_values.shape_hessian(i, 0)
@@ -123,7 +123,7 @@ plot_subfaces(Mapping<dim> &                           mapping,
         // now print some data on the shape
         // functions
         for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-          deallog << "shape_function " << i << ":" << std::endl
+          deallog << "shape_function " << i << ':' << std::endl
                   << "  phi=" << fe_values.shape_value(i, 0) << std::endl
                   << "  grad phi=" << fe_values.shape_grad(i, 0) << std::endl
                   << "  grad^2 phi=" << fe_values.shape_hessian(i, 0)
diff --git a/tests/mappings/mapping.cc b/tests/mappings/mapping.cc
index 4607f52426..58e538ed21 100644
--- a/tests/mappings/mapping.cc
+++ b/tests/mappings/mapping.cc
@@ -479,7 +479,7 @@ mapping_test()
       dof.distribute_dofs(fe_q4);
       typename DoFHandler<dim>::cell_iterator cell = dof.begin_active();
 
-      deallog << "Triangulation" << i << ":" << std::endl;
+      deallog << "Triangulation" << i << ':' << std::endl;
 
       deallog << "exact_area=" << exact_areas[i] << std::endl;
       for (unsigned int j = 0; j < mapping_size; ++j)
diff --git a/tests/mappings/mapping_get_bounding_box_01.cc b/tests/mappings/mapping_get_bounding_box_01.cc
index bb06a87a44..6739b0fc42 100644
--- a/tests/mappings/mapping_get_bounding_box_01.cc
+++ b/tests/mappings/mapping_get_bounding_box_01.cc
@@ -37,8 +37,8 @@ void
 test_bounding_boxes(const Mapping<dim, spacedim> &mapping,
                     const unsigned int            degree)
 {
-  deallog << "Testing " << boost::core::demangle(typeid(mapping).name()) << "("
-          << degree << ")" << std::endl;
+  deallog << "Testing " << boost::core::demangle(typeid(mapping).name()) << '('
+          << degree << ')' << std::endl;
 
   Triangulation<dim, spacedim> triangulation;
   GridGenerator::hyper_ball(triangulation);
diff --git a/tests/mappings/mapping_manifold_06.cc b/tests/mappings/mapping_manifold_06.cc
index e5b5e633aa..7f45a25b52 100644
--- a/tests/mappings/mapping_manifold_06.cc
+++ b/tests/mappings/mapping_manifold_06.cc
@@ -91,7 +91,7 @@ test()
           }
       }
 
-  out << "e" << std::endl
+  out << 'e' << std::endl
       << std::endl
       << std::endl
       << "set terminal aqua " << 2 * (dim + spacedim) + 1 << std::endl
@@ -116,7 +116,7 @@ test()
               fe_v.get_normal_vectors();
             for (unsigned int i = 0; i < qps.size(); ++i)
               {
-                out << qps[i] << " " << nps[i] << std::endl;
+                out << qps[i] << ' ' << nps[i] << std::endl;
                 if (std::abs((center + nps[i] - qps[i]).norm()) > 1e-10)
                   out << "# Error! The normal vector should be radial! "
                       << std::endl
@@ -126,7 +126,7 @@ test()
             out << std::endl;
           }
       }
-  out << "e" << std::endl << std::endl;
+  out << 'e' << std::endl << std::endl;
 }
 
 
diff --git a/tests/mappings/mapping_q1_cartesian_grid.cc b/tests/mappings/mapping_q1_cartesian_grid.cc
index a03f82dfac..be14f72481 100644
--- a/tests/mappings/mapping_q1_cartesian_grid.cc
+++ b/tests/mappings/mapping_q1_cartesian_grid.cc
@@ -149,14 +149,14 @@ private:
 
         if ((test - dp_real).norm() > tol)
           {
-            deallog << " " << std::endl;
+            deallog << ' ' << std::endl;
             deallog << "ERROR" << std::endl;
             deallog << "cell = " << index << std::endl;
             deallog << "cell vertex(0): " << cell->vertex(0) << std::endl;
             deallog << "cell vertex(1): " << cell->vertex(1) << std::endl;
             deallog << "cell vertex(2): " << cell->vertex(2) << std::endl;
             deallog << "cell vertex(3): " << cell->vertex(3) << std::endl;
-            deallog << " " << std::endl;
+            deallog << ' ' << std::endl;
             deallog << "test point =   " << test << "  mapped point =   " << dp
                     << "  back-mapping =   " << dp_real << std::endl;
             deallog << "test point (unit mid) =   " << test_unit_mid
diff --git a/tests/mappings/mapping_q_cache_01.cc b/tests/mappings/mapping_q_cache_01.cc
index ded54487d0..7a021b36bb 100644
--- a/tests/mappings/mapping_q_cache_01.cc
+++ b/tests/mappings/mapping_q_cache_01.cc
@@ -44,7 +44,7 @@ do_test(const unsigned int degree)
   for (unsigned int d = 0; d < dim; ++d)
     p2[d] = 0.5;
 
-  deallog << "Testing degree " << degree << " in " << dim << "D" << std::endl;
+  deallog << "Testing degree " << degree << " in " << dim << 'D' << std::endl;
   for (const auto &cell : tria.active_cell_iterators())
     {
       deallog << "cell " << cell->id() << ": "
diff --git a/tests/mappings/mapping_q_cache_02.cc b/tests/mappings/mapping_q_cache_02.cc
index 533fe609f4..fcbf507d66 100644
--- a/tests/mappings/mapping_q_cache_02.cc
+++ b/tests/mappings/mapping_q_cache_02.cc
@@ -49,7 +49,7 @@ do_test(const unsigned int degree)
   for (unsigned int d = 0; d < dim; ++d)
     p2[d] = 0.5;
 
-  deallog << "Testing degree " << degree << " in " << dim << "D" << std::endl;
+  deallog << "Testing degree " << degree << " in " << dim << 'D' << std::endl;
   for (const auto &cell : tria.active_cell_iterators())
     {
       deallog << "cell " << cell->id() << ": "
diff --git a/tests/mappings/mapping_q_cache_03.cc b/tests/mappings/mapping_q_cache_03.cc
index 19a274afec..913b46a5c2 100644
--- a/tests/mappings/mapping_q_cache_03.cc
+++ b/tests/mappings/mapping_q_cache_03.cc
@@ -45,7 +45,7 @@ do_test(const unsigned int degree)
   for (unsigned int d = 0; d < dim; ++d)
     p2[d] = 0.5;
 
-  deallog << "Testing degree " << degree << " in " << dim << "D" << std::endl;
+  deallog << "Testing degree " << degree << " in " << dim << 'D' << std::endl;
   for (const auto &cell : tria.active_cell_iterators())
     {
       deallog << "cell " << cell->id() << ": "
@@ -67,7 +67,7 @@ do_test(const unsigned int degree)
   tria.refine_global(1);
   mapping_cache.initialize(tria, mapping);
 
-  deallog << "Testing degree " << degree << " in " << dim << "D" << std::endl;
+  deallog << "Testing degree " << degree << " in " << dim << 'D' << std::endl;
   for (const auto &cell : tria.active_cell_iterators())
     {
       deallog << "cell " << cell->id() << ": "
diff --git a/tests/mappings/mapping_q_cache_04.cc b/tests/mappings/mapping_q_cache_04.cc
index 2caf2b20fb..5d39148731 100644
--- a/tests/mappings/mapping_q_cache_04.cc
+++ b/tests/mappings/mapping_q_cache_04.cc
@@ -73,7 +73,7 @@ do_test(const unsigned int degree)
   for (unsigned int d = 0; d < dim; ++d)
     p2[d] = 0.5;
 
-  deallog << "Testing degree " << degree << " in " << dim << "D" << std::endl;
+  deallog << "Testing degree " << degree << " in " << dim << 'D' << std::endl;
   for (const auto &cell : tria.cell_iterators())
     {
       deallog << "cell " << cell->id() << ": "
@@ -96,7 +96,7 @@ do_test(const unsigned int degree)
   tria.refine_global(1);
   mapping_cache.initialize(tria, position_lambda);
 
-  deallog << "Testing degree " << degree << " in " << dim << "D" << std::endl;
+  deallog << "Testing degree " << degree << " in " << dim << 'D' << std::endl;
   for (const auto &cell : tria.active_cell_iterators())
     {
       deallog << "cell " << cell->id() << ": "
diff --git a/tests/mappings/mapping_q_cache_08.cc b/tests/mappings/mapping_q_cache_08.cc
index 34ac006251..212a793aa8 100644
--- a/tests/mappings/mapping_q_cache_08.cc
+++ b/tests/mappings/mapping_q_cache_08.cc
@@ -66,7 +66,7 @@ do_test(const unsigned int degree)
 
   mapping_cache.initialize(tria, position_lambda);
 
-  deallog << "Testing degree " << degree << " in " << dim << "D" << std::endl;
+  deallog << "Testing degree " << degree << " in " << dim << 'D' << std::endl;
   for (const auto &cell : tria.cell_iterators())
     {
       deallog << "vertices on cell " << cell->id() << std::endl;
@@ -83,7 +83,7 @@ do_test(const unsigned int degree)
   tria.refine_global(1);
   mapping_cache.initialize(tria, position_lambda);
 
-  deallog << "Testing degree " << degree << " in " << dim << "D" << std::endl;
+  deallog << "Testing degree " << degree << " in " << dim << 'D' << std::endl;
   for (const auto &cell : tria.active_cell_iterators())
     {
       deallog << "vertices on cell " << cell->id() << std::endl;
diff --git a/tests/mappings/mapping_q_eulerian_11.cc b/tests/mappings/mapping_q_eulerian_11.cc
index ffea43045b..55ef95a519 100644
--- a/tests/mappings/mapping_q_eulerian_11.cc
+++ b/tests/mappings/mapping_q_eulerian_11.cc
@@ -128,7 +128,7 @@ test()
 
   for (auto point = active_vertices.begin(); point != active_vertices.end();
        ++point)
-    deallog << point->second << " ";
+    deallog << point->second << ' ';
 
   deallog << std::endl << "Ok." << std::endl;
 }
diff --git a/tests/mappings/mapping_q_eulerian_12.cc b/tests/mappings/mapping_q_eulerian_12.cc
index 6bfb9c9e2c..ed082c2320 100644
--- a/tests/mappings/mapping_q_eulerian_12.cc
+++ b/tests/mappings/mapping_q_eulerian_12.cc
@@ -76,9 +76,9 @@ test()
   for (const auto &cell : dof_handler.active_cell_iterators())
     {
       deallog << "Center: [" << cell->center() << "], with mapping ["
-              << euler.get_center(cell, false) << "]" << std::endl;
+              << euler.get_center(cell, false) << ']' << std::endl;
       deallog << "Center: [" << cell->center() << "], with mapping + flag ["
-              << euler.get_center(cell, true) << "]" << std::endl;
+              << euler.get_center(cell, true) << ']' << std::endl;
     }
 }
 
diff --git a/tests/mappings/mapping_q_eulerian_13.cc b/tests/mappings/mapping_q_eulerian_13.cc
index 6762769a47..f473bd5a08 100644
--- a/tests/mappings/mapping_q_eulerian_13.cc
+++ b/tests/mappings/mapping_q_eulerian_13.cc
@@ -61,7 +61,7 @@ test()
       const auto p1 = cell->bounding_box().get_boundary_points();
       const auto p2 = euler.get_bounding_box(cell).get_boundary_points();
       deallog << "BBox: [" << p1.first << ", " << p1.second
-              << "], with mapping [" << p2.first << ", " << p2.second << "]"
+              << "], with mapping [" << p2.first << ", " << p2.second << ']'
               << std::endl;
     }
 }
diff --git a/tests/matrix_free/advect_1d.cc b/tests/matrix_free/advect_1d.cc
index 85a49103d0..bf4794d714 100644
--- a/tests/matrix_free/advect_1d.cc
+++ b/tests/matrix_free/advect_1d.cc
@@ -305,7 +305,7 @@ test(const unsigned int n_refine)
   out -= in;
 
   double diff_norm = out.linfty_norm();
-  deallog << "Norm of difference:          " << diff_norm << " " << std::endl;
+  deallog << "Norm of difference:          " << diff_norm << ' ' << std::endl;
 }
 
 
diff --git a/tests/matrix_free/advect_1d_system.cc b/tests/matrix_free/advect_1d_system.cc
index 5bd3cec55b..7b1ef0c380 100644
--- a/tests/matrix_free/advect_1d_system.cc
+++ b/tests/matrix_free/advect_1d_system.cc
@@ -314,7 +314,7 @@ test(const unsigned int n_refine)
   out -= in;
 
   double diff_norm = out.linfty_norm();
-  deallog << "Norm of difference:          " << diff_norm << " " << std::endl;
+  deallog << "Norm of difference:          " << diff_norm << ' ' << std::endl;
 }
 
 
diff --git a/tests/matrix_free/advect_1d_vectorization_mask.cc b/tests/matrix_free/advect_1d_vectorization_mask.cc
index 4bc30b163a..9506cc9cb6 100644
--- a/tests/matrix_free/advect_1d_vectorization_mask.cc
+++ b/tests/matrix_free/advect_1d_vectorization_mask.cc
@@ -331,7 +331,7 @@ test(const unsigned int n_refine)
   out -= in;
 
   double diff_norm = out.linfty_norm();
-  deallog << "Norm of difference:          " << diff_norm << " " << std::endl;
+  deallog << "Norm of difference:          " << diff_norm << ' ' << std::endl;
 }
 
 
diff --git a/tests/matrix_free/assemble_matrix_01.cc b/tests/matrix_free/assemble_matrix_01.cc
index ed988e4278..fdbe2b54cc 100644
--- a/tests/matrix_free/assemble_matrix_01.cc
+++ b/tests/matrix_free/assemble_matrix_01.cc
@@ -117,7 +117,7 @@ do_test(const DoFHandler<dim> &dof)
                   fe_eval.begin_dof_values()[j][v];
           }
         test_matrix.add(-1., cell_matrix);
-        deallog << test_matrix.frobenius_norm() << " ";
+        deallog << test_matrix.frobenius_norm() << ' ';
       }
     deallog << std::endl;
   }
diff --git a/tests/matrix_free/assemble_matrix_02.cc b/tests/matrix_free/assemble_matrix_02.cc
index 9ae31982f8..4f50f0c67b 100644
--- a/tests/matrix_free/assemble_matrix_02.cc
+++ b/tests/matrix_free/assemble_matrix_02.cc
@@ -173,7 +173,7 @@ do_test(const DoFHandler<dim> &dof)
                   phi_u.begin_dof_values()[j][v];
           }
         test_matrix.add(-1., cell_matrix);
-        deallog << test_matrix.frobenius_norm() << " ";
+        deallog << test_matrix.frobenius_norm() << ' ';
       }
     deallog << std::endl;
   }
diff --git a/tests/matrix_free/dg_pbc_02.cc b/tests/matrix_free/dg_pbc_02.cc
index ac0c7e1ba7..bce87ba726 100644
--- a/tests/matrix_free/dg_pbc_02.cc
+++ b/tests/matrix_free/dg_pbc_02.cc
@@ -126,13 +126,13 @@ test()
       deallog << "Level: " << level << std::endl;
       deallog << "Interior faces: ";
       for (unsigned int f = 0; f < n_inner_faces.size(); ++f)
-        deallog << n_inner_faces[f] << " ";
+        deallog << n_inner_faces[f] << ' ';
       deallog << std::endl << "Exterior faces: ";
       for (unsigned int f = 0; f < n_inner_other_faces.size(); ++f)
-        deallog << n_inner_other_faces[f] << " ";
+        deallog << n_inner_other_faces[f] << ' ';
       deallog << std::endl << "Boundary faces: ";
       for (unsigned int f = 0; f < n_boundary_faces.size(); ++f)
-        deallog << n_boundary_faces[f] << " ";
+        deallog << n_boundary_faces[f] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/dof_info_01.cc b/tests/matrix_free/dof_info_01.cc
index 271b8dbc3a..292428ff48 100644
--- a/tests/matrix_free/dof_info_01.cc
+++ b/tests/matrix_free/dof_info_01.cc
@@ -124,7 +124,7 @@ test(const bool adaptive_ref = true)
         my_rows.erase(std::unique(my_rows.begin(), my_rows.end()),
                       my_rows.end());
         for (auto el : my_rows)
-          deallog << " " << el;
+          deallog << ' ' << el;
         deallog << std::endl;
       };
       get_and_log(true);
@@ -166,7 +166,7 @@ test(const bool adaptive_ref = true)
         << "plot '-' using 1:2 with lines notitle, '-' with labels tc rgb 'red' nopoint notitle, '-' with labels point pt 4 offset 1,1 notitle"
         << std::endl;
       GridOut().write_gnuplot(tria, f);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       // output cell blocks:
       for (unsigned int cell = 0; cell < n_cells; ++cell)
@@ -177,11 +177,11 @@ test(const bool adaptive_ref = true)
           }
 
       f << std::flush;
-      f << "e" << std::endl << std::endl;
+      f << 'e' << std::endl << std::endl;
 
       DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
 
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
     }
 }
 
diff --git a/tests/matrix_free/dof_info_02.cc b/tests/matrix_free/dof_info_02.cc
index e7d523dfb7..2a515f7d2d 100644
--- a/tests/matrix_free/dof_info_02.cc
+++ b/tests/matrix_free/dof_info_02.cc
@@ -126,7 +126,7 @@ test(const bool adaptive_ref = true)
         my_rows.erase(std::unique(my_rows.begin(), my_rows.end()),
                       my_rows.end());
         for (auto el : my_rows)
-          deallog << " " << el;
+          deallog << ' ' << el;
         deallog << std::endl;
       };
       get_and_log(true);
@@ -168,7 +168,7 @@ test(const bool adaptive_ref = true)
         << "plot '-' using 1:2 with lines notitle, '-' with labels tc rgb 'red' nopoint notitle, '-' with labels point pt 4 offset 1,1 notitle"
         << std::endl;
       GridOut().write_gnuplot(tria, f);
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
 
       // output cell blocks:
       for (unsigned int cell = 0; cell < n_cells; ++cell)
@@ -179,11 +179,11 @@ test(const bool adaptive_ref = true)
           }
 
       f << std::flush;
-      f << "e" << std::endl << std::endl;
+      f << 'e' << std::endl << std::endl;
 
       DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
 
-      f << "e" << std::endl;
+      f << 'e' << std::endl;
     }
 }
 
diff --git a/tests/matrix_free/ecl_02.cc b/tests/matrix_free/ecl_02.cc
index 2c6997782b..daa1d26768 100644
--- a/tests/matrix_free/ecl_02.cc
+++ b/tests/matrix_free/ecl_02.cc
@@ -126,22 +126,22 @@ test(const unsigned int n_refinements = 1)
 
               for (unsigned int i = 0; i < phi_m.static_dofs_per_component; ++i)
                 deallog << static_cast<int>(phi_m.begin_dof_values()[i][0])
-                        << " ";
+                        << ' ';
               deallog << std::endl;
               phi_m.gather_evaluate(src, EvaluationFlags::values);
               for (unsigned int i = 0; i < phi_m.static_n_q_points; ++i)
-                deallog << static_cast<int>(phi_m.begin_values()[i][0]) << " ";
+                deallog << static_cast<int>(phi_m.begin_values()[i][0]) << ' ';
               deallog << std::endl;
 
               phi_p.read_dof_values(src);
               for (unsigned int i = 0; i < phi_p.static_dofs_per_component; ++i)
                 deallog << static_cast<int>(phi_p.begin_dof_values()[i][0])
-                        << " ";
+                        << ' ';
               deallog << std::endl;
 
               phi_p.gather_evaluate(src, EvaluationFlags::values);
               for (unsigned int i = 0; i < phi_p.static_n_q_points; ++i)
-                deallog << static_cast<int>(phi_p.begin_values()[i][0]) << " ";
+                deallog << static_cast<int>(phi_p.begin_values()[i][0]) << ' ';
               deallog << std::endl << std::endl;
             }
         }
diff --git a/tests/matrix_free/evaluate_1d_shape_01.cc b/tests/matrix_free/evaluate_1d_shape_01.cc
index c0f82a5e00..f1679db74a 100644
--- a/tests/matrix_free/evaluate_1d_shape_01.cc
+++ b/tests/matrix_free/evaluate_1d_shape_01.cc
@@ -75,7 +75,7 @@ test()
 
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
-    deallog << y[i] - y_ref[i] << " ";
+    deallog << y[i] - y_ref[i] << ' ';
   deallog << std::endl;
 
 
@@ -101,7 +101,7 @@ test()
 
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
-    deallog << x[i] - x_ref[i] << " ";
+    deallog << x[i] - x_ref[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/matrix_free/evaluate_1d_shape_02.cc b/tests/matrix_free/evaluate_1d_shape_02.cc
index cab21841aa..0154d88a7a 100644
--- a/tests/matrix_free/evaluate_1d_shape_02.cc
+++ b/tests/matrix_free/evaluate_1d_shape_02.cc
@@ -90,7 +90,7 @@ test()
 
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
-    deallog << y[i] - y_ref[i] << " ";
+    deallog << y[i] - y_ref[i] << ' ';
   deallog << std::endl;
 
 
@@ -116,7 +116,7 @@ test()
 
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
-    deallog << x[i] - x_ref[i] << " ";
+    deallog << x[i] - x_ref[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/matrix_free/evaluate_1d_shape_03.cc b/tests/matrix_free/evaluate_1d_shape_03.cc
index c618cb16f0..41a89b8011 100644
--- a/tests/matrix_free/evaluate_1d_shape_03.cc
+++ b/tests/matrix_free/evaluate_1d_shape_03.cc
@@ -73,7 +73,7 @@ test()
 
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
-    deallog << y[i] - y_ref[i] << " ";
+    deallog << y[i] - y_ref[i] << ' ';
   deallog << std::endl;
 
 
@@ -99,7 +99,7 @@ test()
 
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
-    deallog << x[i] - x_ref[i] << " ";
+    deallog << x[i] - x_ref[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/matrix_free/evaluate_1d_shape_04.cc b/tests/matrix_free/evaluate_1d_shape_04.cc
index 723bdfc89e..bc09357d42 100644
--- a/tests/matrix_free/evaluate_1d_shape_04.cc
+++ b/tests/matrix_free/evaluate_1d_shape_04.cc
@@ -59,7 +59,7 @@ test()
 
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
-    deallog << x[i] - y_ref[i] << " ";
+    deallog << x[i] - y_ref[i] << ' ';
   deallog << std::endl;
 
 
@@ -84,7 +84,7 @@ test()
 
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
-    deallog << x[i] - x_ref[i] << " ";
+    deallog << x[i] - x_ref[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/matrix_free/evaluate_1d_shape_05.cc b/tests/matrix_free/evaluate_1d_shape_05.cc
index 3cc4e127ee..d5a6e16e04 100644
--- a/tests/matrix_free/evaluate_1d_shape_05.cc
+++ b/tests/matrix_free/evaluate_1d_shape_05.cc
@@ -89,7 +89,7 @@ test()
 
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
-    deallog << x[i] - y_ref[i] << " ";
+    deallog << x[i] - y_ref[i] << ' ';
   deallog << std::endl;
 
 
@@ -114,7 +114,7 @@ test()
 
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
-    deallog << x[i] - x_ref[i] << " ";
+    deallog << x[i] - x_ref[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/matrix_free/evaluate_1d_shape_06.cc b/tests/matrix_free/evaluate_1d_shape_06.cc
index 222dc42881..3817be34c2 100644
--- a/tests/matrix_free/evaluate_1d_shape_06.cc
+++ b/tests/matrix_free/evaluate_1d_shape_06.cc
@@ -71,7 +71,7 @@ test()
 
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
-    deallog << x[i] - y_ref[i] << " ";
+    deallog << x[i] - y_ref[i] << ' ';
   deallog << std::endl;
 
 
@@ -96,7 +96,7 @@ test()
 
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
-    deallog << x[i] - x_ref[i] << " ";
+    deallog << x[i] - x_ref[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/matrix_free/evaluate_1d_shape_07.cc b/tests/matrix_free/evaluate_1d_shape_07.cc
index 7253063fcf..6e94b202a0 100644
--- a/tests/matrix_free/evaluate_1d_shape_07.cc
+++ b/tests/matrix_free/evaluate_1d_shape_07.cc
@@ -70,7 +70,7 @@ test()
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
     {
-      deallog << y[i][0] - y_ref[i][0] << " ";
+      deallog << y[i][0] - y_ref[i][0] << ' ';
       for (unsigned int v = 1; v < VectorizedArray<double>::size(); ++v)
         AssertThrow(std::abs(y[i][v] - y_ref[i][v]) < 1e-12,
                     ExcInternalError());
@@ -102,7 +102,7 @@ test()
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
     {
-      deallog << x[i][0] - x_ref[i][0] << " ";
+      deallog << x[i][0] - x_ref[i][0] << ' ';
       for (unsigned int v = 1; v < VectorizedArray<double>::size(); ++v)
         AssertThrow(std::abs(x[i][v] - x_ref[i][v]) < 1e-12,
                     ExcInternalError());
diff --git a/tests/matrix_free/evaluate_1d_shape_08.cc b/tests/matrix_free/evaluate_1d_shape_08.cc
index 657472fc6f..3b3542416a 100644
--- a/tests/matrix_free/evaluate_1d_shape_08.cc
+++ b/tests/matrix_free/evaluate_1d_shape_08.cc
@@ -99,7 +99,7 @@ test()
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
     {
-      deallog << y[i][0] - y_ref[i][0] << " ";
+      deallog << y[i][0] - y_ref[i][0] << ' ';
       for (unsigned int v = 1; v < VectorizedArray<double>::size(); ++v)
         AssertThrow(std::abs(y[i][v] - y_ref[i][v]) < 1e-12,
                     ExcInternalError());
@@ -130,7 +130,7 @@ test()
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
     {
-      deallog << x[i][0] - x_ref[i][0] << " ";
+      deallog << x[i][0] - x_ref[i][0] << ' ';
       for (unsigned int v = 1; v < VectorizedArray<double>::size(); ++v)
         AssertThrow(std::abs(x[i][v] - x_ref[i][v]) < 1e-12,
                     ExcInternalError());
diff --git a/tests/matrix_free/evaluate_1d_shape_09.cc b/tests/matrix_free/evaluate_1d_shape_09.cc
index 2020842420..f5e741a95a 100644
--- a/tests/matrix_free/evaluate_1d_shape_09.cc
+++ b/tests/matrix_free/evaluate_1d_shape_09.cc
@@ -78,7 +78,7 @@ test()
   deallog << "Errors no transpose: ";
   for (unsigned int i = 0; i < M; ++i)
     {
-      deallog << y[i][0] - y_ref[i][0] << " ";
+      deallog << y[i][0] - y_ref[i][0] << ' ';
       for (unsigned int v = 1; v < VectorizedArray<double>::size(); ++v)
         AssertThrow(std::abs(y[i][v] - y_ref[i][v]) < 1e-12,
                     ExcInternalError());
@@ -110,7 +110,7 @@ test()
   deallog << "Errors transpose:    ";
   for (unsigned int i = 0; i < N; ++i)
     {
-      deallog << x[i][0] - x_ref[i][0] << " ";
+      deallog << x[i][0] - x_ref[i][0] << ' ';
       for (unsigned int v = 1; v < VectorizedArray<double>::size(); ++v)
         AssertThrow(std::abs(x[i][v] - x_ref[i][v]) < 1e-12,
                     ExcInternalError());
diff --git a/tests/matrix_free/faces_value_optimization.cc b/tests/matrix_free/faces_value_optimization.cc
index 46fab35f28..bcd2721120 100644
--- a/tests/matrix_free/faces_value_optimization.cc
+++ b/tests/matrix_free/faces_value_optimization.cc
@@ -93,19 +93,19 @@ private:
                 if (std::abs(diff[v]) > 1e-12)
                   {
                     deallog << "Error detected on interior face " << face
-                            << ", v=" << v << ", q=" << q << "!" << std::endl;
+                            << ", v=" << v << ", q=" << q << '!' << std::endl;
                     deallog << "ref: ";
                     for (unsigned int i = 0; i < ref.dofs_per_cell; ++i)
-                      deallog << ref.get_dof_value(i)[v] << " ";
+                      deallog << ref.get_dof_value(i)[v] << ' ';
                     deallog << std::endl;
                     deallog << "done: " << check.get_value(q)[v]
                             << " instead of " << ref.get_value(q)[v]
                             << std::endl;
 
                     deallog
-                      << data.get_face_info(face).cells_interior[v] << " "
-                      << (int)data.get_face_info(face).interior_face_no << " "
-                      << (int)data.get_face_info(face).face_orientation << " "
+                      << data.get_face_info(face).cells_interior[v] << ' '
+                      << (int)data.get_face_info(face).interior_face_no << ' '
+                      << (int)data.get_face_info(face).face_orientation << ' '
                       << (int)data.get_face_info(face).subface_index
                       << std::endl;
                     deallog << std::endl;
@@ -141,19 +141,19 @@ private:
                 if (std::abs(diff[v]) > 1e-12)
                   {
                     deallog << "Error detected on exterior face " << face
-                            << ", v=" << v << ", q=" << q << "!" << std::endl;
+                            << ", v=" << v << ", q=" << q << '!' << std::endl;
                     deallog << "ref: ";
                     for (unsigned int i = 0; i < ref.dofs_per_cell; ++i)
-                      deallog << refr.get_dof_value(i)[v] << " ";
+                      deallog << refr.get_dof_value(i)[v] << ' ';
                     deallog << std::endl;
                     deallog << "done: " << checkr.get_value(q)[v]
                             << " instead of " << refr.get_value(q)[v]
                             << std::endl;
 
                     deallog
-                      << data.get_face_info(face).cells_exterior[v] << " "
-                      << (int)data.get_face_info(face).exterior_face_no << " "
-                      << (int)data.get_face_info(face).face_orientation << " "
+                      << data.get_face_info(face).cells_exterior[v] << ' '
+                      << (int)data.get_face_info(face).exterior_face_no << ' '
+                      << (int)data.get_face_info(face).face_orientation << ' '
                       << (int)data.get_face_info(face).subface_index
                       << std::endl;
                     deallog << std::endl;
diff --git a/tests/matrix_free/faces_value_optimization_02.cc b/tests/matrix_free/faces_value_optimization_02.cc
index a57f20a7b4..cb1dd4ab84 100644
--- a/tests/matrix_free/faces_value_optimization_02.cc
+++ b/tests/matrix_free/faces_value_optimization_02.cc
@@ -93,19 +93,19 @@ private:
                 if (std::abs(diff[v]) > 1e-12)
                   {
                     deallog << "Error detected on face" << face << ", v=" << v
-                            << "!" << std::endl;
+                            << '!' << std::endl;
                     deallog << "ref: ";
                     for (unsigned int i = 0; i < ref.dofs_per_cell; ++i)
-                      deallog << ref.get_dof_value(i)[v] << " ";
+                      deallog << ref.get_dof_value(i)[v] << ' ';
                     deallog << std::endl;
                     deallog << "done: " << check.get_value(q)[v]
                             << " instead of " << ref.get_value(q)[v]
                             << std::endl;
 
                     deallog
-                      << data.get_face_info(face).cells_interior[v] << " "
-                      << (int)data.get_face_info(face).interior_face_no << " "
-                      << (int)data.get_face_info(face).face_orientation << " "
+                      << data.get_face_info(face).cells_interior[v] << ' '
+                      << (int)data.get_face_info(face).interior_face_no << ' '
+                      << (int)data.get_face_info(face).face_orientation << ' '
                       << (int)data.get_face_info(face).subface_index
                       << std::endl;
                     deallog << std::endl;
@@ -141,19 +141,19 @@ private:
                 if (std::abs(diff[v]) > 1e-12)
                   {
                     deallog << "Error detected on face" << face << ", v=" << v
-                            << "!" << std::endl;
+                            << '!' << std::endl;
                     deallog << "ref: ";
                     for (unsigned int i = 0; i < ref.dofs_per_cell; ++i)
-                      deallog << refr.get_dof_value(i)[v] << " ";
+                      deallog << refr.get_dof_value(i)[v] << ' ';
                     deallog << std::endl;
                     deallog << "done: " << check.get_value(q)[v]
                             << " instead of " << ref.get_value(q)[v]
                             << std::endl;
 
                     deallog
-                      << data.get_face_info(face).cells_exterior[v] << " "
-                      << (int)data.get_face_info(face).exterior_face_no << " "
-                      << (int)data.get_face_info(face).face_orientation << " "
+                      << data.get_face_info(face).cells_exterior[v] << ' '
+                      << (int)data.get_face_info(face).exterior_face_no << ' '
+                      << (int)data.get_face_info(face).face_orientation << ' '
                       << (int)data.get_face_info(face).subface_index
                       << std::endl;
                     deallog << std::endl;
diff --git a/tests/matrix_free/faces_value_optimization_03.cc b/tests/matrix_free/faces_value_optimization_03.cc
index d7697fa589..ce3224c6c6 100644
--- a/tests/matrix_free/faces_value_optimization_03.cc
+++ b/tests/matrix_free/faces_value_optimization_03.cc
@@ -96,19 +96,19 @@ private:
                 if (std::abs(diff[v]) > 1e-12)
                   {
                     deallog << "Error detected on interior face " << face
-                            << ", v=" << v << ", q=" << q << "!" << std::endl;
+                            << ", v=" << v << ", q=" << q << '!' << std::endl;
                     deallog << "ref: ";
                     for (unsigned int i = 0; i < ref.dofs_per_cell; ++i)
-                      deallog << ref.get_dof_value(i)[v] << " ";
+                      deallog << ref.get_dof_value(i)[v] << ' ';
                     deallog << std::endl;
                     deallog << "done: " << check.get_value(q)[v]
                             << " instead of " << ref.get_value(q)[v]
                             << std::endl;
 
                     deallog
-                      << data.get_face_info(face).cells_interior[v] << " "
-                      << (int)data.get_face_info(face).interior_face_no << " "
-                      << (int)data.get_face_info(face).face_orientation << " "
+                      << data.get_face_info(face).cells_interior[v] << ' '
+                      << (int)data.get_face_info(face).interior_face_no << ' '
+                      << (int)data.get_face_info(face).face_orientation << ' '
                       << (int)data.get_face_info(face).subface_index
                       << std::endl;
                     deallog << std::endl;
@@ -144,19 +144,19 @@ private:
                 if (std::abs(diff[v]) > 1e-12)
                   {
                     deallog << "Error detected on exterior face " << face
-                            << ", v=" << v << ", q=" << q << "!" << std::endl;
+                            << ", v=" << v << ", q=" << q << '!' << std::endl;
                     deallog << "ref: ";
                     for (unsigned int i = 0; i < ref.dofs_per_cell; ++i)
-                      deallog << refr.get_dof_value(i)[v] << " ";
+                      deallog << refr.get_dof_value(i)[v] << ' ';
                     deallog << std::endl;
                     deallog << "done: " << checkr.get_value(q)[v]
                             << " instead of " << refr.get_value(q)[v]
                             << std::endl;
 
                     deallog
-                      << data.get_face_info(face).cells_exterior[v] << " "
-                      << (int)data.get_face_info(face).exterior_face_no << " "
-                      << (int)data.get_face_info(face).face_orientation << " "
+                      << data.get_face_info(face).cells_exterior[v] << ' '
+                      << (int)data.get_face_info(face).exterior_face_no << ' '
+                      << (int)data.get_face_info(face).face_orientation << ' '
                       << (int)data.get_face_info(face).subface_index
                       << std::endl;
                     deallog << std::endl;
diff --git a/tests/matrix_free/fe_evaluation_print_01.cc b/tests/matrix_free/fe_evaluation_print_01.cc
index c8a9838d0f..d14979ec01 100644
--- a/tests/matrix_free/fe_evaluation_print_01.cc
+++ b/tests/matrix_free/fe_evaluation_print_01.cc
@@ -40,7 +40,7 @@ test()
     {
       for (unsigned int j = 1; j < 25; ++j)
         if (FEEvaluation<dim, -1, 0, 1>::fast_evaluation_supported(i, j))
-          deallog << 1 << " ";
+          deallog << 1 << ' ';
         else
           deallog << "  ";
       deallog << std::endl;
@@ -49,7 +49,7 @@ test()
     {
       for (unsigned int j = 1; j < 25; ++j)
         if (FEFaceEvaluation<dim, -1, 0, 1>::fast_evaluation_supported(i, j))
-          deallog << 1 << " ";
+          deallog << 1 << ' ';
         else
           deallog << "  ";
       deallog << std::endl;
diff --git a/tests/matrix_free/get_functions_faces.cc b/tests/matrix_free/get_functions_faces.cc
index 784f7e6638..7fee6b5185 100644
--- a/tests/matrix_free/get_functions_faces.cc
+++ b/tests/matrix_free/get_functions_faces.cc
@@ -82,7 +82,7 @@ private:
         deallog << "Face " << face << ": ";
         for (unsigned int q = 0; q < fe_eval.n_q_points; ++q)
           {
-            deallog << fe_eval.get_value(q)[0] << " "
+            deallog << fe_eval.get_value(q)[0] << ' '
                     << fe_eval.get_normal_derivative(q)[0] << "   ";
           }
         deallog << std::endl;
diff --git a/tests/matrix_free/hanging_node_kernels_01.cc b/tests/matrix_free/hanging_node_kernels_01.cc
index f26e597bf0..da65765ed6 100644
--- a/tests/matrix_free/hanging_node_kernels_01.cc
+++ b/tests/matrix_free/hanging_node_kernels_01.cc
@@ -471,7 +471,7 @@ test(const unsigned int                                           degree,
         }
 
       for (const auto i : values1)
-        deallog << i[0] << " ";
+        deallog << i[0] << ' ';
       deallog << std::endl;
 
       internal::FEEvaluationImplHangingNodesReference<
@@ -483,11 +483,11 @@ test(const unsigned int                                           degree,
           1, eval.get_shape_info(), b == 1, cmask, values2.data());
 
       for (const auto i : values1)
-        deallog << i[0] << " ";
+        deallog << i[0] << ' ';
       deallog << std::endl;
 
       for (const auto i : values2)
-        deallog << i[0] << " ";
+        deallog << i[0] << ' ';
       deallog << std::endl;
       deallog << std::endl;
 
diff --git a/tests/matrix_free/interpolate_to_mg.cc b/tests/matrix_free/interpolate_to_mg.cc
index f09b570b0c..6efb5e2967 100644
--- a/tests/matrix_free/interpolate_to_mg.cc
+++ b/tests/matrix_free/interpolate_to_mg.cc
@@ -234,14 +234,14 @@ test(const unsigned int n_glob_ref = 2, const unsigned int n_ref = 0)
                   {
                     std::cout << "dofs: ";
                     for (const auto i : dof_indices)
-                      std::cout << i << " ";
+                      std::cout << i << ' ';
                     std::cout << std::endl << "values: ";
                     std::vector<LevelNumberType> local_values(
                       dof_indices.size());
                     level_projection[level].extract_subvector_to(dof_indices,
                                                                  local_values);
                     for (const auto v : local_values)
-                      std::cout << v << " ";
+                      std::cout << v << ' ';
                     std::cout << std::endl
                               << "val(q)=" << q_values[q] << std::endl;
                     std::cout << "MGTransfer indices:" << std::endl;
diff --git a/tests/matrix_free/iterators.cc b/tests/matrix_free/iterators.cc
index fd916b4fbf..3064d205ee 100644
--- a/tests/matrix_free/iterators.cc
+++ b/tests/matrix_free/iterators.cc
@@ -75,7 +75,7 @@ public:
           deallog << "Active level (with max_level="
                   << tria.n_global_levels() - 1 << "):" << std::endl;
         else
-          deallog << "Multigrid level " << level << ":" << std::endl;
+          deallog << "Multigrid level " << level << ':' << std::endl;
 
         AffineConstraints<Number> constraint;
 
@@ -108,7 +108,7 @@ public:
           deallog << "cell:      " << cell.to_string() << std::endl;
 
         for (const auto &face : faces)
-          deallog << "face:      " << face.first.to_string() << " "
+          deallog << "face:      " << face.first.to_string() << ' '
                   << face.second.to_string() << std::endl;
 
         for (const auto boundary : boundaries)
diff --git a/tests/matrix_free/matrix_vector_11.cc b/tests/matrix_free/matrix_vector_11.cc
index 320eb83508..8a1a1ef34d 100644
--- a/tests/matrix_free/matrix_vector_11.cc
+++ b/tests/matrix_free/matrix_vector_11.cc
@@ -173,7 +173,7 @@ test()
           mf.vmult(out, in);
           out -= ref;
           const double diff_norm = out.linfty_norm();
-          deallog << " " << diff_norm;
+          deallog << ' ' << diff_norm;
         }
       deallog << std::endl;
     }
diff --git a/tests/matrix_free/matrix_vector_12.cc b/tests/matrix_free/matrix_vector_12.cc
index 15eef59b6d..4625a36a23 100644
--- a/tests/matrix_free/matrix_vector_12.cc
+++ b/tests/matrix_free/matrix_vector_12.cc
@@ -264,7 +264,7 @@ test()
       sparse_matrix.vmult(ref, in[i]);
       out[i] -= ref;
       const double diff_norm = out[i].linfty_norm();
-      deallog << diff_norm << " ";
+      deallog << diff_norm << ' ';
     }
   deallog << std::endl << std::endl;
 }
diff --git a/tests/matrix_free/matrix_vector_13.cc b/tests/matrix_free/matrix_vector_13.cc
index d08b7fe410..8631dde8e4 100644
--- a/tests/matrix_free/matrix_vector_13.cc
+++ b/tests/matrix_free/matrix_vector_13.cc
@@ -260,7 +260,7 @@ test()
       sparse_matrix.vmult(ref, in.block(i));
       out.block(i) -= ref;
       const double diff_norm = out.block(i).linfty_norm();
-      deallog << diff_norm << " ";
+      deallog << diff_norm << ' ';
     }
   deallog << std::endl << std::endl;
 }
diff --git a/tests/matrix_free/matrix_vector_20.cc b/tests/matrix_free/matrix_vector_20.cc
index f2b33b9f98..61a0e275a5 100644
--- a/tests/matrix_free/matrix_vector_20.cc
+++ b/tests/matrix_free/matrix_vector_20.cc
@@ -263,7 +263,7 @@ test()
       sparse_matrix.vmult(ref, in.block(i));
       out.block(i) -= ref;
       const double diff_norm = out.block(i).linfty_norm();
-      deallog << diff_norm << " ";
+      deallog << diff_norm << ' ';
     }
   deallog << std::endl << std::endl;
 }
diff --git a/tests/matrix_free/matrix_vector_21.cc b/tests/matrix_free/matrix_vector_21.cc
index 37ca2a7d32..59ed83b479 100644
--- a/tests/matrix_free/matrix_vector_21.cc
+++ b/tests/matrix_free/matrix_vector_21.cc
@@ -253,7 +253,7 @@ test()
       sparse_matrix.vmult(ref, in.block(i));
       out.block(i) -= ref;
       const double diff_norm = out.block(i).linfty_norm();
-      deallog << diff_norm << " ";
+      deallog << diff_norm << ' ';
     }
   deallog << std::endl << std::endl;
 }
diff --git a/tests/matrix_free/matrix_vector_22.cc b/tests/matrix_free/matrix_vector_22.cc
index 06dcf7cf38..7ba7e51665 100644
--- a/tests/matrix_free/matrix_vector_22.cc
+++ b/tests/matrix_free/matrix_vector_22.cc
@@ -271,7 +271,7 @@ test()
       sparse_matrix.vmult(ref, in[i]);
       out[i] -= ref;
       const double diff_norm = out[i].linfty_norm();
-      deallog << diff_norm << " ";
+      deallog << diff_norm << ' ';
     }
   deallog << std::endl << std::endl;
 }
diff --git a/tests/matrix_free/matrix_vector_23.cc b/tests/matrix_free/matrix_vector_23.cc
index 14cff244ad..9b96740c1d 100644
--- a/tests/matrix_free/matrix_vector_23.cc
+++ b/tests/matrix_free/matrix_vector_23.cc
@@ -285,7 +285,7 @@ test()
       sparse_matrix.vmult(ref, in[i]);
       out[i] -= ref;
       const double diff_norm = out[i].linfty_norm();
-      deallog << diff_norm << " ";
+      deallog << diff_norm << ' ';
     }
   deallog << std::endl << std::endl;
 }
diff --git a/tests/matrix_free/matrix_vector_blocks.cc b/tests/matrix_free/matrix_vector_blocks.cc
index f93dc46bc8..2fee35a7c9 100644
--- a/tests/matrix_free/matrix_vector_blocks.cc
+++ b/tests/matrix_free/matrix_vector_blocks.cc
@@ -214,7 +214,7 @@ test()
 
           out -= ref;
           const double diff_norm = out.linfty_norm();
-          deallog << " " << diff_norm;
+          deallog << ' ' << diff_norm;
         }
       deallog << std::endl;
     }
diff --git a/tests/matrix_free/matrix_vector_faces_13.cc b/tests/matrix_free/matrix_vector_faces_13.cc
index 7d53242f11..df37d8a8cc 100644
--- a/tests/matrix_free/matrix_vector_faces_13.cc
+++ b/tests/matrix_free/matrix_vector_faces_13.cc
@@ -128,7 +128,7 @@ test()
   out_dist -= out;
 
   double diff_norm = out_dist.linfty_norm() / out.linfty_norm();
-  deallog << "Norm of difference:          " << diff_norm << " ";
+  deallog << "Norm of difference:          " << diff_norm << ' ';
 
   // test again, now doing matrix-vector product twice
   mf2.vmult(out_dist, in);
diff --git a/tests/matrix_free/matrix_vector_faces_14.cc b/tests/matrix_free/matrix_vector_faces_14.cc
index c620a04a48..99423b0d3e 100644
--- a/tests/matrix_free/matrix_vector_faces_14.cc
+++ b/tests/matrix_free/matrix_vector_faces_14.cc
@@ -134,7 +134,7 @@ test()
       out_dist -= out;
 
       double diff_norm = out_dist.linfty_norm() / out.linfty_norm();
-      deallog << "Norm of difference:          " << diff_norm << " ";
+      deallog << "Norm of difference:          " << diff_norm << ' ';
 
       // test again, now doing matrix-vector product twice
       mf2.vmult(out_dist, in);
diff --git a/tests/matrix_free/matrix_vector_faces_15.cc b/tests/matrix_free/matrix_vector_faces_15.cc
index d214c47005..c00e458982 100644
--- a/tests/matrix_free/matrix_vector_faces_15.cc
+++ b/tests/matrix_free/matrix_vector_faces_15.cc
@@ -140,7 +140,7 @@ test()
     out(renumbering[i]) -= out_orig.local_element(i);
 
   double diff_norm = out.linfty_norm() / out_orig.linfty_norm();
-  deallog << "Norm of difference:          " << diff_norm << " ";
+  deallog << "Norm of difference:          " << diff_norm << ' ';
 
   // test again, now doing matrix-vector product twice
   mf2.vmult(out, in);
diff --git a/tests/matrix_free/matrix_vector_faces_17.cc b/tests/matrix_free/matrix_vector_faces_17.cc
index 4072f3cf2a..9fa470e3d8 100644
--- a/tests/matrix_free/matrix_vector_faces_17.cc
+++ b/tests/matrix_free/matrix_vector_faces_17.cc
@@ -135,7 +135,7 @@ test()
     out(renumbering[i]) -= out_orig.local_element(i);
 
   double diff_norm = out.linfty_norm() / out_orig.linfty_norm();
-  deallog << "Norm of difference:          " << diff_norm << " ";
+  deallog << "Norm of difference:          " << diff_norm << ' ';
 
   // test again, now doing matrix-vector product twice
   mf2.vmult(out, in);
diff --git a/tests/matrix_free/matrix_vector_faces_18.cc b/tests/matrix_free/matrix_vector_faces_18.cc
index 9b3f17a1ba..7029f50c77 100644
--- a/tests/matrix_free/matrix_vector_faces_18.cc
+++ b/tests/matrix_free/matrix_vector_faces_18.cc
@@ -227,7 +227,7 @@ test()
     out(renumbering[i]) -= out_orig.local_element(i);
 
   double diff_norm = out.linfty_norm() / out_orig.linfty_norm();
-  deallog << "Norm of difference:          " << diff_norm << " ";
+  deallog << "Norm of difference:          " << diff_norm << ' ';
 
   // test again, now doing matrix-vector product twice
   mf2.vmult(out, in);
diff --git a/tests/matrix_free/matrix_vector_faces_19.cc b/tests/matrix_free/matrix_vector_faces_19.cc
index 17a31512da..d7abe20401 100644
--- a/tests/matrix_free/matrix_vector_faces_19.cc
+++ b/tests/matrix_free/matrix_vector_faces_19.cc
@@ -129,7 +129,7 @@ test()
   out_dist -= out;
 
   double diff_norm = out_dist.linfty_norm() / out.linfty_norm();
-  deallog << "Norm of difference:          " << diff_norm << " ";
+  deallog << "Norm of difference:          " << diff_norm << ' ';
 
   // test again, now doing a matrix-vector product and then an add, which
   // should give twice the reference result
diff --git a/tests/matrix_free/matrix_vector_faces_29.cc b/tests/matrix_free/matrix_vector_faces_29.cc
index 5187c374fa..d6e716070b 100644
--- a/tests/matrix_free/matrix_vector_faces_29.cc
+++ b/tests/matrix_free/matrix_vector_faces_29.cc
@@ -136,7 +136,7 @@ test()
       out_dist -= out;
 
       double diff_norm = out_dist.linfty_norm() / out.linfty_norm();
-      deallog << "Norm of difference:          " << diff_norm << " ";
+      deallog << "Norm of difference:          " << diff_norm << ' ';
 
       // test again, now doing matrix-vector product twice
       mf2.vmult(out_dist, in);
diff --git a/tests/matrix_free/matrix_vector_hessians_cells.cc b/tests/matrix_free/matrix_vector_hessians_cells.cc
index 9c8be022a9..341bfb6361 100644
--- a/tests/matrix_free/matrix_vector_hessians_cells.cc
+++ b/tests/matrix_free/matrix_vector_hessians_cells.cc
@@ -208,12 +208,12 @@ test_hessians(const dealii::FE_Poly<dim> &                   fe,
 
   deallog << "dst FEE: ";
   for (unsigned int i = 0; i < end_of_print_dst; ++i)
-    deallog << dst[i] << " ";
+    deallog << dst[i] << ' ';
   deallog << std::endl;
 
   deallog << "dst FEV: ";
   for (unsigned int i = 0; i < end_of_print_dst; ++i)
-    deallog << dst2[i] << " ";
+    deallog << dst2[i] << ' ';
   deallog << std::endl;
 
   // compare solutions of matrix vector product
diff --git a/tests/matrix_free/matrix_vector_hessians_faces.cc b/tests/matrix_free/matrix_vector_hessians_faces.cc
index 5aff3b6642..b191a77492 100644
--- a/tests/matrix_free/matrix_vector_hessians_faces.cc
+++ b/tests/matrix_free/matrix_vector_hessians_faces.cc
@@ -322,12 +322,12 @@ test_hessians(const unsigned int                             degree,
 
   deallog << "dst FEE: ";
   for (unsigned int i = 0; i < end_of_print_dst; ++i)
-    deallog << dst[i] << " ";
+    deallog << dst[i] << ' ';
   deallog << std::endl;
 
   deallog << "dst FEV: ";
   for (unsigned int i = 0; i < end_of_print_dst; ++i)
-    deallog << dst2[i] << " ";
+    deallog << dst2[i] << ' ';
   deallog << std::endl;
 
   // compare solutions of matrix vector product
diff --git a/tests/matrix_free/matrix_vector_hessians_general_cells.cc b/tests/matrix_free/matrix_vector_hessians_general_cells.cc
index 5238c9c20a..a18d7318bb 100644
--- a/tests/matrix_free/matrix_vector_hessians_general_cells.cc
+++ b/tests/matrix_free/matrix_vector_hessians_general_cells.cc
@@ -211,12 +211,12 @@ test_hessians(const dealii::FE_Poly<dim> &                   fe,
 
   deallog << "dst FEE: ";
   for (unsigned int i = 0; i < end_of_print_dst; ++i)
-    deallog << dst[i] << " ";
+    deallog << dst[i] << ' ';
   deallog << std::endl;
 
   deallog << "dst FEV: ";
   for (unsigned int i = 0; i < end_of_print_dst; ++i)
-    deallog << dst2[i] << " ";
+    deallog << dst2[i] << ' ';
   deallog << std::endl;
 
   // compare solutions of matrix vector product
diff --git a/tests/matrix_free/matrix_vector_hessians_general_faces.cc b/tests/matrix_free/matrix_vector_hessians_general_faces.cc
index 0144c098fc..6133bc700a 100644
--- a/tests/matrix_free/matrix_vector_hessians_general_faces.cc
+++ b/tests/matrix_free/matrix_vector_hessians_general_faces.cc
@@ -297,12 +297,12 @@ test_hessians(const unsigned int                             degree,
 
   deallog << "dst FEE: ";
   for (unsigned int i = 0; i < end_of_print_dst; ++i)
-    deallog << dst[i] << " ";
+    deallog << dst[i] << ' ';
   deallog << std::endl;
 
   deallog << "dst FEV: ";
   for (unsigned int i = 0; i < end_of_print_dst; ++i)
-    deallog << dst2[i] << " ";
+    deallog << dst2[i] << ' ';
   deallog << std::endl;
 
   // compare solutions of matrix vector product
diff --git a/tests/matrix_free/matrix_vector_large_degree_03.cc b/tests/matrix_free/matrix_vector_large_degree_03.cc
index 8279c684ce..24260185eb 100644
--- a/tests/matrix_free/matrix_vector_large_degree_03.cc
+++ b/tests/matrix_free/matrix_vector_large_degree_03.cc
@@ -89,7 +89,7 @@ test()
       mf_data);
     mf.vmult(out, in);
     out -= ref;
-    deallog << "Error with " << fe_degree + 2 << "^" << dim
+    deallog << "Error with " << fe_degree + 2 << '^' << dim
             << " quadrature points: " << out.l2_norm() << std::endl;
   }
 
@@ -100,7 +100,7 @@ test()
     MatrixFreeTest<dim, fe_degree, double, Vector<double>, 100> mf(mf_data);
     mf.vmult(out, in);
     out -= ref;
-    deallog << "Error with " << 100 << "^" << dim
+    deallog << "Error with " << 100 << '^' << dim
             << " quadrature points: " << out.l2_norm() << std::endl;
   }
   {
@@ -108,7 +108,7 @@ test()
     MatrixFreeTest<dim, fe_degree, double, Vector<double>, 200> mf(mf_data);
     mf.vmult(out, in);
     out -= ref;
-    deallog << "Error with " << 200 << "^" << dim
+    deallog << "Error with " << 200 << '^' << dim
             << " quadrature points: " << out.l2_norm() << std::endl;
   }
   {
@@ -116,7 +116,7 @@ test()
     MatrixFreeTest<dim, fe_degree, double, Vector<double>, 500> mf(mf_data);
     mf.vmult(out, in);
     out -= ref;
-    deallog << "Error with " << 500 << "^" << dim
+    deallog << "Error with " << 500 << '^' << dim
             << " quadrature points: " << out.l2_norm() << std::endl;
   }
   {
@@ -124,7 +124,7 @@ test()
     MatrixFreeTest<dim, fe_degree, double, Vector<double>, 1000> mf(mf_data);
     mf.vmult(out, in);
     out -= ref;
-    deallog << "Error with " << 1000 << "^" << dim
+    deallog << "Error with " << 1000 << '^' << dim
             << " quadrature points: " << out.l2_norm() << std::endl;
   }
 }
diff --git a/tests/matrix_free/mixed_mesh_hn_algorithm_01.cc b/tests/matrix_free/mixed_mesh_hn_algorithm_01.cc
index 61903625b0..6a73585ea9 100644
--- a/tests/matrix_free/mixed_mesh_hn_algorithm_01.cc
+++ b/tests/matrix_free/mixed_mesh_hn_algorithm_01.cc
@@ -127,7 +127,7 @@ main()
              i < matrix_free.get_dof_info(0).row_starts[c + 1].first;
              ++i)
           deallog << std::setw(3) << matrix_free.get_dof_info(0).dof_indices[i]
-                  << " ";
+                  << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
diff --git a/tests/matrix_free/partitioner_01.cc b/tests/matrix_free/partitioner_01.cc
index de2bb281fa..c48e6eb6a9 100644
--- a/tests/matrix_free/partitioner_01.cc
+++ b/tests/matrix_free/partitioner_01.cc
@@ -156,7 +156,7 @@ private:
          i++)
       dst.begin()[i] = 0;
     for (unsigned int i = 0; i < 2 * Utilities::pow(fe_degree + 1, dim); ++i)
-      deallog << static_cast<int>(dst[i]) << " ";
+      deallog << static_cast<int>(dst[i]) << ' ';
     deallog << std::endl << std::endl;
   }
 
@@ -168,7 +168,7 @@ private:
   {
     deallog << "src:" << std::endl;
     for (unsigned int i = 0; i < 2 * Utilities::pow(fe_degree + 1, dim); ++i)
-      deallog << static_cast<int>(src[i]) << " ";
+      deallog << static_cast<int>(src[i]) << ' ';
     deallog << std::endl;
 
     for (unsigned int i = Utilities::pow(fe_degree + 1, dim);
diff --git a/tests/matrix_free/point_evaluation_01.cc b/tests/matrix_free/point_evaluation_01.cc
index ab6d385049..d2970048aa 100644
--- a/tests/matrix_free/point_evaluation_01.cc
+++ b/tests/matrix_free/point_evaluation_01.cc
@@ -129,7 +129,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << factor_float * i << " ";
+        deallog << factor_float * i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_02.cc b/tests/matrix_free/point_evaluation_02.cc
index 9feca85fbe..a6e142517f 100644
--- a/tests/matrix_free/point_evaluation_02.cc
+++ b/tests/matrix_free/point_evaluation_02.cc
@@ -122,7 +122,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_03.cc b/tests/matrix_free/point_evaluation_03.cc
index 2b573ea9d8..e31ad98948 100644
--- a/tests/matrix_free/point_evaluation_03.cc
+++ b/tests/matrix_free/point_evaluation_03.cc
@@ -138,7 +138,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_04.cc b/tests/matrix_free/point_evaluation_04.cc
index 3399d4af81..43c9312d23 100644
--- a/tests/matrix_free/point_evaluation_04.cc
+++ b/tests/matrix_free/point_evaluation_04.cc
@@ -165,7 +165,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
 
       evaluator_scalar.integrate(solution_values,
@@ -173,7 +173,7 @@ test(const unsigned int degree)
                                    EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_05.cc b/tests/matrix_free/point_evaluation_05.cc
index 9cf98f4d5d..4fc2221c62 100644
--- a/tests/matrix_free/point_evaluation_05.cc
+++ b/tests/matrix_free/point_evaluation_05.cc
@@ -130,7 +130,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_06.cc b/tests/matrix_free/point_evaluation_06.cc
index d37c868e66..6185b564bc 100644
--- a/tests/matrix_free/point_evaluation_06.cc
+++ b/tests/matrix_free/point_evaluation_06.cc
@@ -131,7 +131,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_07.cc b/tests/matrix_free/point_evaluation_07.cc
index 795d46ace2..a38a0056ae 100644
--- a/tests/matrix_free/point_evaluation_07.cc
+++ b/tests/matrix_free/point_evaluation_07.cc
@@ -145,7 +145,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_08.cc b/tests/matrix_free/point_evaluation_08.cc
index b4457c68d2..18fd245266 100644
--- a/tests/matrix_free/point_evaluation_08.cc
+++ b/tests/matrix_free/point_evaluation_08.cc
@@ -172,7 +172,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
 
       evaluator_scalar.integrate(solution_values,
@@ -180,7 +180,7 @@ test(const unsigned int degree)
                                    EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_09.cc b/tests/matrix_free/point_evaluation_09.cc
index ab2c3fb09e..85bd88a2c3 100644
--- a/tests/matrix_free/point_evaluation_09.cc
+++ b/tests/matrix_free/point_evaluation_09.cc
@@ -146,7 +146,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_10.cc b/tests/matrix_free/point_evaluation_10.cc
index f25138c165..6137f300de 100644
--- a/tests/matrix_free/point_evaluation_10.cc
+++ b/tests/matrix_free/point_evaluation_10.cc
@@ -124,7 +124,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_11.cc b/tests/matrix_free/point_evaluation_11.cc
index e176925ce4..46fcf2e510 100644
--- a/tests/matrix_free/point_evaluation_11.cc
+++ b/tests/matrix_free/point_evaluation_11.cc
@@ -122,7 +122,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_13.cc b/tests/matrix_free/point_evaluation_13.cc
index e7842aaf95..bbac06a9ac 100644
--- a/tests/matrix_free/point_evaluation_13.cc
+++ b/tests/matrix_free/point_evaluation_13.cc
@@ -136,7 +136,7 @@ test()
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_14.cc b/tests/matrix_free/point_evaluation_14.cc
index b7cfe43077..874bbb2fa4 100644
--- a/tests/matrix_free/point_evaluation_14.cc
+++ b/tests/matrix_free/point_evaluation_14.cc
@@ -141,7 +141,7 @@ test(const unsigned int degree)
                           EvaluationFlags::values | EvaluationFlags::gradients);
 
       for (const auto i : solution_values)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_15.cc b/tests/matrix_free/point_evaluation_15.cc
index 310f403a24..2ea31d92b8 100644
--- a/tests/matrix_free/point_evaluation_15.cc
+++ b/tests/matrix_free/point_evaluation_15.cc
@@ -144,7 +144,7 @@ test()
                              EvaluationFlags::gradients);
 
       for (unsigned int i = 0; i < solution_values.size(); ++i)
-        deallog << solution_values[i] - solution_values2[i] << " ";
+        deallog << solution_values[i] - solution_values2[i] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/point_evaluation_16.cc b/tests/matrix_free/point_evaluation_16.cc
index 07f609d6b6..4c52943982 100644
--- a/tests/matrix_free/point_evaluation_16.cc
+++ b/tests/matrix_free/point_evaluation_16.cc
@@ -143,7 +143,7 @@ test(const unsigned int degree)
                              EvaluationFlags::gradients);
 
       for (unsigned int i = 0; i < solution_values.size(); ++i)
-        deallog << solution_values[i] - solution_values2[i] << " ";
+        deallog << solution_values[i] - solution_values2[i] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/matrix_free/read_cell_data_02.cc b/tests/matrix_free/read_cell_data_02.cc
index e281f25a61..b04d705246 100644
--- a/tests/matrix_free/read_cell_data_02.cc
+++ b/tests/matrix_free/read_cell_data_02.cc
@@ -130,7 +130,7 @@ private:
                 Assert(cell_data_m[lane] ==
                          data.get_cell_iterator(cell, lane)->id(),
                        ExcInternalError());
-                // deallog << "m" << cell_data_m[lane] << std::endl;
+                // deallog << 'm' << cell_data_m[lane] << std::endl;
 
                 const auto bids =
                   data.get_faces_by_cells_boundary_id(cell, face);
diff --git a/tests/matrix_free/shape_info_inverse.cc b/tests/matrix_free/shape_info_inverse.cc
index f416b283db..1f8606cb1c 100644
--- a/tests/matrix_free/shape_info_inverse.cc
+++ b/tests/matrix_free/shape_info_inverse.cc
@@ -41,8 +41,8 @@ test(const FiniteElement<dim> &fe,
 {
   internal::MatrixFreeFunctions::ShapeInfo<double> shape_info;
   shape_info.reinit(quad, fe, 0);
-  deallog << "Testing " << fe.get_name() << " with " << quadrature_name << "("
-          << quad.size() << ")" << std::endl;
+  deallog << "Testing " << fe.get_name() << " with " << quadrature_name << '('
+          << quad.size() << ')' << std::endl;
   deallog << "shape values: " << std::endl;
   const auto &univariate_shape_data = shape_info.get_shape_data(0, 0);
   for (unsigned int i = 0; i < univariate_shape_data.fe_degree + 1; ++i)
@@ -50,7 +50,7 @@ test(const FiniteElement<dim> &fe,
       for (unsigned int q = 0; q < quad.size(); ++q)
         deallog << std::setw(15)
                 << univariate_shape_data.shape_values[i * quad.size() + q]
-                << " ";
+                << ' ';
       deallog << std::endl;
     }
   deallog << "inverse shape values: " << std::endl;
@@ -60,7 +60,7 @@ test(const FiniteElement<dim> &fe,
         deallog
           << std::setw(15)
           << univariate_shape_data.inverse_shape_values[i * quad.size() + q]
-          << " ";
+          << ' ';
       deallog << std::endl;
     }
   deallog << "inverse shapes' * shapes: " << std::endl;
@@ -73,7 +73,7 @@ test(const FiniteElement<dim> &fe,
             sum +=
               univariate_shape_data.inverse_shape_values[k * quad.size() + i] *
               univariate_shape_data.shape_values[k * quad.size() + j];
-          deallog << std::setw(15) << sum << " ";
+          deallog << std::setw(15) << sum << ' ';
         }
       deallog << std::endl;
     }
@@ -87,7 +87,7 @@ test(const FiniteElement<dim> &fe,
             sum +=
               univariate_shape_data.inverse_shape_values[i * quad.size() + k] *
               univariate_shape_data.shape_values[j * quad.size() + k];
-          deallog << std::setw(15) << sum << " ";
+          deallog << std::setw(15) << sum << ' ';
         }
       deallog << std::endl;
     }
diff --git a/tests/matrix_free/tensor_product_evaluate_01.cc b/tests/matrix_free/tensor_product_evaluate_01.cc
index 8e251844f3..aa63b00f09 100644
--- a/tests/matrix_free/tensor_product_evaluate_01.cc
+++ b/tests/matrix_free/tensor_product_evaluate_01.cc
@@ -80,7 +80,7 @@ test(const unsigned int degree)
 
   if (degree == 1)
     {
-      deallog << "Evaluate d-linear shortcut in " << dim << "d" << std::endl;
+      deallog << "Evaluate d-linear shortcut in " << dim << 'd' << std::endl;
       for (const auto &p : evaluation_points)
         {
           const auto val = internal::evaluate_tensor_product_value_and_gradient(
diff --git a/tests/matrix_free/tensor_product_evaluate_02.cc b/tests/matrix_free/tensor_product_evaluate_02.cc
index 34effebf09..0e40813fa3 100644
--- a/tests/matrix_free/tensor_product_evaluate_02.cc
+++ b/tests/matrix_free/tensor_product_evaluate_02.cc
@@ -76,7 +76,7 @@ test(const unsigned int degree)
 
   if (degree == 1)
     {
-      deallog << "Evaluate d-linear shortcut in " << dim << "d" << std::endl;
+      deallog << "Evaluate d-linear shortcut in " << dim << 'd' << std::endl;
       for (const auto &p : evaluation_points)
         {
           const auto val = internal::evaluate_tensor_product_value_and_gradient(
diff --git a/tests/matrix_free/tensor_product_evaluate_03.cc b/tests/matrix_free/tensor_product_evaluate_03.cc
index 908cc45bd7..840e6aaae7 100644
--- a/tests/matrix_free/tensor_product_evaluate_03.cc
+++ b/tests/matrix_free/tensor_product_evaluate_03.cc
@@ -92,7 +92,7 @@ test(const unsigned int degree)
 
   if (degree == 1)
     {
-      deallog << "Evaluate d-linear shortcut in " << dim << "d" << std::endl;
+      deallog << "Evaluate d-linear shortcut in " << dim << 'd' << std::endl;
       for (const auto &p : evaluation_points)
         {
           Point<dim, VectorizedArray<double>> p_vec;
diff --git a/tests/matrix_free/tensor_product_evaluate_04.cc b/tests/matrix_free/tensor_product_evaluate_04.cc
index 506f1d36c6..28b30aa58b 100644
--- a/tests/matrix_free/tensor_product_evaluate_04.cc
+++ b/tests/matrix_free/tensor_product_evaluate_04.cc
@@ -89,7 +89,7 @@ test(const unsigned int degree)
 
   if (degree == 1)
     {
-      deallog << "Evaluate d-linear shortcut in " << dim << "d" << std::endl;
+      deallog << "Evaluate d-linear shortcut in " << dim << 'd' << std::endl;
       for (const auto &p : evaluation_points)
         {
           Point<dim, VectorizedArray<double>> p_vec;
diff --git a/tests/meshworker/mesh_loop_04.cc b/tests/meshworker/mesh_loop_04.cc
index 473d5fb157..76dba2fcbe 100644
--- a/tests/meshworker/mesh_loop_04.cc
+++ b/tests/meshworker/mesh_loop_04.cc
@@ -119,7 +119,7 @@ test()
             boundary_worker,
             face_worker);
 
-  deallog << "Testing <" << dim << "," << spacedim << ">" << std::endl;
+  deallog << "Testing <" << dim << ',' << spacedim << '>' << std::endl;
 
   deallog << "Volume: " << std::get<0>(measures) << std::endl;
 
diff --git a/tests/meshworker/mesh_loop_05.cc b/tests/meshworker/mesh_loop_05.cc
index b938a21717..2e8d0d1d1e 100644
--- a/tests/meshworker/mesh_loop_05.cc
+++ b/tests/meshworker/mesh_loop_05.cc
@@ -135,7 +135,7 @@ test()
   std::get<2>(measures) =
     Utilities::MPI::sum(std::get<2>(measures), MPI_COMM_WORLD);
 
-  deallog << "Testing <" << dim << "," << spacedim << ">" << std::endl;
+  deallog << "Testing <" << dim << ',' << spacedim << '>' << std::endl;
 
   deallog << "Volume: " << std::get<0>(measures) << std::endl;
 
diff --git a/tests/meshworker/mesh_loop_06.cc b/tests/meshworker/mesh_loop_06.cc
index 20c8334560..288ae664dc 100644
--- a/tests/meshworker/mesh_loop_06.cc
+++ b/tests/meshworker/mesh_loop_06.cc
@@ -129,7 +129,7 @@ test(const types::material_id test_id)
             boundary_worker,
             face_worker);
 
-  deallog << "Testing <" << dim << "," << spacedim << ">" << std::endl;
+  deallog << "Testing <" << dim << ',' << spacedim << '>' << std::endl;
 
   deallog << "Volume: " << std::get<0>(measures) << std::endl;
 
diff --git a/tests/meshworker/scratch_data_01.cc b/tests/meshworker/scratch_data_01.cc
index fe6c20f6a2..ab65a572f7 100644
--- a/tests/meshworker/scratch_data_01.cc
+++ b/tests/meshworker/scratch_data_01.cc
@@ -120,7 +120,7 @@ test()
             boundary_worker,
             face_worker);
 
-  deallog << "Testing <" << dim << "," << spacedim << ">" << std::endl;
+  deallog << "Testing <" << dim << ',' << spacedim << '>' << std::endl;
 
   deallog << "Volume: " << std::get<0>(measures) << std::endl;
 
diff --git a/tests/metis/metis_02.cc b/tests/metis/metis_02.cc
index 533cbbd591..474f08dd03 100644
--- a/tests/metis/metis_02.cc
+++ b/tests/metis/metis_02.cc
@@ -42,7 +42,7 @@ template <int dim>
 void
 test()
 {
-  deallog << dim << "D" << std::endl;
+  deallog << dim << 'D' << std::endl;
 
   Triangulation<dim> triangulation;
   GridGenerator::hyper_cube(triangulation);
diff --git a/tests/metis/metis_04.cc b/tests/metis/metis_04.cc
index c48d4f7580..789866b4eb 100644
--- a/tests/metis/metis_04.cc
+++ b/tests/metis/metis_04.cc
@@ -59,7 +59,7 @@ test()
           triangulation.begin_active();
         for (; cell != triangulation.end(); ++cell)
           {
-            deallog << cell->subdomain_id() << " ";
+            deallog << cell->subdomain_id() << ' ';
           }
         deallog << std::endl;
       }
diff --git a/tests/mpi/active_cell_index_01.cc b/tests/mpi/active_cell_index_01.cc
index 090b9b0155..3341fa4595 100644
--- a/tests/mpi/active_cell_index_01.cc
+++ b/tests/mpi/active_cell_index_01.cc
@@ -61,7 +61,7 @@ check()
   check(tria);
 
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
-    deallog << "OK for " << dim << "d" << std::endl;
+    deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 
diff --git a/tests/mpi/allreduce_01.cc b/tests/mpi/allreduce_01.cc
index fcd5001af5..5d480bef0a 100644
--- a/tests/mpi/allreduce_01.cc
+++ b/tests/mpi/allreduce_01.cc
@@ -33,7 +33,7 @@ check(const std::function<std::vector<T>(const std::vector<T> &,
     fu);
 
   for (const auto r : result)
-    deallog << r << " ";
+    deallog << r << ' ';
   deallog << std::endl;
 
   for (unsigned int rank = 0;
@@ -47,7 +47,7 @@ check(const std::function<std::vector<T>(const std::vector<T> &,
         rank);
 
       for (const auto r : result)
-        deallog << r << " ";
+        deallog << r << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/mpi/blockwise_parallel_01.cc b/tests/mpi/blockwise_parallel_01.cc
index f2fb8078a2..9d34f161cc 100644
--- a/tests/mpi/blockwise_parallel_01.cc
+++ b/tests/mpi/blockwise_parallel_01.cc
@@ -71,7 +71,7 @@ test()
   }
 
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
-    deallog << "OK for " << dim << "d" << std::endl;
+    deallog << "OK for " << dim << 'd' << std::endl;
 }
 
 int
diff --git a/tests/mpi/broadcast_01.cc b/tests/mpi/broadcast_01.cc
index db92acf0de..d371c938fe 100644
--- a/tests/mpi/broadcast_01.cc
+++ b/tests/mpi/broadcast_01.cc
@@ -42,7 +42,7 @@ std::ostream &
 operator<<(std::ostream &os, const TestObject &test_object)
 {
   for (const auto &i : test_object.int_vector)
-    os << i << " ";
+    os << i << ' ';
 
   os << test_object.string;
 
@@ -64,7 +64,7 @@ check(const std::vector<int> &int_vector, const std::string &string)
 
   const auto result = Utilities::MPI::broadcast(MPI_COMM_WORLD, test_object);
 
-  deallog << result << " ";
+  deallog << result << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/mpi/communicate_moved_vertices_03.cc b/tests/mpi/communicate_moved_vertices_03.cc
index 5e1fe3feec..2691ce87c2 100644
--- a/tests/mpi/communicate_moved_vertices_03.cc
+++ b/tests/mpi/communicate_moved_vertices_03.cc
@@ -28,7 +28,7 @@ template <int dim>
 void
 test()
 {
-  deallog << "Testing " << Utilities::int_to_string(dim, 1) << "D" << std::endl;
+  deallog << "Testing " << Utilities::int_to_string(dim, 1) << 'D' << std::endl;
 
   parallel::distributed::Triangulation<dim> triangulation(MPI_COMM_WORLD);
   GridGenerator::hyper_cube(triangulation, -1., 1., true);
diff --git a/tests/mpi/communicator_duplicated.cc b/tests/mpi/communicator_duplicated.cc
index e86c069da7..32fe640a86 100644
--- a/tests/mpi/communicator_duplicated.cc
+++ b/tests/mpi/communicator_duplicated.cc
@@ -57,7 +57,7 @@ test(const MPI_Comm comm)
       MPI_Recv(&value[1], 1, MPI_UNSIGNED, src, tag, comm2, MPI_STATUS_IGNORE);
       MPI_Recv(&value[0], 1, MPI_UNSIGNED, src, tag, comm, MPI_STATUS_IGNORE);
 
-      deallog << value[0] << " " << value[1] << " " << value[2] << std::endl;
+      deallog << value[0] << ' ' << value[1] << ' ' << value[2] << std::endl;
     }
 
   Utilities::MPI::free_communicator(comm2);
diff --git a/tests/mpi/communicator_validity.cc b/tests/mpi/communicator_validity.cc
index 05f1717a57..4d0737358c 100644
--- a/tests/mpi/communicator_validity.cc
+++ b/tests/mpi/communicator_validity.cc
@@ -55,7 +55,7 @@ do_test(MPI_Comm communicator)
   typename VectorMemory<VectorType>::Pointer v3(memory);
   *v3 = v1;
 
-  deallog << v1.l2_norm() << " " << v3->l2_norm() << std::endl;
+  deallog << v1.l2_norm() << ' ' << v3->l2_norm() << std::endl;
 }
 
 
diff --git a/tests/mpi/compute_index_owner_01.cc b/tests/mpi/compute_index_owner_01.cc
index 9af835276c..b139350772 100644
--- a/tests/mpi/compute_index_owner_01.cc
+++ b/tests/mpi/compute_index_owner_01.cc
@@ -68,7 +68,7 @@ test()
 
     deallog << "owning_ranks_of_ghosts:" << std::endl;
     for (auto i : owning_ranks_of_ghosts)
-      deallog << i << " ";
+      deallog << i << ' ';
     deallog << std::endl;
 
     deallog << "requesters:" << std::endl;
diff --git a/tests/mpi/create_mpi_datatype_01.cc b/tests/mpi/create_mpi_datatype_01.cc
index 57c9340d1f..40db05eee5 100644
--- a/tests/mpi/create_mpi_datatype_01.cc
+++ b/tests/mpi/create_mpi_datatype_01.cc
@@ -31,7 +31,7 @@ test_data_type(const std::uint64_t n_bytes)
 {
   const auto bigtype = Utilities::MPI::create_mpi_data_type_n_bytes(n_bytes);
 
-  deallog << "checking size " << n_bytes << ":";
+  deallog << "checking size " << n_bytes << ':';
 
   int size32;
   int ierr = MPI_Type_size(*bigtype, &size32);
diff --git a/tests/mpi/distort_random_01.cc b/tests/mpi/distort_random_01.cc
index cadddd2d25..f8719ca5fd 100644
--- a/tests/mpi/distort_random_01.cc
+++ b/tests/mpi/distort_random_01.cc
@@ -59,7 +59,7 @@ test1(const bool keep_boundary)
          i < Utilities::MPI::n_mpi_processes(MPI_COMM_WORLD);
          ++i)
       {
-        deallog << "Process " << i << ":" << std::endl;
+        deallog << "Process " << i << ':' << std::endl;
         cat_file((filename + "-" + Utilities::int_to_string(i, 2)).c_str());
       }
 
diff --git a/tests/mpi/distort_random_02.cc b/tests/mpi/distort_random_02.cc
index e58f6f6de8..eb10f140e0 100644
--- a/tests/mpi/distort_random_02.cc
+++ b/tests/mpi/distort_random_02.cc
@@ -74,7 +74,7 @@ test1(const bool keep_boundary)
          i < Utilities::MPI::n_mpi_processes(MPI_COMM_WORLD);
          ++i)
       {
-        deallog << "Process " << i << ":" << std::endl;
+        deallog << "Process " << i << ':' << std::endl;
         cat_file((filename + "-" + Utilities::int_to_string(i, 2)).c_str());
       }
 
diff --git a/tests/mpi/distribute_sp_02.cc b/tests/mpi/distribute_sp_02.cc
index be76ca4e55..232c6ace70 100644
--- a/tests/mpi/distribute_sp_02.cc
+++ b/tests/mpi/distribute_sp_02.cc
@@ -60,9 +60,9 @@ test_mpi()
 
   if (myid == 0)
     {
-      deallog << "blocks: " << csp.n_block_rows() << "x" << csp.n_block_cols()
+      deallog << "blocks: " << csp.n_block_rows() << 'x' << csp.n_block_cols()
               << std::endl;
-      deallog << "size: " << csp.n_rows() << "x" << csp.n_cols() << std::endl;
+      deallog << "size: " << csp.n_rows() << 'x' << csp.n_cols() << std::endl;
     }
 
   SparsityTools::distribute_sparsity_pattern(csp,
@@ -118,9 +118,9 @@ test_mpi()
 
   if (myid == 0)
     {
-      deallog << "blocks: " << csp.n_block_rows() << "x" << csp.n_block_cols()
+      deallog << "blocks: " << csp.n_block_rows() << 'x' << csp.n_block_cols()
               << std::endl;
-      deallog << "size: " << csp.n_rows() << "x" << csp.n_cols() << std::endl;
+      deallog << "size: " << csp.n_rows() << 'x' << csp.n_cols() << std::endl;
     }
 
   // checking...
diff --git a/tests/mpi/extract_locally_active_level_dofs.cc b/tests/mpi/extract_locally_active_level_dofs.cc
index 54b8ae33f2..07b07ca8f5 100644
--- a/tests/mpi/extract_locally_active_level_dofs.cc
+++ b/tests/mpi/extract_locally_active_level_dofs.cc
@@ -69,7 +69,7 @@ test()
 
           for (unsigned int i = 0; i < locally_level_active.size(); ++i)
             if (locally_level_active.is_element(i))
-              deallog << i << " ";
+              deallog << i << ' ';
           deallog << "OK" << std::endl;
         }
     }
diff --git a/tests/mpi/ghost_01.cc b/tests/mpi/ghost_01.cc
index 78e70f2217..dca8a170be 100644
--- a/tests/mpi/ghost_01.cc
+++ b/tests/mpi/ghost_01.cc
@@ -61,9 +61,9 @@ test()
   // check local values
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
     {
-      deallog << myid * 2 << ":" << get_real_assert_zero_imag(v(myid * 2))
+      deallog << myid * 2 << ':' << get_real_assert_zero_imag(v(myid * 2))
               << std::endl;
-      deallog << myid * 2 + 1 << ":"
+      deallog << myid * 2 + 1 << ':'
               << get_real_assert_zero_imag(v(myid * 2 + 1)) << std::endl;
     }
 
diff --git a/tests/mpi/ghost_02.cc b/tests/mpi/ghost_02.cc
index 5e4b23b307..758bcb796d 100644
--- a/tests/mpi/ghost_02.cc
+++ b/tests/mpi/ghost_02.cc
@@ -69,9 +69,9 @@ test()
   // check local values
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
     {
-      deallog << myid * 2 << ":" << get_real_assert_zero_imag(v(myid * 2))
+      deallog << myid * 2 << ':' << get_real_assert_zero_imag(v(myid * 2))
               << std::endl;
-      deallog << myid * 2 + 1 << ":"
+      deallog << myid * 2 + 1 << ':'
               << get_real_assert_zero_imag(v(myid * 2 + 1)) << std::endl;
     }
 
diff --git a/tests/mpi/has_hanging_nodes.cc b/tests/mpi/has_hanging_nodes.cc
index 07ea9f3cc2..399e1520f9 100644
--- a/tests/mpi/has_hanging_nodes.cc
+++ b/tests/mpi/has_hanging_nodes.cc
@@ -134,7 +134,7 @@ test_int(const unsigned int n_global = 0, const unsigned int n_local = 0)
       tria_sequential.execute_coarsening_and_refinement();
     }
 
-  deallog << n_global << " " << n_local
+  deallog << n_global << ' ' << n_local
           << " distrib=" << tria_distrib.has_hanging_nodes()
           << "; shared=" << tria_sequential.has_hanging_nodes() << std::endl;
 }
diff --git a/tests/mpi/interpolate_to_different_mesh_01.cc b/tests/mpi/interpolate_to_different_mesh_01.cc
index d9a879044c..a3f95cacde 100644
--- a/tests/mpi/interpolate_to_different_mesh_01.cc
+++ b/tests/mpi/interpolate_to_different_mesh_01.cc
@@ -206,7 +206,7 @@ test()
       const unsigned int checksum  = tr.get_checksum();
       const unsigned int checksum2 = tr2.get_checksum();
       if (myid == 0)
-        deallog << "Checksum: " << checksum << " " << checksum2 << std::endl;
+        deallog << "Checksum: " << checksum << ' ' << checksum2 << std::endl;
     }
 }
 
diff --git a/tests/mpi/limit_p_level_difference_04.cc b/tests/mpi/limit_p_level_difference_04.cc
index b2143244a3..0f9eb1e882 100644
--- a/tests/mpi/limit_p_level_difference_04.cc
+++ b/tests/mpi/limit_p_level_difference_04.cc
@@ -103,7 +103,7 @@ test(const unsigned int max_difference)
   deallog << "active FE indices after adaptation:" << std::endl;
   for (const auto &cell :
        dofh.active_cell_iterators() | IteratorFilters::LocallyOwnedCell())
-    deallog << " " << cell->id().to_string() << " " << cell->active_fe_index()
+    deallog << ' ' << cell->id().to_string() << ' ' << cell->active_fe_index()
             << std::endl;
 
   deallog << "OK" << std::endl;
diff --git a/tests/mpi/mg_01.cc b/tests/mpi/mg_01.cc
index faa8d21fca..5c1948ad29 100644
--- a/tests/mpi/mg_01.cc
+++ b/tests/mpi/mg_01.cc
@@ -92,7 +92,7 @@ test()
                 if (cell->level_subdomain_id() != 4294967294)
                   deallog << cell->level_subdomain_id();
                 else
-                  deallog << "-";
+                  deallog << '-';
               deallog << std::endl;
             }
           deallog << std::endl;
diff --git a/tests/mpi/mg_02.cc b/tests/mpi/mg_02.cc
index 31696ec8cc..104b6ee9f1 100644
--- a/tests/mpi/mg_02.cc
+++ b/tests/mpi/mg_02.cc
@@ -71,7 +71,7 @@ test()
             if (cell->level_subdomain_id() != 4294967294)
               deallog << cell->level_subdomain_id();
             else
-              deallog << "-";
+              deallog << '-';
           }
         deallog << std::endl;
       }
@@ -104,7 +104,7 @@ test()
     deallog << "locally_owned_mg_dofs_per_processor:" << std::endl;
     for (unsigned int lvl = 0; lvl < tr.n_global_levels(); ++lvl)
       {
-        deallog << "level " << lvl << ":" << std::endl;
+        deallog << "level " << lvl << ':' << std::endl;
 
         const std::vector<IndexSet> vec =
           Utilities::MPI::all_gather(MPI_COMM_WORLD,
diff --git a/tests/mpi/mg_03.cc b/tests/mpi/mg_03.cc
index 9b8ab44f1f..1b19a54c10 100644
--- a/tests/mpi/mg_03.cc
+++ b/tests/mpi/mg_03.cc
@@ -117,7 +117,7 @@ test()
               if (dofs[i] == numbers::invalid_dof_index)
                 deallog << "- ";
               else
-                deallog << dofs[i] << " ";
+                deallog << dofs[i] << ' ';
             deallog << " | ";
           }
         deallog << std::endl;
diff --git a/tests/mpi/mg_04.cc b/tests/mpi/mg_04.cc
index e3b570371f..27ba5c709b 100644
--- a/tests/mpi/mg_04.cc
+++ b/tests/mpi/mg_04.cc
@@ -107,7 +107,7 @@ test()
               if (dofs[i] == numbers::invalid_dof_index)
                 deallog << "- ";
               else
-                deallog << dofs[i] << " ";
+                deallog << dofs[i] << ' ';
             deallog << " | ";
           }
         deallog << std::endl;
diff --git a/tests/mpi/mg_ghost_dofs_periodic_01.cc b/tests/mpi/mg_ghost_dofs_periodic_01.cc
index c4c769a631..7c37dcc712 100644
--- a/tests/mpi/mg_ghost_dofs_periodic_01.cc
+++ b/tests/mpi/mg_ghost_dofs_periodic_01.cc
@@ -93,7 +93,7 @@ test()
                     << cell->level_subdomain_id() << ": ";
             cell->get_mg_dof_indices(dof_indices);
             for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-              deallog << dof_indices[i] << " ";
+              deallog << dof_indices[i] << ' ';
             deallog << std::endl;
           }
     }
diff --git a/tests/mpi/mg_ghost_dofs_periodic_02.cc b/tests/mpi/mg_ghost_dofs_periodic_02.cc
index e974de1e06..780df9cf03 100644
--- a/tests/mpi/mg_ghost_dofs_periodic_02.cc
+++ b/tests/mpi/mg_ghost_dofs_periodic_02.cc
@@ -74,7 +74,7 @@ test()
                     << cell->level_subdomain_id() << ": ";
             cell->get_mg_dof_indices(dof_indices);
             for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-              deallog << dof_indices[i] << " ";
+              deallog << dof_indices[i] << ' ';
             deallog << std::endl;
           }
     }
diff --git a/tests/mpi/mg_ghost_dofs_periodic_03.cc b/tests/mpi/mg_ghost_dofs_periodic_03.cc
index dabc4a0fd0..e34b100781 100644
--- a/tests/mpi/mg_ghost_dofs_periodic_03.cc
+++ b/tests/mpi/mg_ghost_dofs_periodic_03.cc
@@ -86,7 +86,7 @@ test()
                         << ", owned by " << cell->level_subdomain_id() << ": ";
                 cell->get_mg_dof_indices(dof_indices);
                 for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-                  deallog << dof_indices[i] << " ";
+                  deallog << dof_indices[i] << ' ';
                 deallog << std::endl;
               }
         }
diff --git a/tests/mpi/mg_ghost_dofs_periodic_04.cc b/tests/mpi/mg_ghost_dofs_periodic_04.cc
index c443ee7cdb..653edbf76b 100644
--- a/tests/mpi/mg_ghost_dofs_periodic_04.cc
+++ b/tests/mpi/mg_ghost_dofs_periodic_04.cc
@@ -101,7 +101,7 @@ test()
                     << cell->level_subdomain_id() << ": ";
             cell->get_mg_dof_indices(dof_indices);
             for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-              deallog << dof_indices[i] << " ";
+              deallog << dof_indices[i] << ' ';
             deallog << std::endl;
           }
     }
diff --git a/tests/mpi/mg_ghost_dofs_periodic_05.cc b/tests/mpi/mg_ghost_dofs_periodic_05.cc
index 51ed913416..e6c774b30b 100644
--- a/tests/mpi/mg_ghost_dofs_periodic_05.cc
+++ b/tests/mpi/mg_ghost_dofs_periodic_05.cc
@@ -75,7 +75,7 @@ test()
   dof_handler.distribute_mg_dofs();
   deallog << "Number of DoFs per level: ";
   for (unsigned int level = 0; level < tria.n_global_levels(); ++level)
-    deallog << dof_handler.n_dofs(level) << " ";
+    deallog << dof_handler.n_dofs(level) << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/mpi/mg_ghost_dofs_periodic_06.cc b/tests/mpi/mg_ghost_dofs_periodic_06.cc
index 84020fa76b..3a62ce3130 100644
--- a/tests/mpi/mg_ghost_dofs_periodic_06.cc
+++ b/tests/mpi/mg_ghost_dofs_periodic_06.cc
@@ -79,7 +79,7 @@ test()
   for (typename Triangulation<dim>::cell_iterator cell = tria.begin();
        cell != tria.end();
        ++cell)
-    deallog << cell->id().to_string() << " " << cell->level_subdomain_id()
+    deallog << cell->id().to_string() << ' ' << cell->level_subdomain_id()
             << std::endl;
 
   if (0)
diff --git a/tests/mpi/mg_ghost_dofs_periodic_07.cc b/tests/mpi/mg_ghost_dofs_periodic_07.cc
index 9191e62396..b24735be27 100644
--- a/tests/mpi/mg_ghost_dofs_periodic_07.cc
+++ b/tests/mpi/mg_ghost_dofs_periodic_07.cc
@@ -70,7 +70,7 @@ test()
   for (typename Triangulation<dim>::cell_iterator cell = tria.begin();
        cell != tria.end();
        ++cell)
-    deallog << cell->id().to_string() << " " << cell->level_subdomain_id()
+    deallog << cell->id().to_string() << ' ' << cell->level_subdomain_id()
             << std::endl;
 
   FE_DGQ<dim>     fe1(1);
diff --git a/tests/mpi/mg_ghost_layer_periodic.cc b/tests/mpi/mg_ghost_layer_periodic.cc
index d5f1c4d39f..ae59723a75 100644
--- a/tests/mpi/mg_ghost_layer_periodic.cc
+++ b/tests/mpi/mg_ghost_layer_periodic.cc
@@ -63,15 +63,15 @@ test()
       for (const auto &cell : tria.cell_iterators())
         if (cell->level_subdomain_id() == tria.locally_owned_subdomain())
           {
-            deallog << Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) << " "
+            deallog << Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) << ' '
                     << cell->id() << " neighbor subdomain ids: ";
             for (unsigned int f : GeometryInfo<dim>::face_indices())
               {
-                deallog << cell->neighbor_or_periodic_neighbor(f)->id() << " ";
+                deallog << cell->neighbor_or_periodic_neighbor(f)->id() << ' ';
                 if (cell->is_active())
                   deallog
                     << cell->neighbor_or_periodic_neighbor(f)->subdomain_id()
-                    << " ";
+                    << ' ';
                 deallog << cell->neighbor_or_periodic_neighbor(f)
                              ->level_subdomain_id()
                         << "  ";
diff --git a/tests/mpi/p4est_2d_coarse_01.cc b/tests/mpi/p4est_2d_coarse_01.cc
index 9b56305c01..d2b6f8bc7b 100644
--- a/tests/mpi/p4est_2d_coarse_01.cc
+++ b/tests/mpi/p4est_2d_coarse_01.cc
@@ -65,7 +65,7 @@ test()
 
       //      GridTools::get_subdomain_association(tr, cell_subd);
       //       for (unsigned int i=0;i<tr.n_active_cells();++i)
-      //  deallog << cell_subd[i] << " ";
+      //  deallog << cell_subd[i] << ' ';
       //       deallog << std::endl;
 
       if (myid == 0)
diff --git a/tests/mpi/p4est_2d_dofhandler_01.cc b/tests/mpi/p4est_2d_dofhandler_01.cc
index 9a00003822..0ea9275a7b 100644
--- a/tests/mpi/p4est_2d_dofhandler_01.cc
+++ b/tests/mpi/p4est_2d_dofhandler_01.cc
@@ -79,7 +79,7 @@ test()
           cell->get_dof_indices(local_dof_indices);
 
           for (unsigned int i = 0; i < dofs_per_cell; ++i)
-            deallog << local_dof_indices[i] << " ";
+            deallog << local_dof_indices[i] << ' ';
 
           deallog << std::endl;
         }
diff --git a/tests/mpi/p4est_2d_ghost_01.cc b/tests/mpi/p4est_2d_ghost_01.cc
index 3597c264a8..500b0552db 100644
--- a/tests/mpi/p4est_2d_ghost_01.cc
+++ b/tests/mpi/p4est_2d_ghost_01.cc
@@ -54,7 +54,7 @@ test()
 
           GridTools::get_subdomain_association(tr, cell_subd);
           for (unsigned int i = 0; i < tr.n_active_cells(); ++i)
-            deallog << cell_subd[i] << " ";
+            deallog << cell_subd[i] << ' ';
           deallog << std::endl;
         }
 
diff --git a/tests/mpi/p4est_2d_ghost_02.cc b/tests/mpi/p4est_2d_ghost_02.cc
index 7a4d1c0899..d6420175af 100644
--- a/tests/mpi/p4est_2d_ghost_02.cc
+++ b/tests/mpi/p4est_2d_ghost_02.cc
@@ -60,7 +60,7 @@ test()
 
               GridTools::get_subdomain_association(tr, cell_subd);
               for (unsigned int i = 0; i < tr.n_active_cells(); ++i)
-                deallog << cell_subd[i] << " ";
+                deallog << cell_subd[i] << ' ';
               deallog << std::endl;
             }
 
diff --git a/tests/mpi/p4est_2d_refine_01.cc b/tests/mpi/p4est_2d_refine_01.cc
index a4407515f4..bea3487e74 100644
--- a/tests/mpi/p4est_2d_refine_01.cc
+++ b/tests/mpi/p4est_2d_refine_01.cc
@@ -54,7 +54,7 @@ test()
       if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
         {
           for (unsigned int i = 0; i < tr.n_active_cells(); ++i)
-            deallog << cell_subd[i] << " ";
+            deallog << cell_subd[i] << ' ';
           deallog << std::endl;
         }
 
diff --git a/tests/mpi/p4est_2d_renumber_01.cc b/tests/mpi/p4est_2d_renumber_01.cc
index b601afe084..0044352c1c 100644
--- a/tests/mpi/p4est_2d_renumber_01.cc
+++ b/tests/mpi/p4est_2d_renumber_01.cc
@@ -96,7 +96,7 @@ test()
                   cell->get_dof_indices(local_dof_indices);
                   for (unsigned int i = 0; i < cell->get_fe().dofs_per_cell;
                        ++i)
-                    deallog << local_dof_indices[i] << " ";
+                    deallog << local_dof_indices[i] << ' ';
                   deallog << std::endl;
                 }
         }
diff --git a/tests/mpi/p4est_2d_renumber_02.cc b/tests/mpi/p4est_2d_renumber_02.cc
index 828a602d5e..017e6cfc51 100644
--- a/tests/mpi/p4est_2d_renumber_02.cc
+++ b/tests/mpi/p4est_2d_renumber_02.cc
@@ -107,7 +107,7 @@ test()
                 local_dof_indices.resize(cell->get_fe().dofs_per_cell);
                 cell->get_dof_indices(local_dof_indices);
                 for (unsigned int i = 0; i < cell->get_fe().dofs_per_cell; ++i)
-                  deallog << local_dof_indices[i] << " ";
+                  deallog << local_dof_indices[i] << ' ';
                 deallog << std::endl;
               }
       }
diff --git a/tests/mpi/p4est_3d_ghost_01.cc b/tests/mpi/p4est_3d_ghost_01.cc
index a70c41554f..bf3669d1c6 100644
--- a/tests/mpi/p4est_3d_ghost_01.cc
+++ b/tests/mpi/p4est_3d_ghost_01.cc
@@ -65,7 +65,7 @@ test()
 
           GridTools::get_subdomain_association(tr, cell_subd);
           for (unsigned int i = 0; i < tr.n_active_cells(); ++i)
-            deallog << cell_subd[i] << " ";
+            deallog << cell_subd[i] << ' ';
           deallog << std::endl;
         }
 
@@ -120,7 +120,7 @@ main(int argc, char *argv[])
 
   unsigned int myid = Utilities::MPI::this_mpi_process(MPI_COMM_WORLD);
 
-  std::cout << myid << ":" << getpid() << std::endl;
+  std::cout << myid << ':' << getpid() << std::endl;
   // system("sleep 20");
 
 
diff --git a/tests/mpi/p4est_save_03.cc b/tests/mpi/p4est_save_03.cc
index 4583955c4c..976554ba26 100644
--- a/tests/mpi/p4est_save_03.cc
+++ b/tests/mpi/p4est_save_03.cc
@@ -166,7 +166,7 @@ test()
         deallog << "cells(0) = " << tr.n_active_cells() << std::endl;
       }
     deallog << "Checksum: " << tr.get_checksum() << std::endl;
-    deallog << "sum: " << norm << " " << norm2 << std::endl;
+    deallog << "sum: " << norm << ' ' << norm2 << std::endl;
   }
 
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
diff --git a/tests/mpi/p_adaptivity_fixed_number.cc b/tests/mpi/p_adaptivity_fixed_number.cc
index ec451d6697..ff001e5eca 100644
--- a/tests/mpi/p_adaptivity_fixed_number.cc
+++ b/tests/mpi/p_adaptivity_fixed_number.cc
@@ -50,8 +50,8 @@ validate(const DoFHandler<dim> &dh)
         const unsigned int coarse_cellid =
           std::stoul(cellid.substr(0, cellid.find("_")));
 
-        deallog << " (" << coarse_cellid << "," << cell->future_fe_index()
-                << ")";
+        deallog << " (" << coarse_cellid << ',' << cell->future_fe_index()
+                << ')';
       }
   deallog << std::endl;
 }
diff --git a/tests/mpi/parallel_block_vector_10.cc b/tests/mpi/parallel_block_vector_10.cc
index 029456e072..d5519bcc00 100644
--- a/tests/mpi/parallel_block_vector_10.cc
+++ b/tests/mpi/parallel_block_vector_10.cc
@@ -149,7 +149,7 @@ test(const unsigned int n_blocks = 5)
 
   const double diff_norm  = std::abs(res - res2);
   const double diff_norm2 = std::abs(res - res3);
-  deallog << "Norm of difference: " << diff_norm << " " << diff_norm2
+  deallog << "Norm of difference: " << diff_norm << ' ' << diff_norm2
           << std::endl;
 }
 
diff --git a/tests/mpi/parallel_partitioner_03.cc b/tests/mpi/parallel_partitioner_03.cc
index 66c3114e7d..70fa53892d 100644
--- a/tests/mpi/parallel_partitioner_03.cc
+++ b/tests/mpi/parallel_partitioner_03.cc
@@ -76,18 +76,18 @@ test()
     file << "**** proc " << myid << std::endl;
     file << "ghost targets: ";
     for (unsigned int i = 0; i < v.ghost_targets().size(); ++i)
-      file << "[" << v.ghost_targets()[i].first << "/"
+      file << '[' << v.ghost_targets()[i].first << '/'
            << v.ghost_targets()[i].second << "] ";
     file << std::endl;
     file << "import targets: ";
     for (unsigned int i = 0; i < v.import_targets().size(); ++i)
-      file << "[" << v.import_targets()[i].first << "/"
+      file << '[' << v.import_targets()[i].first << '/'
            << v.import_targets()[i].second << "] ";
     file << std::endl;
     file << "import indices:" << std::endl;
     for (unsigned int i = 0; i < v.import_indices().size(); ++i)
-      file << "[" << v.import_indices()[i].first << "/"
-           << v.import_indices()[i].second << ")" << std::endl;
+      file << '[' << v.import_indices()[i].first << '/'
+           << v.import_indices()[i].second << ')' << std::endl;
     file << "****" << std::endl;
   }
 
diff --git a/tests/mpi/parallel_partitioner_03b.cc b/tests/mpi/parallel_partitioner_03b.cc
index 80974ec835..41bab4a211 100644
--- a/tests/mpi/parallel_partitioner_03b.cc
+++ b/tests/mpi/parallel_partitioner_03b.cc
@@ -111,18 +111,18 @@ test()
     local_relevant.print(file);
     file << "ghost targets: ";
     for (unsigned int i = 0; i < v.ghost_targets().size(); ++i)
-      file << "[" << v.ghost_targets()[i].first << "/"
+      file << '[' << v.ghost_targets()[i].first << '/'
            << v.ghost_targets()[i].second << "] ";
     file << std::endl;
     file << "import targets: ";
     for (unsigned int i = 0; i < v.import_targets().size(); ++i)
-      file << "[" << v.import_targets()[i].first << "/"
+      file << '[' << v.import_targets()[i].first << '/'
            << v.import_targets()[i].second << "] ";
     file << std::endl;
     file << "import indices:" << std::endl;
     for (unsigned int i = 0; i < v.import_indices().size(); ++i)
-      file << "[" << v.import_indices()[i].first << "/"
-           << v.import_indices()[i].second << ")" << std::endl;
+      file << '[' << v.import_indices()[i].first << '/'
+           << v.import_indices()[i].second << ')' << std::endl;
     file << "****" << std::endl;
   }
 
diff --git a/tests/mpi/parallel_partitioner_05.cc b/tests/mpi/parallel_partitioner_05.cc
index 81467b206b..9bc7b53aee 100644
--- a/tests/mpi/parallel_partitioner_05.cc
+++ b/tests/mpi/parallel_partitioner_05.cc
@@ -101,21 +101,21 @@ test()
   deallog << "Ghost subset in " << v.n_ghost_indices() << " indices: ";
   for (unsigned int i = 0; i < v.ghost_indices_within_larger_ghost_set().size();
        ++i)
-    deallog << "[" << v.ghost_indices_within_larger_ghost_set()[i].first << ", "
+    deallog << '[' << v.ghost_indices_within_larger_ghost_set()[i].first << ", "
             << v.ghost_indices_within_larger_ghost_set()[i].second << ") ";
   deallog << std::endl;
 
   deallog << "Ghost subset in " << w.n_ghost_indices() << " indices: ";
   for (unsigned int i = 0; i < w.ghost_indices_within_larger_ghost_set().size();
        ++i)
-    deallog << "[" << w.ghost_indices_within_larger_ghost_set()[i].first << ", "
+    deallog << '[' << w.ghost_indices_within_larger_ghost_set()[i].first << ", "
             << w.ghost_indices_within_larger_ghost_set()[i].second << ") ";
   deallog << std::endl;
 
   deallog << "Ghost subset in " << x.n_ghost_indices() << " indices: ";
   for (unsigned int i = 0; i < x.ghost_indices_within_larger_ghost_set().size();
        ++i)
-    deallog << "[" << x.ghost_indices_within_larger_ghost_set()[i].first << ", "
+    deallog << '[' << x.ghost_indices_within_larger_ghost_set()[i].first << ", "
             << x.ghost_indices_within_larger_ghost_set()[i].second << ") ";
   deallog << std::endl;
 }
diff --git a/tests/mpi/parallel_partitioner_06.cc b/tests/mpi/parallel_partitioner_06.cc
index d9b536224d..4176feb175 100644
--- a/tests/mpi/parallel_partitioner_06.cc
+++ b/tests/mpi/parallel_partitioner_06.cc
@@ -108,7 +108,7 @@ test()
   v.export_to_ghosted_array_finish(make_array_view(ghosts), requests);
   deallog << "All ghosts: ";
   for (unsigned int i = 0; i < ghosts.size(); ++i)
-    deallog << ghosts[i] << " ";
+    deallog << ghosts[i] << ' ';
   deallog << std::endl;
 
   // send only the array in w
@@ -136,7 +136,7 @@ test()
   w.export_to_ghosted_array_finish(make_array_view(ghosts), requests);
   deallog << "Ghosts on reduced 1: ";
   for (unsigned int i = 0; i < ghosts.size(); ++i)
-    deallog << ghosts[i] << " ";
+    deallog << ghosts[i] << ' ';
   deallog << std::endl;
 
   std::fill(ghosts.begin(), ghosts.end(), 0);
@@ -150,13 +150,13 @@ test()
   x.export_to_ghosted_array_finish(make_array_view(ghosts), requests);
   deallog << "Ghosts on reduced 2: ";
   for (unsigned int i = 0; i < ghosts.size(); ++i)
-    deallog << ghosts[i] << " ";
+    deallog << ghosts[i] << ' ';
   deallog << std::endl;
 
   x.export_to_ghosted_array_finish(make_array_view(ghosts2), requests2);
   deallog << "Ghosts on reduced 2 without excess entries: ";
   for (unsigned int i = 0; i < ghosts2.size(); ++i)
-    deallog << ghosts2[i] << " ";
+    deallog << ghosts2[i] << ' ';
   deallog << std::endl;
 
   x.export_to_ghosted_array_start(3,
@@ -167,7 +167,7 @@ test()
   x.export_to_ghosted_array_finish(make_array_view(ghosts), requests);
   deallog << "Ghosts on reduced 2: ";
   for (unsigned int i = 0; i < ghosts.size(); ++i)
-    deallog << ghosts[i] << " ";
+    deallog << ghosts[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/mpi/parallel_partitioner_07.cc b/tests/mpi/parallel_partitioner_07.cc
index b6213c16e8..9f9049d72b 100644
--- a/tests/mpi/parallel_partitioner_07.cc
+++ b/tests/mpi/parallel_partitioner_07.cc
@@ -116,7 +116,7 @@ test()
   }
   deallog << "From all ghosts: ";
   for (unsigned int i = 0; i < locally_owned_array.size(); ++i)
-    deallog << locally_owned_array[i] << " ";
+    deallog << locally_owned_array[i] << ' ';
   deallog << std::endl;
 
   // send only the array in w
@@ -142,7 +142,7 @@ test()
   }
   deallog << "From reduced ghosts 1: ";
   for (unsigned int i = 0; i < locally_owned_array.size(); ++i)
-    deallog << locally_owned_array[i] << " ";
+    deallog << locally_owned_array[i] << ' ';
   deallog << std::endl;
 
   // send only the array in x
@@ -168,7 +168,7 @@ test()
   }
   deallog << "From reduced ghosts 2: ";
   for (unsigned int i = 0; i < locally_owned_array.size(); ++i)
-    deallog << locally_owned_array[i] << " ";
+    deallog << locally_owned_array[i] << ' ';
   deallog << std::endl;
 
   // now send a tight array from x and add into the existing entries
@@ -186,7 +186,7 @@ test()
     requests);
   deallog << "From tight reduced ghosts 2: ";
   for (unsigned int i = 0; i < locally_owned_array.size(); ++i)
-    deallog << locally_owned_array[i] << " ";
+    deallog << locally_owned_array[i] << ' ';
   deallog << std::endl;
 }
 
diff --git a/tests/mpi/parallel_partitioner_08.cc b/tests/mpi/parallel_partitioner_08.cc
index bad8064f93..30fc0422f7 100644
--- a/tests/mpi/parallel_partitioner_08.cc
+++ b/tests/mpi/parallel_partitioner_08.cc
@@ -110,10 +110,10 @@ test()
   auto print = [&]() {
     deallog << "owned:" << std::endl;
     for (auto el : owned)
-      deallog << el << " ";
+      deallog << el << ' ';
     deallog << std::endl << "ghost:" << std::endl;
     for (auto el : ghost)
-      deallog << el << " ";
+      deallog << el << ' ';
     deallog << std::endl;
   };
 
diff --git a/tests/mpi/parallel_partitioner_09.cc b/tests/mpi/parallel_partitioner_09.cc
index 4f127841a6..97c3f5ba20 100644
--- a/tests/mpi/parallel_partitioner_09.cc
+++ b/tests/mpi/parallel_partitioner_09.cc
@@ -39,14 +39,14 @@ main(int argc, char **argv)
 
   deallog << "ghost targets: ";
   for (const auto &p : part.ghost_targets())
-    deallog << "p" << p.first << " n_indices=" << p.second << "   ";
+    deallog << 'p' << p.first << " n_indices=" << p.second << "   ";
   deallog << std::endl;
   deallog << "import targets: ";
   for (const auto &p : part.import_targets())
-    deallog << "p" << p.first << " n_indices=" << p.second << "   ";
+    deallog << 'p' << p.first << " n_indices=" << p.second << "   ";
   deallog << std::endl;
   deallog << "import indices: ";
   for (const auto &p : part.import_indices())
-    deallog << "[" << p.first << " " << p.second << ") ";
+    deallog << '[' << p.first << ' ' << p.second << ") ";
   deallog << std::endl;
 }
diff --git a/tests/mpi/parallel_vector_01.cc b/tests/mpi/parallel_vector_01.cc
index 830963165c..a98439e4df 100644
--- a/tests/mpi/parallel_vector_01.cc
+++ b/tests/mpi/parallel_vector_01.cc
@@ -55,8 +55,8 @@ test()
 
   if (myid == 0)
     {
-      deallog << myid * 2 << ":" << v(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << v(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << v(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << v(myid * 2 + 1) << std::endl;
     }
 
   Assert(v(myid * 2) == myid * 4.0, ExcInternalError());
diff --git a/tests/mpi/parallel_vector_02.cc b/tests/mpi/parallel_vector_02.cc
index b17277a8a1..21d25114e9 100644
--- a/tests/mpi/parallel_vector_02.cc
+++ b/tests/mpi/parallel_vector_02.cc
@@ -65,8 +65,8 @@ test()
 
   if (myid == 0)
     {
-      deallog << myid * 2 << ":" << v(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << v(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << v(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << v(myid * 2 + 1) << std::endl;
     }
 
   // import ghosts onto all procs
diff --git a/tests/mpi/parallel_vector_03.cc b/tests/mpi/parallel_vector_03.cc
index b9917ca633..52e9aa4957 100644
--- a/tests/mpi/parallel_vector_03.cc
+++ b/tests/mpi/parallel_vector_03.cc
@@ -66,8 +66,8 @@ test()
 
   if (myid == 0)
     {
-      deallog << myid * 2 << ":" << v(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << v(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << v(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << v(myid * 2 + 1) << std::endl;
     }
 
   // import ghosts onto all procs
diff --git a/tests/mpi/parallel_vector_13.cc b/tests/mpi/parallel_vector_13.cc
index 23592d5911..0411138349 100644
--- a/tests/mpi/parallel_vector_13.cc
+++ b/tests/mpi/parallel_vector_13.cc
@@ -70,8 +70,8 @@ test()
 
   if (myid == 0)
     {
-      deallog << myid * 2 << ":" << v(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << v(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << v(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << v(myid * 2 + 1) << std::endl;
     }
 
   v(1) = -7;
@@ -79,8 +79,8 @@ test()
 
   if (myid == 0)
     {
-      deallog << myid * 2 << ":" << v(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << v(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << v(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << v(myid * 2 + 1) << std::endl;
     }
 
   // import ghosts onto all procs
diff --git a/tests/mpi/parallel_vector_16.cc b/tests/mpi/parallel_vector_16.cc
index 26a33f895d..ee1e7be428 100644
--- a/tests/mpi/parallel_vector_16.cc
+++ b/tests/mpi/parallel_vector_16.cc
@@ -57,7 +57,7 @@ test()
                                                MPI_COMM_WORLD);
 
   deallog << "Local range of proc 0: "
-          << v.get_partitioner()->local_range().first << " "
+          << v.get_partitioner()->local_range().first << ' '
           << v.get_partitioner()->local_range().second << std::endl;
 
   // set local values
diff --git a/tests/mpi/parallel_vector_17.cc b/tests/mpi/parallel_vector_17.cc
index 1db03bd204..b509fb85a9 100644
--- a/tests/mpi/parallel_vector_17.cc
+++ b/tests/mpi/parallel_vector_17.cc
@@ -63,43 +63,43 @@ test()
   v6.reinit(local_owned_b, newcomm);
 
   deallog << "local compatibility  v1-v2: "
-          << v1.partitioners_are_compatible(*v2.get_partitioner()) << " "
+          << v1.partitioners_are_compatible(*v2.get_partitioner()) << ' '
           << v2.partitioners_are_compatible(*v1.get_partitioner()) << std::endl;
   deallog << "global compatibility v1-v2: "
           << v1.partitioners_are_globally_compatible(*v2.get_partitioner())
-          << " "
+          << ' '
           << v2.partitioners_are_globally_compatible(*v1.get_partitioner())
           << std::endl;
   deallog << "local compatibility  v2-v3: "
-          << v2.partitioners_are_compatible(*v3.get_partitioner()) << " "
+          << v2.partitioners_are_compatible(*v3.get_partitioner()) << ' '
           << v3.partitioners_are_compatible(*v2.get_partitioner()) << std::endl;
   deallog << "global compatibility v2-v3: "
           << v2.partitioners_are_globally_compatible(*v3.get_partitioner())
-          << " "
+          << ' '
           << v3.partitioners_are_globally_compatible(*v2.get_partitioner())
           << std::endl;
   deallog << "local compatibility  v3-v4: "
-          << v4.partitioners_are_compatible(*v3.get_partitioner()) << " "
+          << v4.partitioners_are_compatible(*v3.get_partitioner()) << ' '
           << v3.partitioners_are_compatible(*v4.get_partitioner()) << std::endl;
   deallog << "global compatibility v3-v4: "
           << v4.partitioners_are_globally_compatible(*v3.get_partitioner())
-          << " "
+          << ' '
           << v3.partitioners_are_globally_compatible(*v4.get_partitioner())
           << std::endl;
   deallog << "local compatibility  v4-v5: "
-          << v4.partitioners_are_compatible(*v5.get_partitioner()) << " "
+          << v4.partitioners_are_compatible(*v5.get_partitioner()) << ' '
           << v5.partitioners_are_compatible(*v4.get_partitioner()) << std::endl;
   deallog << "global compatibility v4-v5: "
           << v4.partitioners_are_globally_compatible(*v5.get_partitioner())
-          << " "
+          << ' '
           << v5.partitioners_are_globally_compatible(*v4.get_partitioner())
           << std::endl;
   deallog << "local compatibility  v5-v6: "
-          << v6.partitioners_are_compatible(*v5.get_partitioner()) << " "
+          << v6.partitioners_are_compatible(*v5.get_partitioner()) << ' '
           << v5.partitioners_are_compatible(*v6.get_partitioner()) << std::endl;
   deallog << "global compatibility v5-v6: "
           << v6.partitioners_are_globally_compatible(*v5.get_partitioner())
-          << " "
+          << ' '
           << v5.partitioners_are_globally_compatible(*v6.get_partitioner())
           << std::endl;
 }
diff --git a/tests/mpi/parallel_vector_22.cc b/tests/mpi/parallel_vector_22.cc
index 975b739b06..d0ba3c159b 100644
--- a/tests/mpi/parallel_vector_22.cc
+++ b/tests/mpi/parallel_vector_22.cc
@@ -57,10 +57,9 @@ test()
   v *= 2.0;
 
   // check setup of vectors
-  deallog << myid << ":"
-          << "first owned entry: " << v(myid * 2) << std::endl;
-  deallog << myid << ":"
-          << "second owned entry: " << v(myid * 2 + 1) << std::endl;
+  deallog << myid << ':' << "first owned entry: " << v(myid * 2) << std::endl;
+  deallog << myid << ':' << "second owned entry: " << v(myid * 2 + 1)
+          << std::endl;
 
   // set ghost dof on owning processor and maximize
   if (myid)
@@ -71,8 +70,8 @@ test()
   v.update_ghost_values();
 
   // check
-  deallog << myid << ":"
-          << "ghost entry after max from owner: " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after max from owner: " << v(1)
+          << std::endl;
 
   // ghosts are set to zero
   v.zero_out_ghost_values();
@@ -82,8 +81,8 @@ test()
   v.update_ghost_values();
 
   // check
-  deallog << myid << ":"
-          << "ghost entry after min from zero: " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after min from zero: " << v(1)
+          << std::endl;
 
   // set ghost dof on non-owning processors and minimize
   v.zero_out_ghost_values();
@@ -93,8 +92,8 @@ test()
   v.update_ghost_values();
 
   // check
-  deallog << myid << ":"
-          << "ghost entry after min from : " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after min from : " << v(1)
+          << std::endl;
 
   // set vector to 1, zeros in ghosts except on owner where -1. is set
   v.zero_out_ghost_values();
@@ -108,8 +107,8 @@ test()
 
   // even if only one value is set (-1. on owner), the other values
   // contribute a "0" and maximization receives zero and returns it
-  deallog << myid << ":"
-          << "ghost entry after max and partly init: " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after max and partly init: " << v(1)
+          << std::endl;
 
   // however, if the ghost value is set on all processors, the
   // maximum is -1:
@@ -118,8 +117,8 @@ test()
   v(1) = -1.0;
   v.compress(VectorOperation::max);
   v.update_ghost_values();
-  deallog << myid << ":"
-          << "ghost entry after max and full init: " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after max and full init: " << v(1)
+          << std::endl;
 
   // what happens in case max is called two times and all values were smaller
   // than zero
@@ -127,11 +126,11 @@ test()
   v    = -1.0;
   v(1) = -1.0;
   v.compress(VectorOperation::max);
-  deallog << myid << ":"
-          << "ghost entry after first max: " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after first max: " << v(1)
+          << std::endl;
   v.compress(VectorOperation::max);
-  deallog << myid << ":"
-          << "ghost entry after second max: " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after second max: " << v(1)
+          << std::endl;
 
   if (myid == 0)
     deallog << "OK" << std::endl;
diff --git a/tests/mpi/parallel_vector_23.cc b/tests/mpi/parallel_vector_23.cc
index ae79e2112b..662c91c01e 100644
--- a/tests/mpi/parallel_vector_23.cc
+++ b/tests/mpi/parallel_vector_23.cc
@@ -61,8 +61,7 @@ test()
   v.import(read_write_vector, VectorOperation::max);
   v.update_ghost_values();
 
-  deallog << myid << ":"
-          << "ghost entry after max: " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after max: " << v(1) << std::endl;
 
   if (!myid)
     read_write_vector(1) = -1.0;
@@ -70,8 +69,7 @@ test()
   v.import(read_write_vector, VectorOperation::min);
   v.update_ghost_values();
 
-  deallog << myid << ":"
-          << "ghost entry after min: " << v(1) << std::endl;
+  deallog << myid << ':' << "ghost entry after min: " << v(1) << std::endl;
 
 
   if (myid == 0)
diff --git a/tests/mpi/periodicity_06.cc b/tests/mpi/periodicity_06.cc
index 2df0738896..c7e4582d67 100644
--- a/tests/mpi/periodicity_06.cc
+++ b/tests/mpi/periodicity_06.cc
@@ -210,9 +210,9 @@ test(const unsigned numRefinementLevels = 2)
   if (locally_relevant_dofs.is_element(i) && constraints.is_constrained(i))
     {
       deallog << "Coordinates:" << std::endl;
-      deallog << i << "@" << supportPoints[i] << std::endl;
+      deallog << i << '@' << supportPoints[i] << std::endl;
       for (auto c : *constraints.get_constraint_entries(i))
-        deallog << c.first << "@" << supportPoints[c.first] << std::endl;
+        deallog << c.first << '@' << supportPoints[c.first] << std::endl;
     }
 }
 
diff --git a/tests/mpi/simple_mpi_01.cc b/tests/mpi/simple_mpi_01.cc
index 29e3197e4c..f84b567104 100644
--- a/tests/mpi/simple_mpi_01.cc
+++ b/tests/mpi/simple_mpi_01.cc
@@ -45,7 +45,7 @@ test_mpi()
           unsigned int buf = numbers::invalid_unsigned_int;
           MPI_Status   status;
           MPI_Recv(&buf, 1, MPI_UNSIGNED, i, 1, MPI_COMM_WORLD, &status);
-          deallog << "got message '" << buf << "' from CPU " << i + 1 << "!"
+          deallog << "got message '" << buf << "' from CPU " << i + 1 << '!'
                   << std::endl;
           Assert(buf == i, ExcInternalError());
         }
diff --git a/tests/mpi/step-37.cc b/tests/mpi/step-37.cc
index e1d386fc30..d8992a0458 100644
--- a/tests/mpi/step-37.cc
+++ b/tests/mpi/step-37.cc
@@ -508,11 +508,11 @@ namespace Step37
           << "plot '-' using 1:2 with lines notitle, '-' with labels point pt 2 offset 1,1 notitle"
           << std::endl;
         GridOut().write_gnuplot(triangulation, f);
-        f << "e" << std::endl;
+        f << 'e' << std::endl;
 
         DoFTools::write_gnuplot_dof_support_point_info(f, support_points);
 
-        f << "e" << std::endl;
+        f << 'e' << std::endl;
       }
   }
 
diff --git a/tests/mpi/tria_ghost_owners_01.cc b/tests/mpi/tria_ghost_owners_01.cc
index add4762bbf..7d306c3fb2 100644
--- a/tests/mpi/tria_ghost_owners_01.cc
+++ b/tests/mpi/tria_ghost_owners_01.cc
@@ -88,7 +88,7 @@ test()
       for (std::set<types::subdomain_id>::iterator it = ghost_owners.begin();
            it != ghost_owners.end();
            ++it)
-        deallog << *it << " ";
+        deallog << *it << ' ';
       deallog << std::endl;
 
       mpi_check(ghost_owners);
@@ -100,7 +100,7 @@ test()
              level_ghost_owners.begin();
            it != level_ghost_owners.end();
            ++it)
-        deallog << *it << " ";
+        deallog << *it << ' ';
       deallog << std::endl;
 
       mpi_check(level_ghost_owners);
diff --git a/tests/mpi/tria_ghost_owners_02.cc b/tests/mpi/tria_ghost_owners_02.cc
index 6f21de0a6a..36fe88c61d 100644
--- a/tests/mpi/tria_ghost_owners_02.cc
+++ b/tests/mpi/tria_ghost_owners_02.cc
@@ -82,7 +82,7 @@ test()
       for (std::set<types::subdomain_id>::iterator it = ghost_owners.begin();
            it != ghost_owners.end();
            ++it)
-        deallog << *it << " ";
+        deallog << *it << ' ';
       deallog << std::endl;
 
       mpi_check(ghost_owners);
@@ -94,7 +94,7 @@ test()
              level_ghost_owners.begin();
            it != level_ghost_owners.end();
            ++it)
-        deallog << *it << " ";
+        deallog << *it << ' ';
       deallog << std::endl;
 
       mpi_check(level_ghost_owners);
diff --git a/tests/mpi/trilinos_ghost_01.cc b/tests/mpi/trilinos_ghost_01.cc
index 62e728e04b..137697ec49 100644
--- a/tests/mpi/trilinos_ghost_01.cc
+++ b/tests/mpi/trilinos_ghost_01.cc
@@ -59,8 +59,8 @@ test()
 
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
     {
-      deallog << myid * 2 << ":" << v(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << v(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << v(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << v(myid * 2 + 1) << std::endl;
     }
 
   Assert(v(myid * 2) == myid * 4.0, ExcInternalError());
diff --git a/tests/mpi/trilinos_ghost_05.cc b/tests/mpi/trilinos_ghost_05.cc
index f3dcc171e6..2d343059da 100644
--- a/tests/mpi/trilinos_ghost_05.cc
+++ b/tests/mpi/trilinos_ghost_05.cc
@@ -74,8 +74,8 @@ test()
 
   if (myid == 0)
     {
-      deallog << myid * 2 << ":" << v(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << v(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << v(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << v(myid * 2 + 1) << std::endl;
     }
 
   if (myid == 0)
diff --git a/tests/mpi/trilinos_sparse_matrix_02.cc b/tests/mpi/trilinos_sparse_matrix_02.cc
index b4a6a882c6..a517a721b1 100644
--- a/tests/mpi/trilinos_sparse_matrix_02.cc
+++ b/tests/mpi/trilinos_sparse_matrix_02.cc
@@ -83,15 +83,15 @@ test()
   double l1b = n_procs * 1.2;
 
   A.compress(VectorOperation::add);
-  deallog << "1: " << A.l1_norm() << " " << B.l1_norm() << " (should be " << l1a
+  deallog << "1: " << A.l1_norm() << ' ' << B.l1_norm() << " (should be " << l1a
           << " 0.0)" << std::endl;
 
   deallog << "set B=A..." << std::endl;
 
   B.copy_from(A);
 
-  deallog << "2: " << A.l1_norm() << " " << B.l1_norm() << " (should be " << l1a
-          << " " << l1a << ")" << std::endl;
+  deallog << "2: " << A.l1_norm() << ' ' << B.l1_norm() << " (should be " << l1a
+          << ' ' << l1a << ')' << std::endl;
 
   if (my_id == 0)
     {
@@ -104,8 +104,8 @@ test()
   A = 0;
   A.add(0, 0, -1.2);
   A.compress(VectorOperation::add);
-  deallog << "3: " << A.l1_norm() << " " << B.l1_norm() << " (should be " << l1b
-          << " " << l1a << ")" << std::endl;
+  deallog << "3: " << A.l1_norm() << ' ' << B.l1_norm() << " (should be " << l1b
+          << ' ' << l1a << ')' << std::endl;
 
   if (my_id == 0)
     {
diff --git a/tests/mpi/union_01.cc b/tests/mpi/union_01.cc
index 6fa5c3ae7d..c1ff2792d5 100644
--- a/tests/mpi/union_01.cc
+++ b/tests/mpi/union_01.cc
@@ -37,7 +37,7 @@ test(const MPI_Comm comm)
     const auto result = Utilities::MPI::compute_set_union(vector, comm);
 
     for (auto i : result)
-      deallog << i << " ";
+      deallog << i << ' ';
     deallog << std::endl;
   }
 
@@ -47,7 +47,7 @@ test(const MPI_Comm comm)
       std::set<unsigned int>(vector.begin(), vector.end()), comm);
 
     for (auto i : result)
-      deallog << i << " ";
+      deallog << i << ' ';
     deallog << std::endl;
   }
 }
diff --git a/tests/multigrid-global-coarsening/create_polynomial_coarsening_sequence_01.cc b/tests/multigrid-global-coarsening/create_polynomial_coarsening_sequence_01.cc
index c3331551bb..73d05cda16 100644
--- a/tests/multigrid-global-coarsening/create_polynomial_coarsening_sequence_01.cc
+++ b/tests/multigrid-global-coarsening/create_polynomial_coarsening_sequence_01.cc
@@ -32,7 +32,7 @@ test(
           i, type);
 
       for (const auto i : sequence)
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/multigrid-global-coarsening/mg_transfer_support_01.cc b/tests/multigrid-global-coarsening/mg_transfer_support_01.cc
index 0db7f8ac37..c95077c04f 100644
--- a/tests/multigrid-global-coarsening/mg_transfer_support_01.cc
+++ b/tests/multigrid-global-coarsening/mg_transfer_support_01.cc
@@ -29,7 +29,7 @@ test()
       for (unsigned int j = 1; j < 25; ++j)
         if (MGTwoLevelTransfer<2, LinearAlgebra::distributed::Vector<double>>::
               fast_polynomial_transfer_supported(i, j))
-          deallog << 1 << " ";
+          deallog << 1 << ' ';
         else
           deallog << "  ";
       deallog << std::endl;
diff --git a/tests/multigrid-global-coarsening/multigrid_a_01.cc b/tests/multigrid-global-coarsening/multigrid_a_01.cc
index 302aafb0a9..3eee8f4e89 100644
--- a/tests/multigrid-global-coarsening/multigrid_a_01.cc
+++ b/tests/multigrid-global-coarsening/multigrid_a_01.cc
@@ -124,8 +124,8 @@ test(const unsigned int n_refinements,
            operators,
            transfer);
 
-  deallog << dim << " " << fe_degree_fine << " " << n_refinements << " "
-          << (do_simplex_mesh ? "tri " : "quad") << " "
+  deallog << dim << ' ' << fe_degree_fine << ' ' << n_refinements << ' '
+          << (do_simplex_mesh ? "tri " : "quad") << ' '
           << solver_control.last_step() << std::endl;
 
   static unsigned int counter = 0;
diff --git a/tests/multigrid-global-coarsening/multigrid_a_02.cc b/tests/multigrid-global-coarsening/multigrid_a_02.cc
index b8ccd60ae2..32acb24c11 100644
--- a/tests/multigrid-global-coarsening/multigrid_a_02.cc
+++ b/tests/multigrid-global-coarsening/multigrid_a_02.cc
@@ -113,7 +113,7 @@ test(const unsigned int n_refinements, const unsigned int fe_degree_fine)
 
   constraints[max_level].distribute(dst);
 
-  deallog << dim << " " << fe_degree_fine << " " << n_refinements << " "
+  deallog << dim << ' ' << fe_degree_fine << ' ' << n_refinements << ' '
           << solver_control.last_step() << std::endl;
 
   return;
diff --git a/tests/multigrid-global-coarsening/multigrid_p_01.cc b/tests/multigrid-global-coarsening/multigrid_p_01.cc
index 3a86150a4f..3d5034d4d5 100644
--- a/tests/multigrid-global-coarsening/multigrid_p_01.cc
+++ b/tests/multigrid-global-coarsening/multigrid_p_01.cc
@@ -154,8 +154,8 @@ test(const unsigned int n_refinements,
 
   constraints[max_level].distribute(dst);
 
-  deallog << dim << " " << fe_degree_fine << " " << n_refinements << " "
-          << (do_simplex_mesh ? "tri " : "quad") << " "
+  deallog << dim << ' ' << fe_degree_fine << ' ' << n_refinements << ' '
+          << (do_simplex_mesh ? "tri " : "quad") << ' '
           << solver_control.last_step() << std::endl;
 
   static unsigned int counter = 0;
diff --git a/tests/multigrid-global-coarsening/multigrid_p_02.cc b/tests/multigrid-global-coarsening/multigrid_p_02.cc
index cc30f93f23..cee4df9438 100644
--- a/tests/multigrid-global-coarsening/multigrid_p_02.cc
+++ b/tests/multigrid-global-coarsening/multigrid_p_02.cc
@@ -130,7 +130,7 @@ test(const unsigned int n_refinements, const unsigned int fe_degree_fine)
 
   constraints[max_level].distribute(dst);
 
-  deallog << dim << " " << fe_degree_fine << " " << n_refinements << " "
+  deallog << dim << ' ' << fe_degree_fine << ' ' << n_refinements << ' '
           << solver_control.last_step() << std::endl;
 
   return;
diff --git a/tests/multigrid-global-coarsening/multigrid_p_03.cc b/tests/multigrid-global-coarsening/multigrid_p_03.cc
index 3af75fdf7e..dfe887d643 100644
--- a/tests/multigrid-global-coarsening/multigrid_p_03.cc
+++ b/tests/multigrid-global-coarsening/multigrid_p_03.cc
@@ -132,8 +132,8 @@ test(const unsigned int n_refinements,
 
   constraints[max_level].distribute(dst);
 
-  deallog << dim << " " << fe_degree_fine << " " << n_refinements << " "
-          << level << " " << dst.size() << " " << solver_control.last_step()
+  deallog << dim << ' ' << fe_degree_fine << ' ' << n_refinements << ' '
+          << level << ' ' << dst.size() << ' ' << solver_control.last_step()
           << std::endl;
 
   return;
diff --git a/tests/multigrid/constrained_dofs_01.cc b/tests/multigrid/constrained_dofs_01.cc
index 68b80b0fe2..843aa2fc51 100644
--- a/tests/multigrid/constrained_dofs_01.cc
+++ b/tests/multigrid/constrained_dofs_01.cc
@@ -137,7 +137,7 @@ check_fe(FiniteElement<dim> &fe)
   const unsigned int n_levels = tr.n_global_levels();
   for (unsigned int level = 0; level < n_levels; ++level)
     {
-      deallog << "Level " << level << ":" << std::endl;
+      deallog << "Level " << level << ':' << std::endl;
 
       IndexSet rei = mg_constrained_dofs.get_refinement_edge_indices(level);
       deallog << "get_refinement_edge_indices:" << std::endl;
diff --git a/tests/multigrid/constrained_dofs_02.cc b/tests/multigrid/constrained_dofs_02.cc
index 1449eac89b..f8ec387cf4 100644
--- a/tests/multigrid/constrained_dofs_02.cc
+++ b/tests/multigrid/constrained_dofs_02.cc
@@ -197,7 +197,7 @@ check_fe(FiniteElement<dim> &fe)
   const unsigned int n_levels = tr.n_global_levels();
   for (unsigned int level = 0; level < n_levels; ++level)
     {
-      deallog << "Level " << level << ":" << std::endl;
+      deallog << "Level " << level << ':' << std::endl;
 
       IndexSet rei = mg_constrained_dofs.get_refinement_edge_indices(level);
       deallog << "get_refinement_edge_indices:" << std::endl;
diff --git a/tests/multigrid/constrained_dofs_03.cc b/tests/multigrid/constrained_dofs_03.cc
index 64ab84b6a8..354804255c 100644
--- a/tests/multigrid/constrained_dofs_03.cc
+++ b/tests/multigrid/constrained_dofs_03.cc
@@ -70,7 +70,7 @@ check_fe(FiniteElement<dim> &fe, ComponentMask &component_mask)
   const unsigned int n_levels = tr.n_global_levels();
   for (unsigned int level = 0; level < n_levels; ++level)
     {
-      deallog << "Level " << level << ":" << std::endl;
+      deallog << "Level " << level << ':' << std::endl;
       IndexSet boundary_indices =
         mg_constrained_dofs.get_boundary_indices(level);
       boundary_indices.print(deallog);
diff --git a/tests/multigrid/mg_renumbered_03.cc b/tests/multigrid/mg_renumbered_03.cc
index 426a292d90..63e6895f36 100644
--- a/tests/multigrid/mg_renumbered_03.cc
+++ b/tests/multigrid/mg_renumbered_03.cc
@@ -377,11 +377,11 @@ LaplaceProblem<dim>::test()
   for (unsigned int l = 0; l < triangulation.n_levels(); ++l)
     {
       diff(d[l], mg_dof_handler_renumbered, u[l], l);
-      deallog << l << " " << u[l].l2_norm() << '\t' << v[l].l2_norm() << '\t'
+      deallog << l << ' ' << u[l].l2_norm() << '\t' << v[l].l2_norm() << '\t'
               << d[l].l2_norm() << std::endl;
       for (unsigned int i = 0; i < d[l].size(); ++i)
         if (d[l](i) != 0)
-          deallog << i << " " << d[l](i) << std::endl;
+          deallog << i << ' ' << d[l](i) << std::endl;
     }
   output_gpl(mg_dof_handler_renumbered, d);
 }
diff --git a/tests/multigrid/renumbering_04.cc b/tests/multigrid/renumbering_04.cc
index 1ac6ebbbef..85edec8d95 100644
--- a/tests/multigrid/renumbering_04.cc
+++ b/tests/multigrid/renumbering_04.cc
@@ -65,10 +65,10 @@ check(FiniteElement<dim> &fe)
              cell != dh.end(level);
              ++cell)
           {
-            deallog << "cell " << cell->id() << ":" << std::endl;
+            deallog << "cell " << cell->id() << ':' << std::endl;
             cell->get_mg_dof_indices(local_dofs);
             for (unsigned int i = 0; i < n_dofs_per_cell; ++i)
-              deallog << local_dofs[i] << " ";
+              deallog << local_dofs[i] << ' ';
             deallog << std::endl;
           }
       }
@@ -88,10 +88,10 @@ check(FiniteElement<dim> &fe)
              cell != dh.end(level);
              ++cell)
           {
-            deallog << "cell " << cell->id() << ":" << std::endl;
+            deallog << "cell " << cell->id() << ':' << std::endl;
             cell->get_mg_dof_indices(local_dofs);
             for (unsigned int i = 0; i < n_dofs_per_cell; ++i)
-              deallog << local_dofs[i] << " ";
+              deallog << local_dofs[i] << ' ';
             deallog << std::endl;
           }
       }
diff --git a/tests/multigrid/renumbering_05.cc b/tests/multigrid/renumbering_05.cc
index add1c08762..57839e523d 100644
--- a/tests/multigrid/renumbering_05.cc
+++ b/tests/multigrid/renumbering_05.cc
@@ -45,7 +45,7 @@ print_dof_numbers(const DoFHandler<dim> &dof)
         cell->get_dof_indices(dof_indices);
         deallog << "cell " << cell->id() << ": ";
         for (types::global_dof_index i : dof_indices)
-          deallog << i << " ";
+          deallog << i << ' ';
         deallog << std::endl;
       }
   for (unsigned int l = 0; l < dof.get_triangulation().n_global_levels(); ++l)
@@ -57,7 +57,7 @@ print_dof_numbers(const DoFHandler<dim> &dof)
             cell->get_mg_dof_indices(dof_indices);
             deallog << "cell " << cell->id() << ": ";
             for (types::global_dof_index i : dof_indices)
-              deallog << i << " ";
+              deallog << i << ' ';
             deallog << std::endl;
           }
     }
diff --git a/tests/multigrid/renumbering_06.cc b/tests/multigrid/renumbering_06.cc
index b5e110a7da..f165e216c1 100644
--- a/tests/multigrid/renumbering_06.cc
+++ b/tests/multigrid/renumbering_06.cc
@@ -52,7 +52,7 @@ print_dof_numbers(const DoFHandler<dim> &dof)
         cell->get_dof_indices(dof_indices);
         deallog << "cell " << cell->id() << ": ";
         for (types::global_dof_index i : dof_indices)
-          deallog << i << " ";
+          deallog << i << ' ';
         deallog << std::endl;
       }
   for (unsigned int l = 0; l < dof.get_triangulation().n_global_levels(); ++l)
@@ -64,7 +64,7 @@ print_dof_numbers(const DoFHandler<dim> &dof)
             cell->get_mg_dof_indices(dof_indices);
             deallog << "cell " << cell->id() << ": ";
             for (types::global_dof_index i : dof_indices)
-              deallog << i << " ";
+              deallog << i << ' ';
             deallog << std::endl;
           }
     }
diff --git a/tests/multigrid/renumbering_07.cc b/tests/multigrid/renumbering_07.cc
index 83e5ec1606..1be207cf57 100644
--- a/tests/multigrid/renumbering_07.cc
+++ b/tests/multigrid/renumbering_07.cc
@@ -52,7 +52,7 @@ print_dof_numbers(const DoFHandler<dim> &dof)
         cell->get_dof_indices(dof_indices);
         deallog << "cell " << cell->id() << ": ";
         for (types::global_dof_index i : dof_indices)
-          deallog << i << " ";
+          deallog << i << ' ';
         deallog << std::endl;
       }
   for (unsigned int l = 0; l < dof.get_triangulation().n_global_levels(); ++l)
@@ -64,7 +64,7 @@ print_dof_numbers(const DoFHandler<dim> &dof)
             cell->get_mg_dof_indices(dof_indices);
             deallog << "cell " << cell->id() << ": ";
             for (types::global_dof_index i : dof_indices)
-              deallog << i << " ";
+              deallog << i << ' ';
             deallog << std::endl;
           }
     }
diff --git a/tests/multigrid/renumbering_08.cc b/tests/multigrid/renumbering_08.cc
index 0e94f8d065..b0185cf73d 100644
--- a/tests/multigrid/renumbering_08.cc
+++ b/tests/multigrid/renumbering_08.cc
@@ -45,7 +45,7 @@ print_dof_numbers(const DoFHandler<dim> &dof)
         cell->get_dof_indices(dof_indices);
         deallog << "cell " << cell->id() << ": ";
         for (types::global_dof_index i : dof_indices)
-          deallog << i << " ";
+          deallog << i << ' ';
         deallog << std::endl;
       }
   for (unsigned int l = 0; l < dof.get_triangulation().n_global_levels(); ++l)
@@ -57,7 +57,7 @@ print_dof_numbers(const DoFHandler<dim> &dof)
             cell->get_mg_dof_indices(dof_indices);
             deallog << "cell " << cell->id() << ": ";
             for (types::global_dof_index i : dof_indices)
-              deallog << i << " ";
+              deallog << i << ' ';
             deallog << std::endl;
           }
     }
diff --git a/tests/multigrid/step-16-07.cc b/tests/multigrid/step-16-07.cc
index 43b966d7af..6401b42679 100644
--- a/tests/multigrid/step-16-07.cc
+++ b/tests/multigrid/step-16-07.cc
@@ -399,7 +399,7 @@ LaplaceProblem<dim>::assemble_multigrid()
           else
             {
               cell_matrix(i, j) = 0;
-              std::cout << i << " " << j << "\n";
+              std::cout << i << ' ' << j << "\n";
             }
 
 
diff --git a/tests/multigrid/step-16-08.cc b/tests/multigrid/step-16-08.cc
index 04da0ce19f..a640d6aff9 100644
--- a/tests/multigrid/step-16-08.cc
+++ b/tests/multigrid/step-16-08.cc
@@ -406,7 +406,7 @@ LaplaceProblem<dim>::assemble_multigrid()
           else
             {
               cell_matrix(i, j) = 0;
-              std::cout << i << " " << j << "\n";
+              std::cout << i << ' ' << j << "\n";
             }
 
 
diff --git a/tests/multigrid/step-16.cc b/tests/multigrid/step-16.cc
index 96f506813d..3dc03fdd8e 100644
--- a/tests/multigrid/step-16.cc
+++ b/tests/multigrid/step-16.cc
@@ -399,7 +399,7 @@ LaplaceProblem<dim>::assemble_multigrid()
           else
             {
               cell_matrix(i, j) = 0;
-              std::cout << i << " " << j << "\n";
+              std::cout << i << ' ' << j << "\n";
             }
 
 
diff --git a/tests/multigrid/step-50_01.cc b/tests/multigrid/step-50_01.cc
index d576c2252a..01abedfa56 100644
--- a/tests/multigrid/step-50_01.cc
+++ b/tests/multigrid/step-50_01.cc
@@ -423,10 +423,10 @@ namespace Step50
     for (unsigned int i = 0; i < triangulation.n_global_levels(); ++i)
       {
         mg_matrices[i].compress(VectorOperation::add);
-        deallog << "mg_mat" << i << " " << mg_matrices[i].frobenius_norm()
+        deallog << "mg_mat" << i << ' ' << mg_matrices[i].frobenius_norm()
                 << std::endl;
         mg_interface_matrices[i].compress(VectorOperation::add);
-        deallog << "mg_interface_mat" << i << " "
+        deallog << "mg_interface_mat" << i << ' '
                 << mg_interface_matrices[i].frobenius_norm() << std::endl;
       }
   }
diff --git a/tests/multigrid/transfer_04a.cc b/tests/multigrid/transfer_04a.cc
index 13aef01078..6ed4942217 100644
--- a/tests/multigrid/transfer_04a.cc
+++ b/tests/multigrid/transfer_04a.cc
@@ -157,7 +157,7 @@ check_fe(FiniteElement<dim> &fe)
     for (unsigned int i = 0; i < dofh.locally_owned_dofs().n_elements(); ++i)
       {
         unsigned int index = dofh.locally_owned_dofs().nth_index_in_set(i);
-        deallog << v[index] << " ";
+        deallog << v[index] << ' ';
       }
   }
   // v.print(deallog.get_file_stream());
diff --git a/tests/multigrid/transfer_04b.cc b/tests/multigrid/transfer_04b.cc
index aa4f1c38a8..9e1633594a 100644
--- a/tests/multigrid/transfer_04b.cc
+++ b/tests/multigrid/transfer_04b.cc
@@ -157,7 +157,7 @@ check_fe(FiniteElement<dim> &fe)
     for (unsigned int i = 0; i < dofh.locally_owned_dofs().n_elements(); ++i)
       {
         unsigned int index = dofh.locally_owned_dofs().nth_index_in_set(i);
-        deallog << static_cast<PetscScalar>(v(index)) << " ";
+        deallog << static_cast<PetscScalar>(v(index)) << ' ';
       }
   }
   // v.print(deallog.get_file_stream());
diff --git a/tests/multigrid/transfer_matrix_free_04.cc b/tests/multigrid/transfer_matrix_free_04.cc
index f1a58066e2..e1f88c5e04 100644
--- a/tests/multigrid/transfer_matrix_free_04.cc
+++ b/tests/multigrid/transfer_matrix_free_04.cc
@@ -105,7 +105,7 @@ check(const unsigned int fe_degree)
           deallog << "Diff prolongate   l" << level << ": "
                   << filter_out_small_numbers(v3.l2_norm(), tolerance)
                   << std::endl;
-          deallog << "Vectors have ghosts: " << v2.has_ghost_elements() << " "
+          deallog << "Vectors have ghosts: " << v2.has_ghost_elements() << ' '
                   << v3.has_ghost_elements() << std::endl;
         }
 
diff --git a/tests/multigrid/transfer_matrix_free_13.cc b/tests/multigrid/transfer_matrix_free_13.cc
index cf59a582cd..aa2dd97480 100644
--- a/tests/multigrid/transfer_matrix_free_13.cc
+++ b/tests/multigrid/transfer_matrix_free_13.cc
@@ -75,7 +75,7 @@ check()
   deallog << "SRC Vector" << std::endl;
   LinearAlgebra::distributed::Vector<double> src_level_0(mgdof.n_dofs(0));
   for (unsigned int i = 0; i < mgdof.n_dofs(0); ++i)
-    deallog << src_level_0(i) << " ";
+    deallog << src_level_0(i) << ' ';
   deallog << std::endl << std::endl;
 
   {
@@ -83,7 +83,7 @@ check()
     transfer_mf.prolongate(1, dst_level_1, src_level_0);
     deallog << "DST Vector" << std::endl;
     for (unsigned int i = 0; i < mgdof.n_dofs(1); ++i)
-      deallog << dst_level_1(i) << " ";
+      deallog << dst_level_1(i) << ' ';
     deallog << std::endl;
   }
 }
diff --git a/tests/multigrid/transfer_prebuilt_05.cc b/tests/multigrid/transfer_prebuilt_05.cc
index 8892e90bdf..0410fcca5f 100644
--- a/tests/multigrid/transfer_prebuilt_05.cc
+++ b/tests/multigrid/transfer_prebuilt_05.cc
@@ -72,7 +72,7 @@ check()
   deallog << "SRC Vector" << std::endl;
   Vector<double> src_level_0(mgdof.n_dofs(0));
   for (unsigned int i = 0; i < mgdof.n_dofs(0); ++i)
-    deallog << src_level_0(i) << " ";
+    deallog << src_level_0(i) << ' ';
   deallog << std::endl << std::endl;
 
   {
@@ -80,7 +80,7 @@ check()
     transfer_pb.prolongate(1, dst_level_1, src_level_0);
     deallog << "DST Vector" << std::endl;
     for (unsigned int i = 0; i < mgdof.n_dofs(1); ++i)
-      deallog << dst_level_1(i) << " ";
+      deallog << dst_level_1(i) << ' ';
     deallog << std::endl;
   }
 }
diff --git a/tests/multithreading/bench_01.cc b/tests/multithreading/bench_01.cc
index f315883a9d..5f4b08e138 100644
--- a/tests/multithreading/bench_01.cc
+++ b/tests/multithreading/bench_01.cc
@@ -383,7 +383,7 @@ assemble()
   const unsigned int n_phys_cores =
     std::min(n_max_threads, MultithreadInfo::n_cores());
   std::cout << "MultithreadInfo::n_cores()=" << n_phys_cores
-            << " (limited from " << MultithreadInfo::n_cores() << ")"
+            << " (limited from " << MultithreadInfo::n_cores() << ')'
             << std::endl;
   std::cout << "MultithreadInfo::n_threads()=" << MultithreadInfo::n_threads()
             << std::endl;
@@ -428,7 +428,7 @@ assemble()
         timer.stop();
         const double time = timer.last_wall_time();
         avg += time;
-        std::cout << time << " " << std::flush;
+        std::cout << time << ' ' << std::flush;
         reference_l2 = system_rhs.l2_norm();
       }
     avg /= n_runs;
@@ -486,7 +486,7 @@ assemble()
             timer.stop();
             const double time = timer.last_wall_time();
             avg += time;
-            std::cout << time << " " << std::flush;
+            std::cout << time << ' ' << std::flush;
             Assert(abs(reference_l2 - system_rhs.l2_norm()) < 1e-10,
                    ExcInternalError());
           }
@@ -527,7 +527,7 @@ assemble()
             timer.stop();
             const double time = timer.last_wall_time();
             avg += time;
-            std::cout << time << " " << std::flush;
+            std::cout << time << ' ' << std::flush;
             Assert(abs(reference_l2 - system_rhs.l2_norm()) < 1e-10,
                    ExcInternalError());
           }
@@ -561,7 +561,7 @@ assemble()
             timer.stop();
             const double time = timer.last_wall_time();
             avg += time;
-            std::cout << time << " " << std::flush;
+            std::cout << time << ' ' << std::flush;
             Assert(abs(reference_l2 - system_rhs.l2_norm()) < 1e-10,
                    ExcInternalError());
           }
@@ -597,7 +597,7 @@ assemble()
             timer.stop();
             const double time = timer.last_wall_time();
             avg += time;
-            std::cout << time << " " << std::flush;
+            std::cout << time << ' ' << std::flush;
             Assert(abs(reference_l2 - system_rhs.l2_norm()) < 1e-10,
                    ExcInternalError());
           }
@@ -630,7 +630,7 @@ assemble()
             timer.stop();
             const double time = timer.last_wall_time();
             avg += time;
-            std::cout << time << " " << std::flush;
+            std::cout << time << ' ' << std::flush;
             Assert(abs(reference_l2 - system_rhs.l2_norm()) < 1e-10,
                    ExcInternalError());
           }
diff --git a/tests/non_matching/mesh_classifier.cc b/tests/non_matching/mesh_classifier.cc
index 09d2b7d475..5188877a6b 100644
--- a/tests/non_matching/mesh_classifier.cc
+++ b/tests/non_matching/mesh_classifier.cc
@@ -81,7 +81,7 @@ print_cell_and_face_locations(
     {
       const NonMatching::LocationToLevelSet cell_position =
         classifier.location_to_level_set(cell, i);
-      deallog << "face " << i << " " << location_to_string(cell_position)
+      deallog << "face " << i << ' ' << location_to_string(cell_position)
               << std::endl;
     }
 }
diff --git a/tests/numerics/error_estimator_02.cc b/tests/numerics/error_estimator_02.cc
index 23eb2344d8..18bc3e7bdd 100644
--- a/tests/numerics/error_estimator_02.cc
+++ b/tests/numerics/error_estimator_02.cc
@@ -294,7 +294,7 @@ test_neumann(const NeumanBC<dim> &func)
 
   dealii::deallog << "dof values:" << std::endl;
   for (unsigned int i = 0; i < values.size(); ++i)
-    dealii::deallog << " " << values[i];
+    dealii::deallog << ' ' << values[i];
   dealii::deallog << std::endl;
 
   // call Kelly
@@ -317,7 +317,7 @@ test_neumann(const NeumanBC<dim> &func)
 
   dealii::deallog << "error:" << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
-    dealii::deallog << " " << error[i];
+    dealii::deallog << ' ' << error[i];
   dealii::deallog << std::endl;
 
   // output("neuman.vtu",
@@ -330,7 +330,7 @@ test_neumann(const NeumanBC<dim> &func)
   get_h_area<dim>(h, A, L);
   const double expected_value_squared = h * A * std::pow(func.get_c(), 2) / p;
   dealii::deallog << "expected:" << std::endl
-                  << " " << std::sqrt(expected_value_squared) << std::endl;
+                  << ' ' << std::sqrt(expected_value_squared) << std::endl;
 
   AssertThrow(std::fabs(std::sqrt(expected_value_squared) - error[0]) < 1e-5,
               dealii::ExcInternalError());
@@ -411,7 +411,7 @@ test_regular(const MyFunction<dim> &func)
 
   dealii::deallog << "dof values:" << std::endl;
   for (unsigned int i = 0; i < values.size(); ++i)
-    dealii::deallog << " " << values[i];
+    dealii::deallog << ' ' << values[i];
   dealii::deallog << std::endl;
 
   // call Kelly
@@ -431,7 +431,7 @@ test_regular(const MyFunction<dim> &func)
 
   dealii::deallog << "error:" << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
-    dealii::deallog << " " << error[i];
+    dealii::deallog << ' ' << error[i];
   dealii::deallog << std::endl;
 
   // output("regular.vtu",
@@ -445,7 +445,7 @@ test_regular(const MyFunction<dim> &func)
   const double expected_value_squared =
     h * A * std::pow(func.get_k(), 2) / 2.0 / std::max(p1, p2);
   dealii::deallog << "expected:" << std::endl
-                  << " " << std::sqrt(expected_value_squared) << std::endl;
+                  << ' ' << std::sqrt(expected_value_squared) << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
     AssertThrow(std::fabs(std::sqrt(expected_value_squared) - error[i]) < 1e-6,
                 dealii::ExcInternalError());
@@ -542,7 +542,7 @@ test_irregular(const MyFunction<dim> &func)
 
   dealii::deallog << "dof values:" << std::endl;
   for (unsigned int i = 0; i < values.size(); ++i)
-    dealii::deallog << " " << values[i];
+    dealii::deallog << ' ' << values[i];
   dealii::deallog << std::endl;
 
   // call Kelly
@@ -562,7 +562,7 @@ test_irregular(const MyFunction<dim> &func)
 
   dealii::deallog << "error:" << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
-    dealii::deallog << " " << error[i];
+    dealii::deallog << ' ' << error[i];
   dealii::deallog << std::endl;
 
   // output("irregular.vtu",
@@ -596,7 +596,7 @@ test_irregular(const MyFunction<dim> &func)
 
   dealii::deallog << "expected:" << std::endl;
   for (unsigned int i = 0; i < expected_error.size(); ++i)
-    deallog << " " << expected_error[i];
+    deallog << ' ' << expected_error[i];
   deallog << std::endl;
 
   for (unsigned int i = 0; i < expected_error.size(); ++i)
@@ -712,7 +712,7 @@ test(const MySecondFunction<dim> &func)
 
   dealii::deallog << "dof values:" << std::endl;
   for (unsigned int i = 0; i < values.size(); ++i)
-    dealii::deallog << " " << values[i];
+    dealii::deallog << ' ' << values[i];
   dealii::deallog << std::endl;
 
   // call Kelly
@@ -732,7 +732,7 @@ test(const MySecondFunction<dim> &func)
 
   dealii::deallog << "error:" << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
-    dealii::deallog << " " << error[i];
+    dealii::deallog << ' ' << error[i];
   dealii::deallog << std::endl;
 
   dof_handler.clear();
diff --git a/tests/numerics/error_estimator_02_complex.cc b/tests/numerics/error_estimator_02_complex.cc
index 88bdc2f7c7..ac4e97f796 100644
--- a/tests/numerics/error_estimator_02_complex.cc
+++ b/tests/numerics/error_estimator_02_complex.cc
@@ -238,7 +238,7 @@ test_neumann(const NeumanBC<dim> &func)
 
   dealii::deallog << "dof values:" << std::endl;
   for (unsigned int i = 0; i < values.size(); ++i)
-    dealii::deallog << " " << values[i];
+    dealii::deallog << ' ' << values[i];
   dealii::deallog << std::endl;
 
   // call Kelly
@@ -262,7 +262,7 @@ test_neumann(const NeumanBC<dim> &func)
 
   dealii::deallog << "error:" << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
-    dealii::deallog << " " << error[i];
+    dealii::deallog << ' ' << error[i];
   dealii::deallog << std::endl;
 
   // output("neuman.vtu",
@@ -275,7 +275,7 @@ test_neumann(const NeumanBC<dim> &func)
   get_h_area<dim>(h, A, L);
   const double expected_value_squared = h * A * std::pow(func.get_c(), 2) / p;
   dealii::deallog << "expected:" << std::endl
-                  << " " << std::sqrt(expected_value_squared) << std::endl;
+                  << ' ' << std::sqrt(expected_value_squared) << std::endl;
 
   AssertThrow(std::fabs(std::sqrt(expected_value_squared) - error[0]) < 1e-5,
               dealii::ExcInternalError());
@@ -356,7 +356,7 @@ test_regular(const MyFunction<dim> &func)
 
   dealii::deallog << "dof values:" << std::endl;
   for (unsigned int i = 0; i < values.size(); ++i)
-    dealii::deallog << " " << values[i];
+    dealii::deallog << ' ' << values[i];
   dealii::deallog << std::endl;
 
   // call Kelly
@@ -376,7 +376,7 @@ test_regular(const MyFunction<dim> &func)
 
   dealii::deallog << "error:" << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
-    dealii::deallog << " " << error[i];
+    dealii::deallog << ' ' << error[i];
   dealii::deallog << std::endl;
 
   // output("regular.vtu",
@@ -390,7 +390,7 @@ test_regular(const MyFunction<dim> &func)
   const double expected_value_squared =
     h * A * std::pow(func.get_k(), 2) / 2.0 / std::max(p1, p2);
   dealii::deallog << "expected:" << std::endl
-                  << " " << std::sqrt(expected_value_squared) << std::endl;
+                  << ' ' << std::sqrt(expected_value_squared) << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
     AssertThrow(std::fabs(std::sqrt(expected_value_squared) - error[i]) < 1e-6,
                 dealii::ExcInternalError());
@@ -487,7 +487,7 @@ test_irregular(const MyFunction<dim> &func)
 
   dealii::deallog << "dof values:" << std::endl;
   for (unsigned int i = 0; i < values.size(); ++i)
-    dealii::deallog << " " << values[i];
+    dealii::deallog << ' ' << values[i];
   dealii::deallog << std::endl;
 
   // call Kelly
@@ -507,7 +507,7 @@ test_irregular(const MyFunction<dim> &func)
 
   dealii::deallog << "error:" << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
-    dealii::deallog << " " << error[i];
+    dealii::deallog << ' ' << error[i];
   dealii::deallog << std::endl;
 
   // output("irregular.vtu",
@@ -541,7 +541,7 @@ test_irregular(const MyFunction<dim> &func)
 
   dealii::deallog << "expected:" << std::endl;
   for (unsigned int i = 0; i < expected_error.size(); ++i)
-    deallog << " " << expected_error[i];
+    deallog << ' ' << expected_error[i];
   deallog << std::endl;
 
   for (unsigned int i = 0; i < expected_error.size(); ++i)
@@ -659,7 +659,7 @@ test(const MySecondFunction<dim> &func)
 
   dealii::deallog << "dof values:" << std::endl;
   for (unsigned int i = 0; i < values.size(); ++i)
-    dealii::deallog << " " << values[i];
+    dealii::deallog << ' ' << values[i];
   dealii::deallog << std::endl;
 
   // call Kelly
@@ -679,7 +679,7 @@ test(const MySecondFunction<dim> &func)
 
   dealii::deallog << "error:" << std::endl;
   for (unsigned int i = 0; i < error.size(); ++i)
-    dealii::deallog << " " << error[i];
+    dealii::deallog << ' ' << error[i];
   dealii::deallog << std::endl;
 
   dof_handler.clear();
diff --git a/tests/numerics/interpolate_to_different_mesh_01.cc b/tests/numerics/interpolate_to_different_mesh_01.cc
index 332f6783c5..3f38d954ea 100644
--- a/tests/numerics/interpolate_to_different_mesh_01.cc
+++ b/tests/numerics/interpolate_to_different_mesh_01.cc
@@ -88,7 +88,7 @@ check(const unsigned int refinement_1, const unsigned int refinement_2)
           unit_support_point = cell->get_fe().unit_support_point(shapefun);
           support_point =
             mapping.transform_unit_to_real_cell(cell, unit_support_point);
-          deallog << " " << support_point << ":\n "
+          deallog << ' ' << support_point << ":\n "
                   << u_1[local_dof_indices[shapefun]] << endl
                   << endl;
         }
@@ -105,7 +105,7 @@ check(const unsigned int refinement_1, const unsigned int refinement_2)
           unit_support_point = cell->get_fe().unit_support_point(shapefun);
           support_point =
             mapping.transform_unit_to_real_cell(cell, unit_support_point);
-          deallog << " " << support_point << ":\n "
+          deallog << ' ' << support_point << ":\n "
                   << u_2[local_dof_indices[shapefun]] << endl
                   << endl;
         }
diff --git a/tests/numerics/interpolate_to_different_mesh_02.cc b/tests/numerics/interpolate_to_different_mesh_02.cc
index bcc2859296..51b01a9115 100644
--- a/tests/numerics/interpolate_to_different_mesh_02.cc
+++ b/tests/numerics/interpolate_to_different_mesh_02.cc
@@ -102,7 +102,7 @@ check(const unsigned int refinement_1, const unsigned int refinement_2)
           unit_support_point = cell->get_fe().unit_support_point(shapefun);
           support_point =
             mapping.transform_unit_to_real_cell(cell, unit_support_point);
-          deallog << " " << support_point << ":\n "
+          deallog << ' ' << support_point << ":\n "
                   << u_1[local_dof_indices_1[shapefun]] << endl
                   << endl;
         }
@@ -118,7 +118,7 @@ check(const unsigned int refinement_1, const unsigned int refinement_2)
           unit_support_point = cell->get_fe().unit_support_point(shapefun);
           support_point =
             mapping.transform_unit_to_real_cell(cell, unit_support_point);
-          deallog << " " << support_point << ":\n "
+          deallog << ' ' << support_point << ":\n "
                   << u_2[local_dof_indices_2[shapefun]] << endl
                   << endl;
         }
diff --git a/tests/numerics/project_boundary_01.cc b/tests/numerics/project_boundary_01.cc
index 5a22a36c35..0117a95d2f 100644
--- a/tests/numerics/project_boundary_01.cc
+++ b/tests/numerics/project_boundary_01.cc
@@ -102,7 +102,7 @@ write_map(const std::map<types::global_dof_index, double> &bv)
        i != bv.end();
        ++i)
     // also output log of value to also display small numbers
-    deallog << i->first << ' ' << i->second << " "
+    deallog << i->first << ' ' << i->second << ' '
             << (std::abs(i->second) > 0 ? std::log(std::abs(i->second)) :
                                           -10000)
             << std::endl;
diff --git a/tests/numerics/project_to_surface_01.cc b/tests/numerics/project_to_surface_01.cc
index eea4eaa34c..b611c43a10 100644
--- a/tests/numerics/project_to_surface_01.cc
+++ b/tests/numerics/project_to_surface_01.cc
@@ -118,7 +118,7 @@ test()
           else
             deallog << cell->vertex(1);
 
-          deallog << ")" << std::endl;
+          deallog << ')' << std::endl;
         }
       tria.clear();
     }
diff --git a/tests/numerics/project_to_surface_02.cc b/tests/numerics/project_to_surface_02.cc
index 266c651ec1..97926ac8f0 100644
--- a/tests/numerics/project_to_surface_02.cc
+++ b/tests/numerics/project_to_surface_02.cc
@@ -140,7 +140,7 @@ test()
           deallog << quad->vertex(2);
           deallog << " to ";
           deallog << quad->vertex(3);
-          deallog << ")" << std::endl;
+          deallog << ')' << std::endl;
 
           // now make sure that p is
           // indeed closer to
diff --git a/tests/numerics/project_to_surface_03.cc b/tests/numerics/project_to_surface_03.cc
index 075858b97f..cde841638a 100644
--- a/tests/numerics/project_to_surface_03.cc
+++ b/tests/numerics/project_to_surface_03.cc
@@ -105,7 +105,7 @@ test()
           deallog << quad->vertex(2);
           deallog << " to ";
           deallog << quad->vertex(3);
-          deallog << ")" << std::endl;
+          deallog << ')' << std::endl;
 
           // now make sure that p is
           // indeed closer to
diff --git a/tests/opencascade/closest_point_to_shape.cc b/tests/opencascade/closest_point_to_shape.cc
index 14a2759a5b..83d87fb9a3 100644
--- a/tests/opencascade/closest_point_to_shape.cc
+++ b/tests/opencascade/closest_point_to_shape.cc
@@ -82,7 +82,7 @@ main()
       v           = std::get<3>(ref);
 
       deallog << "Origin: " << points[i] << ", on unit circle: " << pp
-              << ", with local coordinates (u, v): (" << u << ", " << v << ")"
+              << ", with local coordinates (u, v): (" << u << ", " << v << ')'
               << std::endl;
     }
   return 0;
diff --git a/tests/opencascade/interpolation_curve_boundary_01.cc b/tests/opencascade/interpolation_curve_boundary_01.cc
index 8499e2b65f..8357b07b0d 100644
--- a/tests/opencascade/interpolation_curve_boundary_01.cc
+++ b/tests/opencascade/interpolation_curve_boundary_01.cc
@@ -51,7 +51,7 @@ template <int spacedim>
 void
 test()
 {
-  deallog << "Testing <2," << spacedim << ">" << std::endl;
+  deallog << "Testing <2," << spacedim << '>' << std::endl;
 
   Triangulation<2, spacedim> tria1;
   Triangulation<2, spacedim> tria2;
diff --git a/tests/opencascade/normal_to_mesh_projection_04.cc b/tests/opencascade/normal_to_mesh_projection_04.cc
index b8100e95e5..3d20443165 100644
--- a/tests/opencascade/normal_to_mesh_projection_04.cc
+++ b/tests/opencascade/normal_to_mesh_projection_04.cc
@@ -92,10 +92,9 @@ main()
 
   for (unsigned int i = 0; i < surrounding_points.size(); ++i)
     {
-      deallog << "Surrunding point " << i << " " << surrounding_points[i]
+      deallog << "Surrunding point " << i << ' ' << surrounding_points[i]
               << " weight " << weights[i] << std::endl;
     }
   deallog << "Mean point " << new_point_flat << std::endl;
-  deallog << "Projected point "
-          << " " << new_point << std::endl;
+  deallog << "Projected point " << ' ' << new_point << std::endl;
 }
diff --git a/tests/optimization/bfgs_03.cc b/tests/optimization/bfgs_03.cc
index 7cfa8ec81f..3cd41c86d0 100644
--- a/tests/optimization/bfgs_03.cc
+++ b/tests/optimization/bfgs_03.cc
@@ -102,7 +102,7 @@ test()
   const auto line_min =
     [&](number &f, VectorType &x, VectorType &g, const VectorType &p) {
       deallog << "-------------------" << std::endl
-              << "Line search " << iteration++ << ":" << std::endl;
+              << "Line search " << iteration++ << ':' << std::endl;
 
       const number g_norm_sqr = g.norm_sqr();
 
diff --git a/tests/optimization/cubic_fit.cc b/tests/optimization/cubic_fit.cc
index d0672d3779..1c8d619967 100644
--- a/tests/optimization/cubic_fit.cc
+++ b/tests/optimization/cubic_fit.cc
@@ -46,9 +46,9 @@ test()
     const double g2   = g(x2);
     const double res  = *LineMinimization::cubic_fit(x1, f1, g1, x2, f2, g2);
     const double res2 = *LineMinimization::cubic_fit(x2, f2, g2, x1, f1, g1);
-    deallog << x1 << " " << x2 << std::endl
-            << f1 << " " << f2 << std::endl
-            << g1 << " " << g2 << std::endl
+    deallog << x1 << ' ' << x2 << std::endl
+            << f1 << ' ' << f2 << std::endl
+            << g1 << ' ' << g2 << std::endl
             << res << std::endl
             << res2 << std::endl;
   }
diff --git a/tests/optimization/cubic_fit_three_points.cc b/tests/optimization/cubic_fit_three_points.cc
index 588944e3bf..9fbcb3e7f6 100644
--- a/tests/optimization/cubic_fit_three_points.cc
+++ b/tests/optimization/cubic_fit_three_points.cc
@@ -47,9 +47,9 @@ test()
     const double g1 = g(x1);
     const double res =
       *LineMinimization::cubic_fit_three_points(x1, f1, g1, x2, f2, x3, f3);
-    deallog << x1 << " " << f1 << " " << g1 << std::endl
-            << x2 << " " << f2 << std::endl
-            << x3 << " " << f3 << std::endl
+    deallog << x1 << ' ' << f1 << ' ' << g1 << std::endl
+            << x2 << ' ' << f2 << std::endl
+            << x3 << ' ' << f3 << std::endl
             << res << std::endl;
   }
 }
diff --git a/tests/optimization/line_minimization_03.cc b/tests/optimization/line_minimization_03.cc
index c328ef887a..66adcebe57 100644
--- a/tests/optimization/line_minimization_03.cc
+++ b/tests/optimization/line_minimization_03.cc
@@ -105,7 +105,7 @@ test()
           0.001);
 
         const auto fgi = func(res.first);
-        deallog << res.second << " " << res.first << " " << fgi.second
+        deallog << res.second << ' ' << res.first << ' ' << fgi.second
                 << std::endl;
       }
   }
@@ -133,7 +133,7 @@ test()
           0.1);
 
         const auto fgi = func(res.first);
-        deallog << res.second << " " << res.first << " " << fgi.second
+        deallog << res.second << ' ' << res.first << ' ' << fgi.second
                 << std::endl;
       }
   }
@@ -145,7 +145,7 @@ test()
     unsigned int ind = 4;
     for (auto p : params)
       {
-        deallog << "Table " << ind++ << ":" << std::endl;
+        deallog << "Table " << ind++ << ':' << std::endl;
         const double b1 = p.first;
         const double b2 = p.second;
 
@@ -175,7 +175,7 @@ test()
               0.001);
 
             const auto fgi = func(res.first);
-            deallog << res.second << " " << res.first << " " << fgi.second
+            deallog << res.second << ' ' << res.first << ' ' << fgi.second
                     << std::endl;
           }
       }
diff --git a/tests/optimization/line_minimization_03b.cc b/tests/optimization/line_minimization_03b.cc
index 42eb686cdf..ed50a0473f 100644
--- a/tests/optimization/line_minimization_03b.cc
+++ b/tests/optimization/line_minimization_03b.cc
@@ -103,7 +103,7 @@ test()
           0.001);
 
         const auto fgi = func(res.first);
-        deallog << res.second << " " << res.first << " " << fgi.second
+        deallog << res.second << ' ' << res.first << ' ' << fgi.second
                 << std::endl;
       }
   }
@@ -131,7 +131,7 @@ test()
           0.1);
 
         const auto fgi = func(res.first);
-        deallog << res.second << " " << res.first << " " << fgi.second
+        deallog << res.second << ' ' << res.first << ' ' << fgi.second
                 << std::endl;
       }
   }
@@ -143,7 +143,7 @@ test()
     unsigned int ind = 4;
     for (auto p : params)
       {
-        deallog << "Table " << ind++ << ":" << std::endl;
+        deallog << "Table " << ind++ << ':' << std::endl;
         const double b1 = p.first;
         const double b2 = p.second;
 
@@ -173,7 +173,7 @@ test()
               0.001);
 
             const auto fgi = func(res.first);
-            deallog << res.second << " " << res.first << " " << fgi.second
+            deallog << res.second << ' ' << res.first << ' ' << fgi.second
                     << std::endl;
           }
       }
diff --git a/tests/optimization/quadratic_fit.cc b/tests/optimization/quadratic_fit.cc
index dcf67266da..3ce1061b18 100644
--- a/tests/optimization/quadratic_fit.cc
+++ b/tests/optimization/quadratic_fit.cc
@@ -44,9 +44,9 @@ test()
     const double g1  = g(x1);
     const double g2  = g(x2);
     const double res = *LineMinimization::quadratic_fit(x1, f1, g1, x2, f2);
-    deallog << x1 << " " << x2 << std::endl
-            << f1 << " " << f2 << std::endl
-            << g1 << " " << g2 << std::endl
+    deallog << x1 << ' ' << x2 << std::endl
+            << f1 << ' ' << f2 << std::endl
+            << g1 << ' ' << g2 << std::endl
             << res << std::endl;
   }
 }
diff --git a/tests/parameter_handler/parameter_handler_20.cc b/tests/parameter_handler/parameter_handler_20.cc
index 4381f9758e..fe4bacfdb7 100644
--- a/tests/parameter_handler/parameter_handler_20.cc
+++ b/tests/parameter_handler/parameter_handler_20.cc
@@ -39,7 +39,7 @@ check(const char *content)
       foo.parse_input(ss);
       deallog << "input: ";
       foo.enter_subsection("bar");
-      deallog << foo.get_double("val") << " ";
+      deallog << foo.get_double("val") << ' ';
       foo.leave_subsection();
       deallog << foo.get_double("val2") << std::endl;
     }
diff --git a/tests/parameter_handler/patterns_07.cc b/tests/parameter_handler/patterns_07.cc
index 3c686f6aec..cc596a746e 100644
--- a/tests/parameter_handler/patterns_07.cc
+++ b/tests/parameter_handler/patterns_07.cc
@@ -51,7 +51,7 @@ main()
           << std::endl;
 
   for (auto i : a)
-    deallog << i.first << ":" << i.second << std::endl;
+    deallog << i.first << ':' << i.second << std::endl;
 
   return 0;
 }
diff --git a/tests/particles/lost_01.cc b/tests/particles/lost_01.cc
index 09d17b0c06..19fee88411 100644
--- a/tests/particles/lost_01.cc
+++ b/tests/particles/lost_01.cc
@@ -45,7 +45,7 @@ main()
 
   particle_handler.signals.particle_lost.connect(
     [](const auto &particle, const auto &cell) {
-      deallog << particle->get_id() << " " << cell->id() << std::endl;
+      deallog << particle->get_id() << ' ' << cell->id() << std::endl;
     });
 
   particle_handler.begin()->set_location(Point<dim>{2.0, 2.0});
diff --git a/tests/particles/particle_09.cc b/tests/particles/particle_09.cc
index e56d300176..9cb53e434b 100644
--- a/tests/particles/particle_09.cc
+++ b/tests/particles/particle_09.cc
@@ -43,7 +43,7 @@ test()
   auto p = random_point<spacedim>();
   for (const auto part : tree | bgi::adaptors::queried(bgi::nearest(p, 3)))
     deallog << "Particle " << part.get_id() << " is close to " << p
-            << " (location = " << part.get_location() << ")" << std::endl;
+            << " (location = " << part.get_location() << ')' << std::endl;
 }
 
 int
diff --git a/tests/particles/particle_handler_serial_08.cc b/tests/particles/particle_handler_serial_08.cc
index 4aede425f0..ac1ba1e62f 100644
--- a/tests/particles/particle_handler_serial_08.cc
+++ b/tests/particles/particle_handler_serial_08.cc
@@ -51,7 +51,7 @@ test()
   auto p = random_point<spacedim>();
   for (const auto &part : tree | bgi::adaptors::queried(bgi::nearest(p, 3)))
     deallog << "Particle " << part.get_id() << " is close to " << p
-            << " (location = " << part.get_location() << ")" << std::endl;
+            << " (location = " << part.get_location() << ')' << std::endl;
 }
 
 int
diff --git a/tests/particles/properties_01.cc b/tests/particles/properties_01.cc
index 3d73f7b70c..c5db16c1cf 100644
--- a/tests/particles/properties_01.cc
+++ b/tests/particles/properties_01.cc
@@ -107,13 +107,13 @@ test()
       for (unsigned int i = 0; i < ncomponents; ++i)
         {
           deallog << interpolatedParticleQuantities[part * ncomponents + i]
-                  << " ";
+                  << ' ';
         }
       deallog << std::endl;
       deallog << "expected quantities: ";
       for (unsigned int i = 0; i < dim; ++i)
         {
-          deallog << iter->get_location()[i] << " ";
+          deallog << iter->get_location()[i] << ' ';
         }
       deallog << " 1" << std::endl;
       deallog << std::endl;
diff --git a/tests/particles/properties_02.cc b/tests/particles/properties_02.cc
index 6eaea83539..80857e7a2d 100644
--- a/tests/particles/properties_02.cc
+++ b/tests/particles/properties_02.cc
@@ -111,13 +111,13 @@ test()
       for (unsigned int i = 0; i < ncomponents; ++i)
         {
           deallog << interpolatedParticleQuantities[part * ncomponents + i]
-                  << " ";
+                  << ' ';
         }
       deallog << std::endl;
       deallog << "expected quantities: ";
       for (unsigned int i = 0; i < dim; ++i)
         {
-          deallog << iter->get_location()[i] << " ";
+          deallog << iter->get_location()[i] << ' ';
         }
       deallog << " 1" << std::endl;
       deallog << std::endl;
diff --git a/tests/particles/property_pool_02.cc b/tests/particles/property_pool_02.cc
index 04ab17c933..a930bb849d 100644
--- a/tests/particles/property_pool_02.cc
+++ b/tests/particles/property_pool_02.cc
@@ -46,7 +46,7 @@ test()
     deallog << "Pool properties:";
 
     for (unsigned int i = 0; i < pool.get_properties(handle).size(); ++i)
-      deallog << " " << pool.get_properties(handle)[i];
+      deallog << ' ' << pool.get_properties(handle)[i];
 
     deallog << std::endl;
 
diff --git a/tests/particles/step-19.cc b/tests/particles/step-19.cc
index 124f681be1..12ee98c62b 100644
--- a/tests/particles/step-19.cc
+++ b/tests/particles/step-19.cc
@@ -1056,7 +1056,7 @@ namespace Step19
         for (const auto &particle : particle_handler)
           {
             deallog << "Particle " << particle.get_id() << ", at "
-                    << particle.get_location() << "/"
+                    << particle.get_location() << '/'
                     << particle.get_reference_location() << " with properties ";
             for (const auto x : particle.get_properties())
               deallog << x << ' ';
diff --git a/tests/particles/step-68.cc b/tests/particles/step-68.cc
index dc05749e2e..e4d6bbd440 100644
--- a/tests/particles/step-68.cc
+++ b/tests/particles/step-68.cc
@@ -570,7 +570,7 @@ namespace Step68
                                   "analytical-particles");
 
     if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
-      deallog << "Writing particle output file: " << file_name << "-" << it
+      deallog << "Writing particle output file: " << file_name << '-' << it
               << std::endl;
 
     particle_output.write_vtu_with_pvtu_record(
@@ -607,7 +607,7 @@ namespace Step68
     const std::string file_name("background");
 
     if (Utilities::MPI::this_mpi_process(mpi_communicator) == 0)
-      deallog << "Writing background field file: " << file_name << "-" << it
+      deallog << "Writing background field file: " << file_name << '-' << it
               << std::endl;
 
     data_out.write_vtu_with_pvtu_record(
diff --git a/tests/petsc/copy_to_dealvec_block.cc b/tests/petsc/copy_to_dealvec_block.cc
index fc20188a1b..f9f25eba1d 100644
--- a/tests/petsc/copy_to_dealvec_block.cc
+++ b/tests/petsc/copy_to_dealvec_block.cc
@@ -84,8 +84,8 @@ test()
   // check local values
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
     {
-      deallog << myid * 2 << ":" << copied(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << copied(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << copied(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << copied(myid * 2 + 1) << std::endl;
     }
 
   for (unsigned int bl = 0; bl < 2; ++bl)
@@ -106,8 +106,8 @@ test()
   // check local values
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
     {
-      deallog << myid * 2 << ":" << copied(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << copied(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << copied(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << copied(myid * 2 + 1) << std::endl;
     }
 
   for (unsigned int bl = 0; bl < 2; ++bl)
diff --git a/tests/petsc/full_matrix_00.cc b/tests/petsc/full_matrix_00.cc
index 999a94bf81..3903d62e46 100644
--- a/tests/petsc/full_matrix_00.cc
+++ b/tests/petsc/full_matrix_00.cc
@@ -47,7 +47,7 @@ test(PETScWrappers::FullMatrix &m)
   for (unsigned int i = 0; i < m.m(); ++i)
     {
       for (unsigned int j = 0; j < m.n(); ++j)
-        deallog << m(i, j) << " ";
+        deallog << m(i, j) << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
@@ -70,7 +70,7 @@ test(PETScWrappers::FullMatrix &m)
   for (unsigned int i = 0; i < m.m(); ++i)
     {
       for (unsigned int j = 0; j < m.n(); ++j)
-        deallog << m(i, j) << " ";
+        deallog << m(i, j) << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/petsc/sparse_matrix_01.cc b/tests/petsc/sparse_matrix_01.cc
index 32fa0ae71e..add619dc7f 100644
--- a/tests/petsc/sparse_matrix_01.cc
+++ b/tests/petsc/sparse_matrix_01.cc
@@ -48,21 +48,21 @@ test()
 
   deallog << "before: " << m(0, 1) << std::endl;
   for (unsigned int i = 0; i < s; ++i)
-    deallog << m(i, i) << " ";
+    deallog << m(i, i) << ' ';
   deallog << std::endl;
 
   m.add(1.0, m2);
 
   deallog << "after: " << m(0, 1) << std::endl;
   for (unsigned int i = 0; i < s; ++i)
-    deallog << m(i, i) << " ";
+    deallog << m(i, i) << ' ';
   deallog << std::endl;
 
   m.add(-1.0, m2);
 
   deallog << "back to original: " << m(0, 1) << std::endl;
   for (unsigned int i = 0; i < s; ++i)
-    deallog << m(i, i) << " ";
+    deallog << m(i, i) << ' ';
   deallog << std::endl;
 
   deallog << "OK" << std::endl;
diff --git a/tests/petsc/sparse_matrix_02.cc b/tests/petsc/sparse_matrix_02.cc
index dbfce83d2f..81a30b278d 100644
--- a/tests/petsc/sparse_matrix_02.cc
+++ b/tests/petsc/sparse_matrix_02.cc
@@ -43,7 +43,7 @@ test()
     Mat mm  = m;
     Mat m2m = m2;
 
-    // deallog << mm << " " << m2m << std::endl;
+    // deallog << mm << ' ' << m2m << std::endl;
 
     // forbidden:  m2 = m;
     {
@@ -51,7 +51,7 @@ test()
 
       Mat mm  = m;
       Mat m2m = m2;
-      // deallog << mm << " " << m2m << std::endl;
+      // deallog << mm << ' ' << m2m << std::endl;
     }
   }
 }
diff --git a/tests/petsc/sparse_matrix_03.cc b/tests/petsc/sparse_matrix_03.cc
index 76fb0f4e93..869af47474 100644
--- a/tests/petsc/sparse_matrix_03.cc
+++ b/tests/petsc/sparse_matrix_03.cc
@@ -35,7 +35,7 @@ test()
     for (unsigned int i = 0; i < m.m(); ++i)
       {
         for (unsigned int j = 0; j < m.n(); ++j)
-          deallog << m(i, j) << " ";
+          deallog << m(i, j) << ' ';
         deallog << std::endl;
       }
   };
diff --git a/tests/petsc_complex/sparse_matrix_01.cc b/tests/petsc_complex/sparse_matrix_01.cc
index 726ea2af6f..c273fa385e 100644
--- a/tests/petsc_complex/sparse_matrix_01.cc
+++ b/tests/petsc_complex/sparse_matrix_01.cc
@@ -47,21 +47,21 @@ test()
 
   deallog << "before: " << m(0, 1) << std::endl;
   for (unsigned int k = 0; k < s; ++k)
-    deallog << m(k, k) << " ";
+    deallog << m(k, k) << ' ';
   deallog << std::endl;
 
   m.add(m2, 1.0);
 
   deallog << "after: " << m(0, 1) << std::endl;
   for (unsigned int k = 0; k < s; ++k)
-    deallog << m(k, k) << " ";
+    deallog << m(k, k) << ' ';
   deallog << std::endl;
 
   m.add(m2, -1.0);
 
   deallog << "back to original: " << m(0, 1) << std::endl;
   for (unsigned int k = 0; k < s; ++k)
-    deallog << m(k, k) << " ";
+    deallog << m(k, k) << ' ';
   deallog << std::endl;
 
   deallog << "OK" << std::endl;
diff --git a/tests/petsc_complex/vector_02.cc b/tests/petsc_complex/vector_02.cc
index 2d75d1599f..752bf2d693 100644
--- a/tests/petsc_complex/vector_02.cc
+++ b/tests/petsc_complex/vector_02.cc
@@ -48,21 +48,21 @@ test()
 
   deallog << "before: " << std::endl;
   for (unsigned int k = 0; k < s; ++k)
-    deallog << "(" << v(k).real() << "," << v(k).imag() << "i) ";
+    deallog << '(' << v(k).real() << ',' << v(k).imag() << "i) ";
   deallog << std::endl;
 
   v.add(1.0, v2);
 
   deallog << "after: " << std::endl;
   for (unsigned int k = 0; k < s; ++k)
-    deallog << "(" << v(k).real() << "," << v(k).imag() << "i) ";
+    deallog << '(' << v(k).real() << ',' << v(k).imag() << "i) ";
   deallog << std::endl;
 
   v.add(-1.0, v2);
 
   deallog << "back to original: " << std::endl;
   for (unsigned int k = 0; k < s; ++k)
-    deallog << "(" << v(k).real() << "," << v(k).imag() << "i) ";
+    deallog << '(' << v(k).real() << ',' << v(k).imag() << "i) ";
   deallog << std::endl;
 
   deallog << "OK" << std::endl;
diff --git a/tests/physics/step-18-rotation_matrix.cc b/tests/physics/step-18-rotation_matrix.cc
index 0e14c7ca95..cc4e0bca19 100644
--- a/tests/physics/step-18-rotation_matrix.cc
+++ b/tests/physics/step-18-rotation_matrix.cc
@@ -594,7 +594,7 @@ namespace Step18
           pcout << (p == 0 ? ' ' : '+')
                 << (GridTools::count_cells_with_subdomain_association(
                      triangulation, p));
-        pcout << ")" << std::endl;
+        pcout << ')' << std::endl;
         setup_system();
         pcout << "    Number of degrees of freedom: " << dof_handler.n_dofs()
               << " (by partition:";
@@ -602,7 +602,7 @@ namespace Step18
           pcout << (p == 0 ? ' ' : '+')
                 << (DoFTools::count_dofs_with_subdomain_association(dof_handler,
                                                                     p));
-        pcout << ")" << std::endl;
+        pcout << ')' << std::endl;
         // Get point at which to output displacement
         // (outer radius of displaced surface)
         {
diff --git a/tests/physics/step-18.cc b/tests/physics/step-18.cc
index 91a73b5570..e94cd2f25c 100644
--- a/tests/physics/step-18.cc
+++ b/tests/physics/step-18.cc
@@ -610,7 +610,7 @@ namespace Step18
           pcout << (p == 0 ? ' ' : '+')
                 << (GridTools::count_cells_with_subdomain_association(
                      triangulation, p));
-        pcout << ")" << std::endl;
+        pcout << ')' << std::endl;
         setup_system();
         pcout << "    Number of degrees of freedom: " << dof_handler.n_dofs()
               << " (by partition:";
@@ -618,7 +618,7 @@ namespace Step18
           pcout << (p == 0 ? ' ' : '+')
                 << (DoFTools::count_dofs_with_subdomain_association(dof_handler,
                                                                     p));
-        pcout << ")" << std::endl;
+        pcout << ')' << std::endl;
         // Get point at which to output displacement
         // (outer radius of displaced surface)
         {
diff --git a/tests/physics/step-44-standard_tensors-material_push_forward.cc b/tests/physics/step-44-standard_tensors-material_push_forward.cc
index e265d6f99c..fe16b083ac 100644
--- a/tests/physics/step-44-standard_tensors-material_push_forward.cc
+++ b/tests/physics/step-44-standard_tensors-material_push_forward.cc
@@ -1438,7 +1438,7 @@ namespace Step44
   {
     pcout << std::endl
           << "Timestep " << time.get_timestep() << " @ " << time.current()
-          << "s" << std::endl;
+          << 's' << std::endl;
     BlockVector<double> newton_update(dofs_per_block);
     error_residual.reset();
     error_residual_0.reset();
@@ -1450,7 +1450,7 @@ namespace Step44
     unsigned int newton_iteration = 0;
     for (; newton_iteration < parameters.max_iterations_NR; ++newton_iteration)
       {
-        pcout << " " << std::setw(2) << newton_iteration << " " << std::flush;
+        pcout << ' ' << std::setw(2) << newton_iteration << ' ' << std::flush;
         tangent_matrix = 0.0;
         system_rhs     = 0.0;
         assemble_system_rhs();
@@ -1495,14 +1495,14 @@ namespace Step44
   {
     static const unsigned int l_width = 155;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
     pcout << "                 SOLVER STEP                  "
           << " |  LIN_IT   LIN_RES    RES_NORM    "
           << " RES_U     RES_P      RES_J     NU_NORM     "
           << " NU_U       NU_P       NU_J " << std::endl;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
   }
   template <int dim>
@@ -1511,7 +1511,7 @@ namespace Step44
   {
     static const unsigned int l_width = 155;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
     const std::pair<double, double> error_dil = get_error_dilation();
     pcout << "Relative errors:" << std::endl
diff --git a/tests/physics/step-44-standard_tensors-spatial.cc b/tests/physics/step-44-standard_tensors-spatial.cc
index f6b888eeaf..72f7f83b10 100644
--- a/tests/physics/step-44-standard_tensors-spatial.cc
+++ b/tests/physics/step-44-standard_tensors-spatial.cc
@@ -1238,7 +1238,7 @@ namespace Step44
   {
     pcout << std::endl
           << "Timestep " << time.get_timestep() << " @ " << time.current()
-          << "s" << std::endl;
+          << 's' << std::endl;
     BlockVector<double> newton_update(dofs_per_block);
     error_residual.reset();
     error_residual_0.reset();
@@ -1250,7 +1250,7 @@ namespace Step44
     unsigned int newton_iteration = 0;
     for (; newton_iteration < parameters.max_iterations_NR; ++newton_iteration)
       {
-        pcout << " " << std::setw(2) << newton_iteration << " " << std::flush;
+        pcout << ' ' << std::setw(2) << newton_iteration << ' ' << std::flush;
         tangent_matrix = 0.0;
         system_rhs     = 0.0;
         assemble_system_rhs();
@@ -1295,14 +1295,14 @@ namespace Step44
   {
     static const unsigned int l_width = 155;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
     pcout << "                 SOLVER STEP                  "
           << " |  LIN_IT   LIN_RES    RES_NORM    "
           << " RES_U     RES_P      RES_J     NU_NORM     "
           << " NU_U       NU_P       NU_J " << std::endl;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
   }
   template <int dim>
@@ -1311,7 +1311,7 @@ namespace Step44
   {
     static const unsigned int l_width = 155;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
     const std::pair<double, double> error_dil = get_error_dilation();
     pcout << "Relative errors:" << std::endl
diff --git a/tests/physics/step-44.cc b/tests/physics/step-44.cc
index c7a0f40978..3df381bfcd 100644
--- a/tests/physics/step-44.cc
+++ b/tests/physics/step-44.cc
@@ -1251,7 +1251,7 @@ namespace Step44
   {
     pcout << std::endl
           << "Timestep " << time.get_timestep() << " @ " << time.current()
-          << "s" << std::endl;
+          << 's' << std::endl;
     BlockVector<double> newton_update(dofs_per_block);
     error_residual.reset();
     error_residual_0.reset();
@@ -1263,7 +1263,7 @@ namespace Step44
     unsigned int newton_iteration = 0;
     for (; newton_iteration < parameters.max_iterations_NR; ++newton_iteration)
       {
-        pcout << " " << std::setw(2) << newton_iteration << " " << std::flush;
+        pcout << ' ' << std::setw(2) << newton_iteration << ' ' << std::flush;
         tangent_matrix = 0.0;
         system_rhs     = 0.0;
         assemble_system_rhs();
@@ -1308,14 +1308,14 @@ namespace Step44
   {
     static const unsigned int l_width = 155;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
     pcout << "                 SOLVER STEP                  "
           << " |  LIN_IT   LIN_RES    RES_NORM    "
           << " RES_U     RES_P      RES_J     NU_NORM     "
           << " NU_U       NU_P       NU_J " << std::endl;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
   }
   template <int dim>
@@ -1324,7 +1324,7 @@ namespace Step44
   {
     static const unsigned int l_width = 155;
     for (unsigned int i = 0; i < l_width; ++i)
-      pcout << "_";
+      pcout << '_';
     pcout << std::endl;
     const std::pair<double, double> error_dil = get_error_dilation();
     pcout << "Relative errors:" << std::endl
diff --git a/tests/quick_tests/mpi.cc b/tests/quick_tests/mpi.cc
index 0eb9e5d984..43dd40d29d 100644
--- a/tests/quick_tests/mpi.cc
+++ b/tests/quick_tests/mpi.cc
@@ -32,7 +32,7 @@ main(int argc, char *argv[])
   MPI_Comm_rank(MPI_COMM_WORLD, &myrank);
   MPI_Comm_size(MPI_COMM_WORLD, &nproc);
 
-  std::cout << " Hi from " << myrank << "/" << nproc << std::endl;
+  std::cout << " Hi from " << myrank << '/' << nproc << std::endl;
 
   if (nproc != 2)
     {
diff --git a/tests/quick_tests/scalapack.cc b/tests/quick_tests/scalapack.cc
index 60d2eb1e58..38fec4a037 100644
--- a/tests/quick_tests/scalapack.cc
+++ b/tests/quick_tests/scalapack.cc
@@ -79,8 +79,8 @@ test(const unsigned int size, const unsigned int block_size)
   ScaLAPACKMatrix<NumberType> scalapack_matrix(
     size, grid, block_size, LAPACKSupport::Property::symmetric);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   create_spd(full_in);
 
diff --git a/tests/quick_tests/step.cc b/tests/quick_tests/step.cc
index 85ea03511c..a87a918e63 100644
--- a/tests/quick_tests/step.cc
+++ b/tests/quick_tests/step.cc
@@ -94,7 +94,7 @@ LaplaceProblem<dim>::LaplaceProblem(const unsigned int mapping_degree)
   , mapping(mapping_degree)
   , last_error(std::numeric_limits<double>::max())
 {
-  deallog << "Using mapping with degree " << mapping_degree << ":" << std::endl
+  deallog << "Using mapping with degree " << mapping_degree << ':' << std::endl
           << "============================" << std::endl;
 }
 
diff --git a/tests/remote_point_evaluation/mapping_01.cc b/tests/remote_point_evaluation/mapping_01.cc
index 3246f9a61d..0a96a60ae7 100644
--- a/tests/remote_point_evaluation/mapping_01.cc
+++ b/tests/remote_point_evaluation/mapping_01.cc
@@ -77,8 +77,8 @@ test(const bool enforce_unique_map)
     eval, dof_handler, vec, VectorTools::EvaluationFlags::insert);
 
   for (unsigned int i = 0; i < evaluation_points.size(); ++i)
-    deallog << i << " " << result_avg[i] << " " << result_min[i] << " "
-            << result_max[i] << " " << result_insert[i] << " "
+    deallog << i << ' ' << result_avg[i] << ' ' << result_min[i] << ' '
+            << result_max[i] << ' ' << result_insert[i] << ' '
             << eval.get_point_ptrs()[i + 1] - eval.get_point_ptrs()[i]
             << std::endl;
 }
diff --git a/tests/remote_point_evaluation/mapping_02.cc b/tests/remote_point_evaluation/mapping_02.cc
index 38ea4889a6..df0db0e264 100644
--- a/tests/remote_point_evaluation/mapping_02.cc
+++ b/tests/remote_point_evaluation/mapping_02.cc
@@ -92,7 +92,7 @@ test()
   const auto expected_global_count =
     Utilities::MPI::sum(local_points.size(), MPI_COMM_WORLD);
 
-  deallog << global_count << " " << expected_global_count << std::endl;
+  deallog << global_count << ' ' << expected_global_count << std::endl;
 }
 
 
diff --git a/tests/remote_point_evaluation/mapping_03.cc b/tests/remote_point_evaluation/mapping_03.cc
index 3c5baeae2d..ef3bdfdac4 100644
--- a/tests/remote_point_evaluation/mapping_03.cc
+++ b/tests/remote_point_evaluation/mapping_03.cc
@@ -74,8 +74,8 @@ test(const bool enforce_unique_map)
     eval, dof_handler, vec, VectorTools::EvaluationFlags::insert);
 
   for (unsigned int i = 0; i < evaluation_points.size(); ++i)
-    deallog << "1e-" << (i + 1) << " " << result_avg[i] << " " << result_min[i]
-            << " " << result_max[i] << " " << result_insert[i] << " "
+    deallog << "1e-" << (i + 1) << ' ' << result_avg[i] << ' ' << result_min[i]
+            << ' ' << result_max[i] << ' ' << result_insert[i] << ' '
             << eval.get_point_ptrs()[i + 1] - eval.get_point_ptrs()[i]
             << std::endl;
 }
diff --git a/tests/remote_point_evaluation/remote_point_evaluation_01.cc b/tests/remote_point_evaluation/remote_point_evaluation_01.cc
index b27967cf6d..3baf49788e 100644
--- a/tests/remote_point_evaluation/remote_point_evaluation_01.cc
+++ b/tests/remote_point_evaluation/remote_point_evaluation_01.cc
@@ -237,7 +237,7 @@ print(std::tuple<
     {
       const unsigned int n_points = std::get<1>(result)[i].size();
 
-      std::cout << std::get<0>(result)[i]->level() << " "
+      std::cout << std::get<0>(result)[i]->level() << ' '
                 << std::get<0>(result)[i]->index() << " x " << n_points
                 << std::endl;
 
diff --git a/tests/remote_point_evaluation/remote_point_evaluation_03.cc b/tests/remote_point_evaluation/remote_point_evaluation_03.cc
index 726449f1ab..be497f3a55 100644
--- a/tests/remote_point_evaluation/remote_point_evaluation_03.cc
+++ b/tests/remote_point_evaluation/remote_point_evaluation_03.cc
@@ -260,7 +260,7 @@ test_1(const Triangulation<dim, spacedim> &surface_mesh,
           {
             if (JxW[q].distance(Point<spacedim>(phi_normal.get_value(q))) >
                 1e-7)
-              std::cout << JxW[q] << " " << phi_normal.get_value(q)
+              std::cout << JxW[q] << ' ' << phi_normal.get_value(q)
                         << std::endl;
           }
       }
@@ -318,7 +318,7 @@ test_2(const Triangulation<dim, spacedim> &surface_mesh,
     {
       if (integration_points[i].distance(
             Point<spacedim>(evaluation_point_results[i])) > 1e-7)
-        std::cout << integration_points[i] << " " << evaluation_point_results[i]
+        std::cout << integration_points[i] << ' ' << evaluation_point_results[i]
                   << std::endl;
     }
 }
diff --git a/tests/rol/vector_adaptor_02.cc b/tests/rol/vector_adaptor_02.cc
index 942f278c11..cd107b7469 100644
--- a/tests/rol/vector_adaptor_02.cc
+++ b/tests/rol/vector_adaptor_02.cc
@@ -113,7 +113,7 @@ test(const double x, const double y)
 
   Teuchos::RCP<const VectorType> xg = x_rol.getVector();
   std::cout << "The solution to minimization problem is: ";
-  std::cout << (*xg)[0] << " " << (*xg)[1] << std::endl;
+  std::cout << (*xg)[0] << ' ' << (*xg)[1] << std::endl;
 }
 
 int
diff --git a/tests/scalapack/scalapack_01.cc b/tests/scalapack/scalapack_01.cc
index 2b5849abcb..9ab3f8d616 100644
--- a/tests/scalapack/scalapack_01.cc
+++ b/tests/scalapack/scalapack_01.cc
@@ -49,8 +49,8 @@ test(const unsigned int size, const unsigned int block_size)
       mpi_communicator, size, size, block_size, block_size);
   ScaLAPACKMatrix<NumberType> scalapack_matrix(size, grid, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   {
     unsigned int index = 0;
diff --git a/tests/scalapack/scalapack_02.cc b/tests/scalapack/scalapack_02.cc
index b255b025a2..65638e80a3 100644
--- a/tests/scalapack/scalapack_02.cc
+++ b/tests/scalapack/scalapack_02.cc
@@ -56,8 +56,8 @@ test(const unsigned int size,
   ScaLAPACKMatrix<NumberType> scalapack_matrix(
     size, grid, block_size, LAPACKSupport::Property::symmetric);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   create_spd(full_in);
 
diff --git a/tests/scalapack/scalapack_03.cc b/tests/scalapack/scalapack_03.cc
index 824f206b4d..46238b3457 100644
--- a/tests/scalapack/scalapack_03.cc
+++ b/tests/scalapack/scalapack_03.cc
@@ -62,8 +62,8 @@ test(const unsigned int size, const unsigned int block_size)
   ScaLAPACKMatrix<NumberType> scalapack_matrix(
     size, grid, block_size, LAPACKSupport::Property::symmetric);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   create_spd(full_in);
 
diff --git a/tests/scalapack/scalapack_03_b.cc b/tests/scalapack/scalapack_03_b.cc
index 488fc93e54..1d7269d83a 100644
--- a/tests/scalapack/scalapack_03_b.cc
+++ b/tests/scalapack/scalapack_03_b.cc
@@ -64,8 +64,8 @@ test(const unsigned int size, const unsigned int block_size)
   ScaLAPACKMatrix<NumberType> scalapack_matrix(
     size, grid, block_size, LAPACKSupport::Property::general);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   // add a skew-symmetric matrix to the s.p.d matrix
   // the positive definiteness is inherited from the symmetric part
diff --git a/tests/scalapack/scalapack_03_c.cc b/tests/scalapack/scalapack_03_c.cc
index 0ccc8a4663..a973042f29 100644
--- a/tests/scalapack/scalapack_03_c.cc
+++ b/tests/scalapack/scalapack_03_c.cc
@@ -55,8 +55,8 @@ test(const unsigned int size, const unsigned int block_size)
   ScaLAPACKMatrix<NumberType> scalapack_matrix(
     size, grid, block_size, LAPACKSupport::Property::lower_triangular);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   create_random_lt(full_in);
 
diff --git a/tests/scalapack/scalapack_04.cc b/tests/scalapack/scalapack_04.cc
index 12d84cc3ad..35e64121a2 100644
--- a/tests/scalapack/scalapack_04.cc
+++ b/tests/scalapack/scalapack_04.cc
@@ -56,8 +56,8 @@ test(const unsigned int size,
                                           block_size,
                                           LAPACKSupport::Property::symmetric);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   create_spd(full_A);
 
@@ -80,9 +80,9 @@ test(const unsigned int size,
     dealii::Utilities::MPI::sum(s_frobenius, mpi_communicator) /
     n_mpi_processes;
 
-  pcout << l1 << " " << s_l1 << " " << as_l1 << std::endl
-        << linfty << " " << s_linfty << " " << as_linfty << std::endl
-        << frobenius << " " << s_frobenius << " " << as_frobenius << std::endl;
+  pcout << l1 << ' ' << s_l1 << ' ' << as_l1 << std::endl
+        << linfty << ' ' << s_linfty << ' ' << as_linfty << std::endl
+        << frobenius << ' ' << s_frobenius << ' ' << as_frobenius << std::endl;
 
   AssertThrow(std::abs(l1 - as_l1) < tol * std::abs(l1),
               dealii::ExcInternalError());
diff --git a/tests/scalapack/scalapack_04_b.cc b/tests/scalapack/scalapack_04_b.cc
index 08b2783069..105ec42eaa 100644
--- a/tests/scalapack/scalapack_04_b.cc
+++ b/tests/scalapack/scalapack_04_b.cc
@@ -54,8 +54,8 @@ test(const unsigned int size,
   ScaLAPACKMatrix<NumberType> scalapack(
     size, size, grid, block_size, block_size, LAPACKSupport::Property::general);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   create_random(full);
   scalapack = full;
@@ -78,9 +78,9 @@ test(const unsigned int size,
     dealii::Utilities::MPI::sum(s_frobenius, mpi_communicator) /
     n_mpi_processes;
 
-  pcout << l1 << " " << s_l1 << " " << as_l1 << std::endl
-        << linfty << " " << s_linfty << " " << as_linfty << std::endl
-        << frobenius << " " << s_frobenius << " " << as_frobenius << std::endl;
+  pcout << l1 << ' ' << s_l1 << ' ' << as_l1 << std::endl
+        << linfty << ' ' << s_linfty << ' ' << as_linfty << std::endl
+        << frobenius << ' ' << s_frobenius << ' ' << as_frobenius << std::endl;
 
   AssertThrow(std::abs(l1 - as_l1) < tol * std::abs(l1),
               dealii::ExcInternalError());
diff --git a/tests/scalapack/scalapack_05.cc b/tests/scalapack/scalapack_05.cc
index 9056d9a9ba..8ef3ac793d 100644
--- a/tests/scalapack/scalapack_05.cc
+++ b/tests/scalapack/scalapack_05.cc
@@ -55,8 +55,8 @@ test(const unsigned int size, const unsigned int block_size)
                                           block_size,
                                           LAPACKSupport::Property::symmetric);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   create_spd(full_A);
   inv_A.invert(full_A);
@@ -72,7 +72,7 @@ test(const unsigned int size, const unsigned int block_size)
     scalapack_A.reciprocal_condition_number(scalapack_l1);
 
 
-  pcout << 1. / (l1 * inv_l1) << " " << rcond << std::endl;
+  pcout << 1. / (l1 * inv_l1) << ' ' << rcond << std::endl;
 }
 
 
diff --git a/tests/scalapack/scalapack_06.cc b/tests/scalapack/scalapack_06.cc
index e4df7ce581..616d3922ed 100644
--- a/tests/scalapack/scalapack_06.cc
+++ b/tests/scalapack/scalapack_06.cc
@@ -56,8 +56,8 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   const unsigned int n_eigenvalues     = size;
   const unsigned int max_n_eigenvalues = 5;
diff --git a/tests/scalapack/scalapack_06a.cc b/tests/scalapack/scalapack_06a.cc
index ae905f8275..b22ef5bd35 100644
--- a/tests/scalapack/scalapack_06a.cc
+++ b/tests/scalapack/scalapack_06a.cc
@@ -57,8 +57,8 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   const unsigned int n_eigenvalues     = size;
   const unsigned int max_n_eigenvalues = 5;
diff --git a/tests/scalapack/scalapack_06b.cc b/tests/scalapack/scalapack_06b.cc
index e18874384a..bc3e88bc4a 100644
--- a/tests/scalapack/scalapack_06b.cc
+++ b/tests/scalapack/scalapack_06b.cc
@@ -57,8 +57,8 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   const unsigned int n_eigenvalues     = size;
   const unsigned int max_n_eigenvalues = 5;
diff --git a/tests/scalapack/scalapack_06c.cc b/tests/scalapack/scalapack_06c.cc
index f0e31f9643..ad0e200a2c 100644
--- a/tests/scalapack/scalapack_06c.cc
+++ b/tests/scalapack/scalapack_06c.cc
@@ -57,8 +57,8 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   const unsigned int n_eigenvalues     = size;
   const unsigned int max_n_eigenvalues = 5;
diff --git a/tests/scalapack/scalapack_07.cc b/tests/scalapack/scalapack_07.cc
index 3f1529376d..5d25c39c2f 100644
--- a/tests/scalapack/scalapack_07.cc
+++ b/tests/scalapack/scalapack_07.cc
@@ -74,20 +74,20 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
   ScaLAPACKMatrix<NumberType> scalapack_matrix_source(
     size, size, grid_single, block_size_j, block_size_i);
 
-  pcout << "2D grid matrix: dim=" << scalapack_matrix_2d.m() << "x"
-        << scalapack_matrix_2d.n() << ";  blocks=" << block_size_i << "x"
-        << block_size_i << ";  grid=" << grid_2d->get_process_grid_rows() << "x"
+  pcout << "2D grid matrix: dim=" << scalapack_matrix_2d.m() << 'x'
+        << scalapack_matrix_2d.n() << ";  blocks=" << block_size_i << 'x'
+        << block_size_i << ";  grid=" << grid_2d->get_process_grid_rows() << 'x'
         << grid_2d->get_process_grid_columns() << std::endl;
 
-  pcout << "1D grid matrix: " << scalapack_matrix_1d.m() << "x"
-        << scalapack_matrix_1d.n() << ";  blocks=" << block_size_j << "x"
-        << block_size_j << ";  grid=" << grid_1d->get_process_grid_rows() << "x"
+  pcout << "1D grid matrix: " << scalapack_matrix_1d.m() << 'x'
+        << scalapack_matrix_1d.n() << ";  blocks=" << block_size_j << 'x'
+        << block_size_j << ";  grid=" << grid_1d->get_process_grid_rows() << 'x'
         << grid_1d->get_process_grid_columns() << std::endl;
 
-  pcout << "single process matrix: " << scalapack_matrix_single.m() << "x"
-        << scalapack_matrix_single.n() << ";  blocks=" << block_size_i << "x"
+  pcout << "single process matrix: " << scalapack_matrix_single.m() << 'x'
+        << scalapack_matrix_single.n() << ";  blocks=" << block_size_i << 'x'
         << block_size_j << ";  grid=" << grid_single->get_process_grid_rows()
-        << "x" << grid_single->get_process_grid_columns() << std::endl
+        << 'x' << grid_single->get_process_grid_columns() << std::endl
         << std::endl;
 
   scalapack_matrix_source = full;
diff --git a/tests/scalapack/scalapack_08.cc b/tests/scalapack/scalapack_08.cc
index 4e9a9af536..5a484caf9b 100644
--- a/tests/scalapack/scalapack_08.cc
+++ b/tests/scalapack/scalapack_08.cc
@@ -55,7 +55,7 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << std::endl;
+  pcout << size << ' ' << block_size << std::endl;
 
   // Create s.p.d matrices of requested size:
   FullMatrix<NumberType> full_A(size);
diff --git a/tests/scalapack/scalapack_10.cc b/tests/scalapack/scalapack_10.cc
index dd828c4e32..9e73d30311 100644
--- a/tests/scalapack/scalapack_10.cc
+++ b/tests/scalapack/scalapack_10.cc
@@ -68,7 +68,7 @@ test(const unsigned int size, const unsigned int block_size)
   scalapack_matrix_copy.copy_to(copy);
   copy.add(-1, full);
 
-  pcout << size << " " << block_size << std::endl;
+  pcout << size << ' ' << block_size << std::endl;
 
   if (copy.frobenius_norm() > 1e-12)
     pcout << "norm of difference: " << copy.frobenius_norm() << std::endl;
diff --git a/tests/scalapack/scalapack_10_a.cc b/tests/scalapack/scalapack_10_a.cc
index 444ca75178..ca9fb7ed75 100644
--- a/tests/scalapack/scalapack_10_a.cc
+++ b/tests/scalapack/scalapack_10_a.cc
@@ -88,7 +88,7 @@ test(const unsigned int size, const unsigned int block_size)
   copy_I.add(-1, full);
   copy_II.add(-1, full);
 
-  pcout << size << " " << block_size << std::endl;
+  pcout << size << ' ' << block_size << std::endl;
 
   if (copy_I.frobenius_norm() > 1e-12)
     pcout << "norm of difference I: " << copy_I.frobenius_norm() << std::endl;
diff --git a/tests/scalapack/scalapack_10_b.cc b/tests/scalapack/scalapack_10_b.cc
index 5b7edab75e..89bfb3ef9a 100644
--- a/tests/scalapack/scalapack_10_b.cc
+++ b/tests/scalapack/scalapack_10_b.cc
@@ -67,9 +67,9 @@ test(const std::pair<unsigned int, unsigned int> &size,
   scalapack_matrix_copy.copy_to(copy);
   copy.add(-1, full);
 
-  pcout << size.first << "x" << size.second << " & " << block_size << " & "
-        << chunk_size.first << "x" << chunk_size.second << " & "
-        << grid->get_process_grid_rows() << "x"
+  pcout << size.first << 'x' << size.second << " & " << block_size << " & "
+        << chunk_size.first << 'x' << chunk_size.second << " & "
+        << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl;
   AssertThrow(copy.frobenius_norm() < 1e-12, ExcInternalError());
   std::remove(filename.c_str());
diff --git a/tests/scalapack/scalapack_10_d.cc b/tests/scalapack/scalapack_10_d.cc
index ff1667a08a..dcc9da4dbf 100644
--- a/tests/scalapack/scalapack_10_d.cc
+++ b/tests/scalapack/scalapack_10_d.cc
@@ -74,7 +74,7 @@ test(const unsigned int size, const unsigned int block_size)
   scalapack_matrix.copy_to(copy);
   copy.add(-1, full);
 
-  pcout << size << " " << block_size << std::endl;
+  pcout << size << ' ' << block_size << std::endl;
 
   if (copy.frobenius_norm() > 1e-12)
     pcout << "norm of difference: " << copy.frobenius_norm() << std::endl;
diff --git a/tests/scalapack/scalapack_11.cc b/tests/scalapack/scalapack_11.cc
index 1d4b384212..4500ac0dfc 100644
--- a/tests/scalapack/scalapack_11.cc
+++ b/tests/scalapack/scalapack_11.cc
@@ -60,9 +60,9 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
   ScaLAPACKMatrix<NumberType> scalapack_matrix(
     size, size, grid, block_size_i, block_size_i);
 
-  pcout << "2D grid matrix: dim=" << scalapack_matrix.m() << "x"
-        << scalapack_matrix.n() << ";  blocks=" << block_size_i << "x"
-        << block_size_i << ";  grid=" << grid->get_process_grid_rows() << "x"
+  pcout << "2D grid matrix: dim=" << scalapack_matrix.m() << 'x'
+        << scalapack_matrix.n() << ";  blocks=" << block_size_i << 'x'
+        << block_size_i << ";  grid=" << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
diff --git a/tests/scalapack/scalapack_12_a.cc b/tests/scalapack/scalapack_12_a.cc
index f850258d44..a4a7ec8488 100644
--- a/tests/scalapack/scalapack_12_a.cc
+++ b/tests/scalapack/scalapack_12_a.cc
@@ -54,7 +54,7 @@ test()
     std::make_shared<Utilities::MPI::ProcessGrid>(mpi_communicator,
                                                   proc_rows,
                                                   proc_columns);
-  pcout << "2D process grid: " << grid->get_process_grid_rows() << "x"
+  pcout << "2D process grid: " << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
@@ -93,9 +93,9 @@ test()
   scalapack_C.copy_to(tmp_full_C);
 
   pcout << "   computing C = b A * B + c C with"
-        << " A in R^(" << scalapack_A.m() << "x" << scalapack_A.n() << "),"
-        << " B in R^(" << scalapack_B.m() << "x" << scalapack_B.n() << ") and"
-        << " C in R^(" << scalapack_C.m() << "x" << scalapack_C.n() << ")"
+        << " A in R^(" << scalapack_A.m() << 'x' << scalapack_A.n() << "),"
+        << " B in R^(" << scalapack_B.m() << 'x' << scalapack_B.n() << ") and"
+        << " C in R^(" << scalapack_C.m() << 'x' << scalapack_C.n() << ')'
         << std::endl;
   pcout << "   norms: " << tmp_full_C.frobenius_norm() << " & "
         << full_C.frobenius_norm() << "  for " << typeid(NumberType).name()
diff --git a/tests/scalapack/scalapack_12_b.cc b/tests/scalapack/scalapack_12_b.cc
index 815a169534..ee9eda74ff 100644
--- a/tests/scalapack/scalapack_12_b.cc
+++ b/tests/scalapack/scalapack_12_b.cc
@@ -55,7 +55,7 @@ test()
     std::make_shared<Utilities::MPI::ProcessGrid>(mpi_communicator,
                                                   proc_rows,
                                                   proc_columns);
-  pcout << "2D process grid: " << grid->get_process_grid_rows() << "x"
+  pcout << "2D process grid: " << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
@@ -94,9 +94,9 @@ test()
   scalapack_C.copy_to(tmp_full_C);
 
   pcout << "   computing C = b A^T * B + c C with"
-        << " A in R^(" << scalapack_A.m() << "x" << scalapack_A.n() << "),"
-        << " B in R^(" << scalapack_B.m() << "x" << scalapack_B.n() << ") and"
-        << " C in R^(" << scalapack_C.m() << "x" << scalapack_C.n() << ")"
+        << " A in R^(" << scalapack_A.m() << 'x' << scalapack_A.n() << "),"
+        << " B in R^(" << scalapack_B.m() << 'x' << scalapack_B.n() << ") and"
+        << " C in R^(" << scalapack_C.m() << 'x' << scalapack_C.n() << ')'
         << std::endl;
   pcout << "   norms: " << tmp_full_C.frobenius_norm() << " & "
         << full_C.frobenius_norm() << "  for " << typeid(NumberType).name()
diff --git a/tests/scalapack/scalapack_12_c.cc b/tests/scalapack/scalapack_12_c.cc
index b8c5d16007..1df6fa704c 100644
--- a/tests/scalapack/scalapack_12_c.cc
+++ b/tests/scalapack/scalapack_12_c.cc
@@ -55,7 +55,7 @@ test()
     std::make_shared<Utilities::MPI::ProcessGrid>(mpi_communicator,
                                                   proc_rows,
                                                   proc_columns);
-  pcout << "2D process grid: " << grid->get_process_grid_rows() << "x"
+  pcout << "2D process grid: " << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
@@ -94,9 +94,9 @@ test()
   scalapack_C.copy_to(tmp_full_C);
 
   pcout << "   computing C = b A * B^T + c C with"
-        << " A in R^(" << scalapack_A.m() << "x" << scalapack_A.n() << "),"
-        << " B in R^(" << scalapack_B.m() << "x" << scalapack_B.n() << ") and"
-        << " C in R^(" << scalapack_C.m() << "x" << scalapack_C.n() << ")"
+        << " A in R^(" << scalapack_A.m() << 'x' << scalapack_A.n() << "),"
+        << " B in R^(" << scalapack_B.m() << 'x' << scalapack_B.n() << ") and"
+        << " C in R^(" << scalapack_C.m() << 'x' << scalapack_C.n() << ')'
         << std::endl;
   pcout << "   norms: " << tmp_full_C.frobenius_norm() << " & "
         << full_C.frobenius_norm() << "  for " << typeid(NumberType).name()
diff --git a/tests/scalapack/scalapack_12_d.cc b/tests/scalapack/scalapack_12_d.cc
index be96d07ae8..4e0dff12df 100644
--- a/tests/scalapack/scalapack_12_d.cc
+++ b/tests/scalapack/scalapack_12_d.cc
@@ -55,7 +55,7 @@ test()
     std::make_shared<Utilities::MPI::ProcessGrid>(mpi_communicator,
                                                   proc_rows,
                                                   proc_columns);
-  pcout << "2D process grid: " << grid->get_process_grid_rows() << "x"
+  pcout << "2D process grid: " << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
@@ -94,9 +94,9 @@ test()
   scalapack_C.copy_to(tmp_full_C);
 
   pcout << "   computing C = b A^T * B^T + c C with"
-        << " A in R^(" << scalapack_A.m() << "x" << scalapack_A.n() << "),"
-        << " B in R^(" << scalapack_B.m() << "x" << scalapack_B.n() << ") and"
-        << " C in R^(" << scalapack_C.m() << "x" << scalapack_C.n() << ")"
+        << " A in R^(" << scalapack_A.m() << 'x' << scalapack_A.n() << "),"
+        << " B in R^(" << scalapack_B.m() << 'x' << scalapack_B.n() << ") and"
+        << " C in R^(" << scalapack_C.m() << 'x' << scalapack_C.n() << ')'
         << std::endl;
   pcout << "   norms: " << tmp_full_C.frobenius_norm() << " & "
         << full_C.frobenius_norm() << "  for " << typeid(NumberType).name()
diff --git a/tests/scalapack/scalapack_13_a.cc b/tests/scalapack/scalapack_13_a.cc
index df7d40c2be..0a15fd89e5 100644
--- a/tests/scalapack/scalapack_13_a.cc
+++ b/tests/scalapack/scalapack_13_a.cc
@@ -54,7 +54,7 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
     std::make_shared<Utilities::MPI::ProcessGrid>(mpi_communicator,
                                                   proc_rows,
                                                   proc_columns);
-  pcout << "2D process grid: " << grid->get_process_grid_rows() << "x"
+  pcout << "2D process grid: " << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
@@ -86,8 +86,8 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
   scalapack_A.copy_to(tmp_full_A);
 
   pcout << "   computing A = alpha A + beta B with"
-        << " A in R^(" << scalapack_A.m() << "x" << scalapack_A.n() << ") and"
-        << " B in R^(" << scalapack_B.m() << "x" << scalapack_B.n() << ")"
+        << " A in R^(" << scalapack_A.m() << 'x' << scalapack_A.n() << ") and"
+        << " B in R^(" << scalapack_B.m() << 'x' << scalapack_B.n() << ')'
         << std::endl;
   pcout << "   norms: " << tmp_full_A.frobenius_norm() << " & "
         << full_A.frobenius_norm() << "  for " << typeid(NumberType).name()
diff --git a/tests/scalapack/scalapack_13_b.cc b/tests/scalapack/scalapack_13_b.cc
index 07a39b8f8c..08a23aeaa8 100644
--- a/tests/scalapack/scalapack_13_b.cc
+++ b/tests/scalapack/scalapack_13_b.cc
@@ -54,7 +54,7 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
     std::make_shared<Utilities::MPI::ProcessGrid>(mpi_communicator,
                                                   proc_rows,
                                                   proc_columns);
-  pcout << "2D process grid: " << grid->get_process_grid_rows() << "x"
+  pcout << "2D process grid: " << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
@@ -88,8 +88,8 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
   scalapack_A.copy_to(tmp_full_A);
 
   pcout << "   computing A = alpha A + beta B^T with"
-        << " A in R^(" << scalapack_A.m() << "x" << scalapack_A.n() << ") and"
-        << " B in R^(" << scalapack_B.m() << "x" << scalapack_B.n() << ")"
+        << " A in R^(" << scalapack_A.m() << 'x' << scalapack_A.n() << ") and"
+        << " B in R^(" << scalapack_B.m() << 'x' << scalapack_B.n() << ')'
         << std::endl;
   pcout << "   norms: " << tmp_full_A.frobenius_norm() << " & "
         << full_A.frobenius_norm() << "  for " << typeid(NumberType).name()
diff --git a/tests/scalapack/scalapack_14_a.cc b/tests/scalapack/scalapack_14_a.cc
index 013859a1ee..74cba92456 100644
--- a/tests/scalapack/scalapack_14_a.cc
+++ b/tests/scalapack/scalapack_14_a.cc
@@ -55,7 +55,7 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
   std::shared_ptr<Utilities::MPI::ProcessGrid> grid =
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, sizes[0], sizes[1], block_size_i, block_size_i);
-  pcout << "2D process grid: " << grid->get_process_grid_rows() << "x"
+  pcout << "2D process grid: " << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
@@ -80,7 +80,7 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
       full_A(i, j) *= scaling_factors[i];
 
   pcout << "   Row scaling for"
-        << " A in R^(" << scalapack_A.m() << "x" << scalapack_A.n() << ")"
+        << " A in R^(" << scalapack_A.m() << 'x' << scalapack_A.n() << ')'
         << std::endl;
   pcout << "   norms: " << tmp_full_A.frobenius_norm() << " & "
         << full_A.frobenius_norm() << "  for " << typeid(NumberType).name()
diff --git a/tests/scalapack/scalapack_14_b.cc b/tests/scalapack/scalapack_14_b.cc
index 7e726303fa..ca17b01646 100644
--- a/tests/scalapack/scalapack_14_b.cc
+++ b/tests/scalapack/scalapack_14_b.cc
@@ -55,7 +55,7 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
   std::shared_ptr<Utilities::MPI::ProcessGrid> grid =
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, sizes[0], sizes[1], block_size_i, block_size_i);
-  pcout << "2D process grid: " << grid->get_process_grid_rows() << "x"
+  pcout << "2D process grid: " << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
@@ -80,7 +80,7 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
       full_A(i, j) *= scaling_factors[j];
 
   pcout << "   Column scaling for"
-        << " A in R^(" << scalapack_A.m() << "x" << scalapack_A.n() << ")"
+        << " A in R^(" << scalapack_A.m() << 'x' << scalapack_A.n() << ')'
         << std::endl;
   pcout << "   norms: " << tmp_full_A.frobenius_norm() << " & "
         << full_A.frobenius_norm() << "  for " << typeid(NumberType).name()
diff --git a/tests/scalapack/scalapack_15.cc b/tests/scalapack/scalapack_15.cc
index 1005e4515f..b88a7355d9 100644
--- a/tests/scalapack/scalapack_15.cc
+++ b/tests/scalapack/scalapack_15.cc
@@ -56,8 +56,8 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   const unsigned int n_eigenvalues     = size;
   const unsigned int max_n_eigenvalues = 5;
diff --git a/tests/scalapack/scalapack_15_a.cc b/tests/scalapack/scalapack_15_a.cc
index 57da9158f7..d5c107cae2 100644
--- a/tests/scalapack/scalapack_15_a.cc
+++ b/tests/scalapack/scalapack_15_a.cc
@@ -56,8 +56,8 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   const unsigned int n_eigenvalues     = size;
   const unsigned int max_n_eigenvalues = 5;
diff --git a/tests/scalapack/scalapack_16.cc b/tests/scalapack/scalapack_16.cc
index 1aa87d464d..7986f90512 100644
--- a/tests/scalapack/scalapack_16.cc
+++ b/tests/scalapack/scalapack_16.cc
@@ -54,8 +54,8 @@ test(const unsigned int size,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size, size, block_size, block_size);
 
-  pcout << size << " " << block_size << " " << grid->get_process_grid_rows()
-        << " " << grid->get_process_grid_columns() << std::endl;
+  pcout << size << ' ' << block_size << ' ' << grid->get_process_grid_rows()
+        << ' ' << grid->get_process_grid_columns() << std::endl;
 
   // Create SPD matrices of requested size:
   FullMatrix<NumberType> full_A(size), singular_A(size);
@@ -91,8 +91,8 @@ test(const unsigned int size,
 
   if (this_mpi_process == 0)
     {
-      std::cout << "ranks: " << rank_1 << "/" << size << "  &  ";
-      std::cout << rank_2 << "/" << size << std::endl;
+      std::cout << "ranks: " << rank_1 << '/' << size << "  &  ";
+      std::cout << rank_2 << '/' << size << std::endl;
       double norm = full_pseudo_inverse.frobenius_norm();
       full_inverse.add(-1, full_pseudo_inverse);
       norm = full_inverse.frobenius_norm() / norm;
diff --git a/tests/scalapack/scalapack_16_a.cc b/tests/scalapack/scalapack_16_a.cc
index b2a9ad073f..bfd0cdd453 100644
--- a/tests/scalapack/scalapack_16_a.cc
+++ b/tests/scalapack/scalapack_16_a.cc
@@ -55,8 +55,8 @@ test(const unsigned int size_1,
     std::make_shared<Utilities::MPI::ProcessGrid>(
       mpi_communicator, size_1, size_2, block_size, block_size);
 
-  pcout << size_1 << "x" << size_2 << " " << block_size << " "
-        << grid->get_process_grid_rows() << " "
+  pcout << size_1 << 'x' << size_2 << ' ' << block_size << ' '
+        << grid->get_process_grid_rows() << ' '
         << grid->get_process_grid_columns() << std::endl;
 
   // Create randomly filled matrix of requested dimension size_1xsize_2:
@@ -106,7 +106,7 @@ test(const unsigned int size_1,
 
   if (this_mpi_process == 0)
     {
-      std::cout << "rank=" << rank << "/" << std::min(size_1, size_2)
+      std::cout << "rank=" << rank << '/' << std::min(size_1, size_2)
                 << std::endl;
       AssertThrow(norm < tol, ExcInternalError());
     }
diff --git a/tests/scalapack/scalapack_17_a.cc b/tests/scalapack/scalapack_17_a.cc
index 03ed3afc1e..c60431f06a 100644
--- a/tests/scalapack/scalapack_17_a.cc
+++ b/tests/scalapack/scalapack_17_a.cc
@@ -54,9 +54,9 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
   ScaLAPACKMatrix<NumberType> scalapack_matrix(
     size, size, grid, block_size_i, block_size_i);
 
-  pcout << "2D grid matrix: dim=" << scalapack_matrix.m() << "x"
-        << scalapack_matrix.n() << ";  blocks=" << block_size_i << "x"
-        << block_size_i << ";  grid=" << grid->get_process_grid_rows() << "x"
+  pcout << "2D grid matrix: dim=" << scalapack_matrix.m() << 'x'
+        << scalapack_matrix.n() << ";  blocks=" << block_size_i << 'x'
+        << block_size_i << ";  grid=" << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
diff --git a/tests/scalapack/scalapack_17_b.cc b/tests/scalapack/scalapack_17_b.cc
index ed347d53d8..43b7fb486a 100644
--- a/tests/scalapack/scalapack_17_b.cc
+++ b/tests/scalapack/scalapack_17_b.cc
@@ -59,9 +59,9 @@ test(const unsigned int block_size_i, const unsigned int block_size_j)
   ScaLAPACKMatrix<NumberType> scalapack_matrix(
     size, size, grid, block_size_i, block_size_i);
 
-  pcout << "2D grid matrix: dim=" << scalapack_matrix.m() << "x"
-        << scalapack_matrix.n() << ";  blocks=" << block_size_i << "x"
-        << block_size_i << ";  grid=" << grid->get_process_grid_rows() << "x"
+  pcout << "2D grid matrix: dim=" << scalapack_matrix.m() << 'x'
+        << scalapack_matrix.n() << ";  blocks=" << block_size_i << 'x'
+        << block_size_i << ";  grid=" << grid->get_process_grid_rows() << 'x'
         << grid->get_process_grid_columns() << std::endl
         << std::endl;
 
diff --git a/tests/serialization/particle_01.cc b/tests/serialization/particle_01.cc
index 860b421609..5b0114f617 100644
--- a/tests/serialization/particle_01.cc
+++ b/tests/serialization/particle_01.cc
@@ -49,7 +49,7 @@ test()
     deallog << "Before serialization particle id " << particle.get_id()
             << " has location " << particle.get_location()
             << ", has reference location " << particle.get_reference_location()
-            << ", and has properties " << particle.get_properties()[0] << " "
+            << ", and has properties " << particle.get_properties()[0] << ' '
             << particle.get_properties()[1] << std::endl;
 
     boost::archive::text_oarchive oa(oss, boost::archive::no_header);
@@ -75,7 +75,7 @@ test()
     deallog << "After serialization particle id " << particle.get_id()
             << " has location " << particle.get_location()
             << ", has reference location " << particle.get_reference_location()
-            << ", and has properties " << particle.get_properties()[0] << " "
+            << ", and has properties " << particle.get_properties()[0] << ' '
             << particle.get_properties()[1] << std::endl;
   }
 
diff --git a/tests/sharedtria/dof_01.cc b/tests/sharedtria/dof_01.cc
index 0b198a48e3..9f57f4c57f 100644
--- a/tests/sharedtria/dof_01.cc
+++ b/tests/sharedtria/dof_01.cc
@@ -110,7 +110,7 @@ test()
       //      unsigned int sum = 0;
       //      for (unsigned int i=0; i<v.size(); ++i)
       //        {
-      //          deallog << v[i] << " ";
+      //          deallog << v[i] << ' ';
       //          sum += v[i];
       //        }
       //      deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/dof_02.cc b/tests/sharedtria/dof_02.cc
index 6da95d31ad..8ae5394a47 100644
--- a/tests/sharedtria/dof_02.cc
+++ b/tests/sharedtria/dof_02.cc
@@ -110,7 +110,7 @@ test()
       //      unsigned int sum = 0;
       //      for (unsigned int i=0; i<v.size(); ++i)
       //        {
-      //          deallog << v[i] << " ";
+      //          deallog << v[i] << ' ';
       //          sum += v[i];
       //        }
       //      deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/dof_03.cc b/tests/sharedtria/dof_03.cc
index 91dd8787a0..af32041950 100644
--- a/tests/sharedtria/dof_03.cc
+++ b/tests/sharedtria/dof_03.cc
@@ -108,7 +108,7 @@ test()
       //      unsigned int sum = 0;
       //      for (unsigned int i=0; i<v.size(); ++i)
       //        {
-      //          deallog << v[i] << " ";
+      //          deallog << v[i] << ' ';
       //          sum += v[i];
       //        }
       //      deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/dof_04.cc b/tests/sharedtria/dof_04.cc
index 8a6181e096..aa08376fa9 100644
--- a/tests/sharedtria/dof_04.cc
+++ b/tests/sharedtria/dof_04.cc
@@ -110,7 +110,7 @@ test()
       //      unsigned int sum = 0;
       //      for (unsigned int i=0; i<v.size(); ++i)
       //        {
-      //          deallog << v[i] << " ";
+      //          deallog << v[i] << ' ';
       //          sum += v[i];
       //        }
       //      deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/dof_06.cc b/tests/sharedtria/dof_06.cc
index d2a91af60b..c55b56ab86 100644
--- a/tests/sharedtria/dof_06.cc
+++ b/tests/sharedtria/dof_06.cc
@@ -91,7 +91,7 @@ test()
       cell->get_dof_indices(local_dof_indices);
       deallog << "cell" << cell->index() << " has dofs: ";
       for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-        deallog << local_dof_indices[i] << " ";
+        deallog << local_dof_indices[i] << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/sharedtria/hp_dof_01.cc b/tests/sharedtria/hp_dof_01.cc
index cce17f7cc7..95c5e7acae 100644
--- a/tests/sharedtria/hp_dof_01.cc
+++ b/tests/sharedtria/hp_dof_01.cc
@@ -115,7 +115,7 @@ test()
       //      unsigned int sum = 0;
       //      for (unsigned int i=0; i<v.size(); ++i)
       //        {
-      //          deallog << v[i] << " ";
+      //          deallog << v[i] << ' ';
       //          sum += v[i];
       //        }
       //      deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/hp_dof_02.cc b/tests/sharedtria/hp_dof_02.cc
index 71556df562..7fa47fc3d2 100644
--- a/tests/sharedtria/hp_dof_02.cc
+++ b/tests/sharedtria/hp_dof_02.cc
@@ -115,7 +115,7 @@ test()
       //      unsigned int sum = 0;
       //      for (unsigned int i=0; i<v.size(); ++i)
       //        {
-      //          deallog << v[i] << " ";
+      //          deallog << v[i] << ' ';
       //          sum += v[i];
       //        }
       //      deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/hp_dof_03.cc b/tests/sharedtria/hp_dof_03.cc
index 9d125dc13f..01bef9f7b5 100644
--- a/tests/sharedtria/hp_dof_03.cc
+++ b/tests/sharedtria/hp_dof_03.cc
@@ -113,7 +113,7 @@ test()
       //      unsigned int sum = 0;
       //      for (unsigned int i=0; i<v.size(); ++i)
       //        {
-      //          deallog << v[i] << " ";
+      //          deallog << v[i] << ' ';
       //          sum += v[i];
       //        }
       //      deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/hp_dof_04.cc b/tests/sharedtria/hp_dof_04.cc
index 5c92792d89..1b5367d088 100644
--- a/tests/sharedtria/hp_dof_04.cc
+++ b/tests/sharedtria/hp_dof_04.cc
@@ -115,7 +115,7 @@ test()
       //      unsigned int sum = 0;
       //      for (unsigned int i=0; i<v.size(); ++i)
       //        {
-      //          deallog << v[i] << " ";
+      //          deallog << v[i] << ' ';
       //          sum += v[i];
       //        }
       //      deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/hp_no_cells_01.cc b/tests/sharedtria/hp_no_cells_01.cc
index 5017aacc9b..9cc842325e 100644
--- a/tests/sharedtria/hp_no_cells_01.cc
+++ b/tests/sharedtria/hp_no_cells_01.cc
@@ -85,7 +85,7 @@ test()
   unsigned int sum = 0;
   for (unsigned int i = 0; i < v.size(); ++i)
     {
-      deallog << v[i] << " ";
+      deallog << v[i] << ' ';
       sum += v[i];
     }
   deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/limit_p_level_difference_04.cc b/tests/sharedtria/limit_p_level_difference_04.cc
index 5dc01deae7..50adee4970 100644
--- a/tests/sharedtria/limit_p_level_difference_04.cc
+++ b/tests/sharedtria/limit_p_level_difference_04.cc
@@ -98,7 +98,7 @@ test(const unsigned int max_difference, const bool allow_artificial_cells)
   deallog << "future FE indices before adaptation:" << std::endl;
   for (const auto &cell :
        dofh.active_cell_iterators() | IteratorFilters::LocallyOwnedCell())
-    deallog << " " << cell->id().to_string() << " " << cell->future_fe_index()
+    deallog << ' ' << cell->id().to_string() << ' ' << cell->future_fe_index()
             << std::endl;
 
   tria.execute_coarsening_and_refinement();
@@ -106,7 +106,7 @@ test(const unsigned int max_difference, const bool allow_artificial_cells)
   deallog << "active FE indices after adaptation:" << std::endl;
   for (const auto &cell :
        dofh.active_cell_iterators() | IteratorFilters::LocallyOwnedCell())
-    deallog << " " << cell->id().to_string() << " " << cell->active_fe_index()
+    deallog << ' ' << cell->id().to_string() << ' ' << cell->active_fe_index()
             << std::endl;
 
   deallog << "OK" << std::endl;
diff --git a/tests/sharedtria/mg_dof_02.cc b/tests/sharedtria/mg_dof_02.cc
index 04e9d7908a..f9918cbda8 100644
--- a/tests/sharedtria/mg_dof_02.cc
+++ b/tests/sharedtria/mg_dof_02.cc
@@ -72,7 +72,7 @@ write_dof_data(DoFHandler<dim> &dof_handler)
                   << ", "
                   << "cell " << cell->id() << ", mg_dof_indices: ";
           for (unsigned int i = 0; i < fe.dofs_per_cell; ++i)
-            deallog << local_mg_dof_indices[i] << " ";
+            deallog << local_mg_dof_indices[i] << ' ';
           deallog << std::endl;
         }
     }
@@ -119,7 +119,7 @@ test()
          tria.level_ghost_owners().begin();
        it != tria.level_ghost_owners().end();
        ++it)
-    deallog << *it << " ";
+    deallog << *it << ' ';
   deallog << std::endl;
 
   write_dof_data(dof_handler);
diff --git a/tests/sharedtria/no_cells_01.cc b/tests/sharedtria/no_cells_01.cc
index 265a8f8d3e..512d8737ba 100644
--- a/tests/sharedtria/no_cells_01.cc
+++ b/tests/sharedtria/no_cells_01.cc
@@ -79,7 +79,7 @@ test()
   unsigned int sum = 0;
   for (unsigned int i = 0; i < v.size(); ++i)
     {
-      deallog << v[i] << " ";
+      deallog << v[i] << ' ';
       sum += v[i];
     }
   deallog << " sum: " << sum << std::endl;
diff --git a/tests/sharedtria/tria_01.cc b/tests/sharedtria/tria_01.cc
index f21cd40371..26d2558296 100644
--- a/tests/sharedtria/tria_01.cc
+++ b/tests/sharedtria/tria_01.cc
@@ -94,7 +94,7 @@ test()
   /*deallog << "n_locally_owned_active_cells_per_processor: ";
   std::vector<unsigned int> v = tr.n_locally_owned_active_cells_per_processor();
   for (unsigned int i=0;i<v.size();++i)
-    deallog << v[i] << " ";
+    deallog << v[i] << ' ';
     deallog << std::endl;*/
 
   // until parmetis is stable, do not output partitioning
@@ -107,7 +107,7 @@ test()
       // cell->subdomain_id()
       AssertThrow(true_subdomain_ids_of_cells[index] == it->subdomain_id(),
                   ExcInternalError());
-      // deallog << it->subdomain_id() << " ";
+      // deallog << it->subdomain_id() << ' ';
     }
   deallog << std::endl;
 
diff --git a/tests/sharedtria/tria_02.cc b/tests/sharedtria/tria_02.cc
index 426d2b7043..d757989b16 100644
--- a/tests/sharedtria/tria_02.cc
+++ b/tests/sharedtria/tria_02.cc
@@ -97,7 +97,7 @@ test()
   /*deallog << "n_locally_owned_active_cells_per_processor: ";
   std::vector<unsigned int> v = tr.n_locally_owned_active_cells_per_processor();
   for (unsigned int i=0;i<v.size();++i)
-    deallog << v[i] << " ";
+    deallog << v[i] << ' ';
     deallog << std::endl;*/
 
   // until parmetis is stable, do not output partitioning
@@ -111,7 +111,7 @@ test()
       AssertThrow((it->is_artificial() == true) ||
                     (true_subdomain_ids_of_cells[index] == it->subdomain_id()),
                   ExcInternalError());
-      // deallog << (int) it->subdomain_id() << " ";
+      // deallog << (int) it->subdomain_id() << ' ';
     }
   deallog << std::endl;
 
diff --git a/tests/sharedtria/tria_custom_refine01.cc b/tests/sharedtria/tria_custom_refine01.cc
index 617ae7c03d..4fdf16e2c1 100644
--- a/tests/sharedtria/tria_custom_refine01.cc
+++ b/tests/sharedtria/tria_custom_refine01.cc
@@ -76,8 +76,8 @@ test()
                                                     endc = shared_tria.end();
   for (; cell != endc; ++cell)
     if (cell->subdomain_id() != numbers::artificial_subdomain_id)
-      deallog << "(" << cell->id().to_string() << "," << cell->subdomain_id()
-              << ")" << std::endl;
+      deallog << '(' << cell->id().to_string() << ',' << cell->subdomain_id()
+              << ')' << std::endl;
 }
 
 int
diff --git a/tests/sharedtria/tria_custom_refine01_cxx11.cc b/tests/sharedtria/tria_custom_refine01_cxx11.cc
index a76f172e3b..911c2272a5 100644
--- a/tests/sharedtria/tria_custom_refine01_cxx11.cc
+++ b/tests/sharedtria/tria_custom_refine01_cxx11.cc
@@ -76,8 +76,8 @@ test()
                                                     endc = shared_tria.end();
   for (; cell != endc; ++cell)
     if (cell->subdomain_id() != numbers::artificial_subdomain_id)
-      deallog << "(" << cell->id().to_string() << "," << cell->subdomain_id()
-              << ")" << std::endl;
+      deallog << '(' << cell->id().to_string() << ',' << cell->subdomain_id()
+              << ')' << std::endl;
 }
 
 int
diff --git a/tests/sharedtria/tria_custom_refine02.cc b/tests/sharedtria/tria_custom_refine02.cc
index 215bf74dc3..9d8ea43de0 100644
--- a/tests/sharedtria/tria_custom_refine02.cc
+++ b/tests/sharedtria/tria_custom_refine02.cc
@@ -89,8 +89,8 @@ test()
                                                       endc = shared_tria.end();
     for (; cell != endc; ++cell)
       if (cell->subdomain_id() != numbers::artificial_subdomain_id)
-        deallog << "(" << cell->id().to_string() << "," << cell->subdomain_id()
-                << ")" << std::endl;
+        deallog << '(' << cell->id().to_string() << ',' << cell->subdomain_id()
+                << ')' << std::endl;
   }
 
   {
@@ -99,8 +99,8 @@ test()
                                                endc = shared_tria.end();
     for (; cell != endc; ++cell)
       if (cell->level_subdomain_id() != numbers::artificial_subdomain_id)
-        deallog << "(" << cell->id().to_string() << ","
-                << cell->level_subdomain_id() << ")" << std::endl;
+        deallog << '(' << cell->id().to_string() << ','
+                << cell->level_subdomain_id() << ')' << std::endl;
   }
 }
 
diff --git a/tests/sharedtria/tria_multigrid_02.cc b/tests/sharedtria/tria_multigrid_02.cc
index 07d677fcb6..1d77c7f1a7 100644
--- a/tests/sharedtria/tria_multigrid_02.cc
+++ b/tests/sharedtria/tria_multigrid_02.cc
@@ -79,8 +79,8 @@ test()
                                                  endc = shared_tria.end(lvl);
       for (; cell != endc; ++cell)
         if (cell->level_subdomain_id() != numbers::artificial_subdomain_id)
-          deallog << "(" << cell->id().to_string() << ","
-                  << cell->level_subdomain_id() << ")" << std::endl;
+          deallog << '(' << cell->id().to_string() << ','
+                  << cell->level_subdomain_id() << ')' << std::endl;
     }
 }
 
diff --git a/tests/sharedtria/tria_zorder_02.cc b/tests/sharedtria/tria_zorder_02.cc
index 2c78d7c331..02cde04fdf 100644
--- a/tests/sharedtria/tria_zorder_02.cc
+++ b/tests/sharedtria/tria_zorder_02.cc
@@ -77,8 +77,8 @@ test()
                                                     endc = shared_tria.end();
   for (; cell != endc; ++cell)
     if (cell->is_locally_owned())
-      deallog << "(" << cell->id().to_string() << "," << cell->subdomain_id()
-              << ")" << std::endl;
+      deallog << '(' << cell->id().to_string() << ',' << cell->subdomain_id()
+              << ')' << std::endl;
 }
 
 int
diff --git a/tests/simplex/cell_measure_01.cc b/tests/simplex/cell_measure_01.cc
index db0a096d1c..8c601aa0f5 100644
--- a/tests/simplex/cell_measure_01.cc
+++ b/tests/simplex/cell_measure_01.cc
@@ -37,7 +37,7 @@ process(const std::vector<Point<spacedim>> &vertices,
   Triangulation<dim, spacedim> tria;
   tria.create_triangulation(vertices, cells, SubCellData());
 
-  deallog << "dim=" << dim << " spacedim=" << spacedim << ":" << std::endl;
+  deallog << "dim=" << dim << " spacedim=" << spacedim << ':' << std::endl;
   for (const auto &cell : tria.active_cell_iterators())
     {
       deallog << "measure:  " << cell->measure() << std::endl;
diff --git a/tests/simplex/compute_point_locations_01.cc b/tests/simplex/compute_point_locations_01.cc
index e37b13b50a..86caacbc0d 100644
--- a/tests/simplex/compute_point_locations_01.cc
+++ b/tests/simplex/compute_point_locations_01.cc
@@ -54,18 +54,18 @@ test_in_unit_cube(const std::vector<Point<dim>> &points)
   deallog << "Print out results in " << dim << "D: " << std::endl;
   for (unsigned int i = 0; i < cells.size(); ++i)
     {
-      deallog << "At cell " << i << ":" << std::endl;
+      deallog << "At cell " << i << ':' << std::endl;
       for (unsigned int j = 0; j < qpoints[i].size(); ++j)
         {
           deallog << "    qpoints " << j << ": " << std::endl;
-          deallog << "        reference position  : (" << qpoints[i][j] << ")"
+          deallog << "        reference position  : (" << qpoints[i][j] << ')'
                   << std::endl;
           deallog << "        physical position   : (" << points[indices[i][j]]
-                  << ")" << std::endl;
+                  << ')' << std::endl;
           deallog << "        FE mapping position : ("
                   << mapping.transform_unit_to_real_cell(cells[i],
                                                          qpoints[i][j])
-                  << ")" << std::endl;
+                  << ')' << std::endl;
         }
     }
   deallog << std::endl;
diff --git a/tests/simplex/fe_lib_01.cc b/tests/simplex/fe_lib_01.cc
index d9e45cfb22..30e00f0e95 100644
--- a/tests/simplex/fe_lib_01.cc
+++ b/tests/simplex/fe_lib_01.cc
@@ -38,14 +38,14 @@ test(const FiniteElement<dim, spacedim> &fe)
   deallog << "  n_dofs_per_quad():   ";
   for (unsigned int i = 0; i < (dim == 2 ? 1 : fe.reference_cell().n_faces());
        ++i)
-    deallog << fe.n_dofs_per_quad(i) << " ";
+    deallog << fe.n_dofs_per_quad(i) << ' ';
   deallog << std::endl;
 
   deallog << "  n_dofs_per_hex():    " << fe.n_dofs_per_hex() << std::endl;
 
   deallog << "  n_dofs_per_face():   ";
   for (unsigned int i = 0; i < fe.reference_cell().n_faces(); ++i)
-    deallog << fe.n_dofs_per_face(i) << " ";
+    deallog << fe.n_dofs_per_face(i) << ' ';
   deallog << std::endl;
 
   deallog << "  n_dofs_per_cell():   " << fe.n_dofs_per_cell() << std::endl;
diff --git a/tests/simplex/fe_lib_02.cc b/tests/simplex/fe_lib_02.cc
index a839c62790..005cf28a25 100644
--- a/tests/simplex/fe_lib_02.cc
+++ b/tests/simplex/fe_lib_02.cc
@@ -38,11 +38,11 @@ test(const FiniteElement<dim, spacedim> &fe, const Quadrature<dim> &quad)
     {
       deallog << point << " : " << std::endl;
       for (unsigned int i = 0; i < fe.n_dofs_per_cell(); ++i)
-        deallog << fe.shape_value(i, point) << " ";
+        deallog << fe.shape_value(i, point) << ' ';
       for (unsigned int i = 0; i < fe.n_dofs_per_cell(); ++i)
-        deallog << fe.shape_grad(i, point) << " ";
+        deallog << fe.shape_grad(i, point) << ' ';
       for (unsigned int i = 0; i < fe.n_dofs_per_cell(); ++i)
-        deallog << fe.shape_grad_grad(i, point) << " ";
+        deallog << fe.shape_grad_grad(i, point) << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/simplex/fe_p_bubbles_01.cc b/tests/simplex/fe_p_bubbles_01.cc
index 93a33c28d8..ec7f7fb08d 100644
--- a/tests/simplex/fe_p_bubbles_01.cc
+++ b/tests/simplex/fe_p_bubbles_01.cc
@@ -38,11 +38,11 @@ test(const FiniteElement<dim, spacedim> &fe, const Quadrature<dim> &quad)
     {
       deallog << point << " : " << std::endl;
       for (unsigned int i = 0; i < fe.n_dofs_per_cell(); ++i)
-        deallog << fe.shape_value(i, point) << " ";
+        deallog << fe.shape_value(i, point) << ' ';
       for (unsigned int i = 0; i < fe.n_dofs_per_cell(); ++i)
-        deallog << fe.shape_grad(i, point) << " ";
+        deallog << fe.shape_grad(i, point) << ' ';
       for (unsigned int i = 0; i < fe.n_dofs_per_cell(); ++i)
-        deallog << fe.shape_grad_grad(i, point) << " ";
+        deallog << fe.shape_grad_grad(i, point) << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/simplex/matrix_free_01.cc b/tests/simplex/matrix_free_01.cc
index 3a2da3276c..84bb343125 100644
--- a/tests/simplex/matrix_free_01.cc
+++ b/tests/simplex/matrix_free_01.cc
@@ -286,8 +286,8 @@ test(const unsigned int v, const unsigned int degree, const bool do_helmholtz)
     Assert(std::abs(result_mf.second - result_mb.second) < 1e-8,
            ExcNotImplemented());
 
-    deallog << "dim=" << dim << " ";
-    deallog << "degree=" << degree << " ";
+    deallog << "dim=" << dim << ' ';
+    deallog << "degree=" << degree << ' ';
     deallog << "Type=";
 
     if (do_helmholtz)
diff --git a/tests/simplex/matrix_free_02.cc b/tests/simplex/matrix_free_02.cc
index 48d3649edd..dd30919aeb 100644
--- a/tests/simplex/matrix_free_02.cc
+++ b/tests/simplex/matrix_free_02.cc
@@ -308,15 +308,15 @@ test(const unsigned version, const unsigned int degree, const bool do_helmholtz)
 
     deallog << "mesh=";
     if (version == 0)
-      deallog << "P";
+      deallog << 'P';
     else if (version == 1)
-      deallog << "Q";
+      deallog << 'Q';
     else if (version == 2)
-      deallog << "M";
+      deallog << 'M';
     deallog << " : ";
 
-    deallog << "dim=" << dim << " ";
-    deallog << "degree=" << degree << " ";
+    deallog << "dim=" << dim << ' ';
+    deallog << "degree=" << degree << ' ';
     deallog << "Type=";
 
     if (do_helmholtz)
diff --git a/tests/simplex/matrix_free_03.cc b/tests/simplex/matrix_free_03.cc
index 45d195b14c..fe32d51601 100644
--- a/tests/simplex/matrix_free_03.cc
+++ b/tests/simplex/matrix_free_03.cc
@@ -355,8 +355,8 @@ test(const unsigned int degree)
 
     Vector<double> difference(tria.n_active_cells());
 
-    deallog << "dim=" << dim << " ";
-    deallog << "degree=" << degree << " ";
+    deallog << "dim=" << dim << ' ';
+    deallog << "degree=" << degree << ' ';
 
     VectorTools::integrate_difference(mapping,
                                       dof_handler,
diff --git a/tests/simplex/matrix_free_04.cc b/tests/simplex/matrix_free_04.cc
index 854beb4f4c..e4f30a8dd0 100644
--- a/tests/simplex/matrix_free_04.cc
+++ b/tests/simplex/matrix_free_04.cc
@@ -304,8 +304,8 @@ test(const unsigned version, const unsigned int degree)
 
     Vector<double> difference(tria.n_active_cells());
 
-    deallog << "dim=" << dim << " ";
-    deallog << "degree=" << degree << " ";
+    deallog << "dim=" << dim << ' ';
+    deallog << "degree=" << degree << ' ';
 
     VectorTools::integrate_difference(mappings,
                                       dof_handler,
diff --git a/tests/simplex/matrix_free_range_iteration_01.cc b/tests/simplex/matrix_free_range_iteration_01.cc
index 1638180e5d..0bde5317b2 100644
--- a/tests/simplex/matrix_free_range_iteration_01.cc
+++ b/tests/simplex/matrix_free_range_iteration_01.cc
@@ -129,7 +129,7 @@ test()
       std::sort(i.begin(), i.end());
 
       for (const auto &j : i)
-        deallog << j << " ";
+        deallog << j << ' ';
       deallog << std::endl;
     }
 
@@ -138,7 +138,7 @@ test()
     {
       std::sort(i.begin(), i.end());
       for (const auto &j : i)
-        deallog << j.first << "@" << j.second << "   ";
+        deallog << j.first << '@' << j.second << "   ";
       deallog << std::endl;
     }
 
@@ -149,7 +149,7 @@ test()
         {
           std::sort(i.begin(), i.end());
           for (const auto &j : i)
-            deallog << j.first << "@" << j.second << "   ";
+            deallog << j.first << '@' << j.second << "   ";
           deallog << std::endl;
         }
     }
diff --git a/tests/simplex/orientation_02.cc b/tests/simplex/orientation_02.cc
index 1b5f92b5de..02ddd28bdd 100644
--- a/tests/simplex/orientation_02.cc
+++ b/tests/simplex/orientation_02.cc
@@ -73,7 +73,7 @@ test(const unsigned int orientation)
   cell++;
 
   // check orientation
-  deallog << "face orientation: " << orientation << " " << std::endl;
+  deallog << "face orientation: " << orientation << ' ' << std::endl;
   AssertDimension(orientation,
                   (cell->face_orientation(0) * 1 + cell->face_rotation(0) * 2 +
                    cell->face_flip(0) * 4));
@@ -81,10 +81,10 @@ test(const unsigned int orientation)
   // check vertices
   {
     for (unsigned int v = 0; v < cell->n_vertices(); ++v)
-      deallog << cell->vertex_index(v) << " ";
+      deallog << cell->vertex_index(v) << ' ';
     deallog << " vs. ";
     for (unsigned int v = 0; v < cell->n_vertices(); ++v)
-      deallog << cells[1].vertices[v] << " ";
+      deallog << cells[1].vertices[v] << ' ';
     deallog << std::endl;
 
     for (const auto v : cell->vertex_indices())
@@ -110,7 +110,7 @@ test(const unsigned int orientation)
          cells[1].vertices[(l + 1) % face->n_vertices()]}};
       std::sort(b.begin(), b.end());
 
-      deallog << a[0] << "-" << a[1] << " vs. " << b[0] << "-" << b[1]
+      deallog << a[0] << '-' << a[1] << " vs. " << b[0] << '-' << b[1]
               << std::endl;
 
       AssertDimension(a[0], b[0]);
diff --git a/tests/simplex/poisson_02.cc b/tests/simplex/poisson_02.cc
index 4d9e03c388..65fb68b388 100644
--- a/tests/simplex/poisson_02.cc
+++ b/tests/simplex/poisson_02.cc
@@ -520,7 +520,7 @@ DGHeat<dim>::output_results(unsigned int it) const
 
   std::string fname = dimension + Utilities::int_to_string(it) + ".vtk";
 
-  deallog << "  Writing solution to <" << fname << ">" << std::endl;
+  deallog << "  Writing solution to <" << fname << '>' << std::endl;
 
   std::ofstream output(fname.c_str());
 
diff --git a/tests/simplex/polynomials_01.cc b/tests/simplex/polynomials_01.cc
index 10ea5f4be4..7dd4aedcc6 100644
--- a/tests/simplex/polynomials_01.cc
+++ b/tests/simplex/polynomials_01.cc
@@ -48,11 +48,11 @@ test(const unsigned int degree)
                     fourth_derivatives);
 
       for (auto v : values)
-        deallog << v << " ";
+        deallog << v << ' ';
       deallog << std::endl;
 
       for (auto v : grads)
-        deallog << v << " ";
+        deallog << v << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/simplex/q_iterated_simplex_01.cc b/tests/simplex/q_iterated_simplex_01.cc
index e9904690be..00b8b29c06 100644
--- a/tests/simplex/q_iterated_simplex_01.cc
+++ b/tests/simplex/q_iterated_simplex_01.cc
@@ -27,8 +27,8 @@ print(const Quadrature<dim> &quad)
   deallog << "quad size = " << quad.size() << std::endl;
   for (unsigned int q = 0; q < quad.size(); ++q)
     {
-      deallog << quad.point(q) << " ";
-      deallog << quad.weight(q) << " ";
+      deallog << quad.point(q) << ' ';
+      deallog << quad.weight(q) << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/simplex/q_projection_01.cc b/tests/simplex/q_projection_01.cc
index 19a59203b5..da2aafee68 100644
--- a/tests/simplex/q_projection_01.cc
+++ b/tests/simplex/q_projection_01.cc
@@ -46,7 +46,7 @@ test<2>(const unsigned int n_points)
                          const bool         face_orientation) {
     deallog << "face_no=" << face_no
             << " face_orientation=" << (face_orientation ? "true" : "false")
-            << ":" << std::endl;
+            << ':' << std::endl;
     for (unsigned int
            q = 0,
            i =
@@ -59,8 +59,8 @@ test<2>(const unsigned int n_points)
          q < quad_ref.size();
          ++q, ++i)
       {
-        deallog << quad.point(i) << " ";
-        deallog << quad.weight(i) << " ";
+        deallog << quad.point(i) << ' ';
+        deallog << quad.weight(i) << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
@@ -92,7 +92,7 @@ test<3>(const unsigned int n_points)
     deallog << "face_no=" << face_no
             << " face_orientation=" << (face_orientation ? "true" : "false")
             << " face_flip=" << (face_flip ? "true" : "false")
-            << " face_rotation=" << (face_rotation ? "true" : "false") << ":"
+            << " face_rotation=" << (face_rotation ? "true" : "false") << ':'
             << std::endl;
     for (unsigned int q = 0,
                       i = QProjector<dim>::DataSetDescriptor::face(
@@ -105,8 +105,8 @@ test<3>(const unsigned int n_points)
          q < quad_ref.size();
          ++q, ++i)
       {
-        deallog << quad.point(i) << " ";
-        deallog << quad.weight(i) << " ";
+        deallog << quad.point(i) << ' ';
+        deallog << quad.weight(i) << ' ';
         deallog << std::endl;
       }
     deallog << std::endl;
diff --git a/tests/simplex/q_witherden_vincent_01.cc b/tests/simplex/q_witherden_vincent_01.cc
index 2611b1a8b7..6a8f5ba445 100644
--- a/tests/simplex/q_witherden_vincent_01.cc
+++ b/tests/simplex/q_witherden_vincent_01.cc
@@ -28,8 +28,8 @@ print(const unsigned int n_points_1D)
   deallog << "quad size = " << quad.size() << std::endl;
   for (unsigned int q = 0; q < quad.size(); ++q)
     {
-      deallog << quad.point(q) << " ";
-      deallog << quad.weight(q) << " ";
+      deallog << quad.point(q) << ' ';
+      deallog << quad.weight(q) << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/simplex/qgauss_01.cc b/tests/simplex/qgauss_01.cc
index a517fbb910..1bb1ed0138 100644
--- a/tests/simplex/qgauss_01.cc
+++ b/tests/simplex/qgauss_01.cc
@@ -28,8 +28,8 @@ print(const unsigned int n_points_1D)
   deallog << "quad size = " << quad.size() << std::endl;
   for (unsigned int q = 0; q < quad.size(); ++q)
     {
-      deallog << quad.point(q) << " ";
-      deallog << quad.weight(q) << " ";
+      deallog << quad.point(q) << ' ';
+      deallog << quad.weight(q) << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/simplex/quadrature_lib_01.cc b/tests/simplex/quadrature_lib_01.cc
index 195c440e50..a46a6e1838 100644
--- a/tests/simplex/quadrature_lib_01.cc
+++ b/tests/simplex/quadrature_lib_01.cc
@@ -31,8 +31,8 @@ test(const unsigned int n_points)
 
   for (unsigned int q = 0; q < quad.size(); ++q)
     {
-      deallog << quad.point(q) << " ";
-      deallog << quad.weight(q) << " ";
+      deallog << quad.point(q) << ' ';
+      deallog << quad.weight(q) << ' ';
       deallog << std::endl;
     }
 }
diff --git a/tests/simplex/reference_cell_kind_01.cc b/tests/simplex/reference_cell_kind_01.cc
index 7885dc9b34..4984e9f8f8 100644
--- a/tests/simplex/reference_cell_kind_01.cc
+++ b/tests/simplex/reference_cell_kind_01.cc
@@ -35,7 +35,7 @@ test(const ReferenceCell &reference_cell)
     {
       deallog << v << ": ";
       for (const auto i : kind.faces_for_given_vertex(v))
-        deallog << i << " ";
+        deallog << i << ' ';
       deallog << std::endl;
     }
   deallog << std::endl;
diff --git a/tests/simplex/refinement_02.cc b/tests/simplex/refinement_02.cc
index ba8c03fc71..4f18217959 100644
--- a/tests/simplex/refinement_02.cc
+++ b/tests/simplex/refinement_02.cc
@@ -53,13 +53,13 @@ test(const unsigned int v)
 
   for (const auto &cell : tria.active_cell_iterators())
     {
-      deallog << cell->level() << ":" << cell->index() << "     ";
+      deallog << cell->level() << ':' << cell->index() << "     ";
       for (const auto f : cell->face_indices())
         if (cell->at_boundary(f))
           deallog << "-:- ";
         else
-          deallog << cell->neighbor_level(f) << ":" << cell->neighbor_index(f)
-                  << " ";
+          deallog << cell->neighbor_level(f) << ':' << cell->neighbor_index(f)
+                  << ' ';
       deallog << std::endl;
     }
 
diff --git a/tests/simplex/step-12.cc b/tests/simplex/step-12.cc
index 9e3ab2fd4b..bb66a5bd39 100644
--- a/tests/simplex/step-12.cc
+++ b/tests/simplex/step-12.cc
@@ -420,7 +420,7 @@ namespace Step12
   AdvectionProblem<dim>::output_results(const unsigned int cycle) const
   {
     const std::string filename = "solution-" + std::to_string(cycle) + ".vtk";
-    std::cout << "  Writing solution to <" << filename << ">" << std::endl;
+    std::cout << "  Writing solution to <" << filename << '>' << std::endl;
     std::ofstream output(filename);
 
     DataOut<dim> data_out;
diff --git a/tests/simplex/step-12a.cc b/tests/simplex/step-12a.cc
index 3b4dc50238..9f4b3170c7 100644
--- a/tests/simplex/step-12a.cc
+++ b/tests/simplex/step-12a.cc
@@ -473,7 +473,7 @@ namespace Step12
       dim == 2 ? ("step12-tri-" + std::to_string(cycle) + ".vtk") :
                  ("step12-tet-" + std::to_string(cycle) + ".vtk");
 #  endif
-    deallog << "  Writing solution to <" << filename << ">" << std::endl;
+    deallog << "  Writing solution to <" << filename << '>' << std::endl;
     std::ofstream output(filename);
 
     DataOut<dim> data_out;
diff --git a/tests/simplex/step-17.cc b/tests/simplex/step-17.cc
index 52531733a0..4dbc28394e 100644
--- a/tests/simplex/step-17.cc
+++ b/tests/simplex/step-17.cc
@@ -438,7 +438,7 @@ namespace Step17
       deallog << (p == 0 ? ' ' : '+')
               << (DoFTools::count_dofs_with_subdomain_association(dof_handler,
                                                                   p));
-    deallog << ")" << std::endl;
+    deallog << ')' << std::endl;
 
     assemble_system();
     solve();
diff --git a/tests/simplex/step-18.cc b/tests/simplex/step-18.cc
index efe3253dac..f7ce0eaa94 100644
--- a/tests/simplex/step-18.cc
+++ b/tests/simplex/step-18.cc
@@ -720,7 +720,7 @@ namespace Step18
     deallog.depth_file(previous_depth);
 
     deallog << "norm: " << distributed_incremental_displacement.linfty_norm()
-            << " " << distributed_incremental_displacement.l1_norm() << " "
+            << ' ' << distributed_incremental_displacement.l1_norm() << ' '
             << distributed_incremental_displacement.l2_norm() << std::endl;
 
     incremental_displacement = distributed_incremental_displacement;
@@ -823,7 +823,7 @@ namespace Step18
           deallog << (p == 0 ? ' ' : '+')
                   << (GridTools::count_cells_with_subdomain_association(
                        triangulation, p));
-        deallog << ")" << std::endl;
+        deallog << ')' << std::endl;
 
         setup_system();
 
@@ -833,7 +833,7 @@ namespace Step18
           deallog << (p == 0 ? ' ' : '+')
                   << (DoFTools::count_dofs_with_subdomain_association(
                        dof_handler, p));
-        deallog << ")" << std::endl;
+        deallog << ')' << std::endl;
 
         solve_timestep();
       }
diff --git a/tests/simplex/step-67.cc b/tests/simplex/step-67.cc
index fd8f2cb576..9d49d2a812 100644
--- a/tests/simplex/step-67.cc
+++ b/tests/simplex/step-67.cc
@@ -2393,10 +2393,10 @@ namespace Euler_DG
       pcout << "Running with "
             << Utilities::MPI::n_mpi_processes(MPI_COMM_WORLD)
             << " MPI processes" << std::endl;
-      pcout << "Vectorization over " << n_vect_number << " "
+      pcout << "Vectorization over " << n_vect_number << ' '
             << (std::is_same<Number, double>::value ? "doubles" : "floats")
             << " = " << n_vect_bits << " bits ("
-            << Utilities::System::get_current_vectorization_level() << ")"
+            << Utilities::System::get_current_vectorization_level() << ')'
             << std::endl;
       */
     }
diff --git a/tests/simplex/variable_face_quadratures_01.cc b/tests/simplex/variable_face_quadratures_01.cc
index 08732a3b10..f77b0863c3 100644
--- a/tests/simplex/variable_face_quadratures_01.cc
+++ b/tests/simplex/variable_face_quadratures_01.cc
@@ -79,7 +79,7 @@ test<2>()
                                             quad_ref);
 
     const auto print = [&](const unsigned int face_no) {
-      deallog << "face_no=" << face_no << ":" << std::endl;
+      deallog << "face_no=" << face_no << ':' << std::endl;
       for (unsigned int q = 0,
                         i = QProjector<dim>::DataSetDescriptor::face(
                           ReferenceCells::Quadrilateral,
@@ -91,8 +91,8 @@ test<2>()
            q < quad_ref[face_no].size();
            ++q, ++i)
         {
-          deallog << quad.point(i) << " ";
-          deallog << quad.weight(i) << " ";
+          deallog << quad.point(i) << ' ';
+          deallog << quad.weight(i) << ' ';
           deallog << std::endl;
         }
       deallog << std::endl;
@@ -130,11 +130,11 @@ test<2>()
         {
           mapping.fill_fe_face_values(cell, face_no, quad_ref, *data_ref, data);
 
-          deallog << "face_no=" << face_no << ":" << std::endl;
+          deallog << "face_no=" << face_no << ':' << std::endl;
           for (unsigned int q = 0; q < quad_ref[face_no].size(); ++q)
             {
-              deallog << data.quadrature_points[q] << " ";
-              deallog << data.JxW_values[q] << " ";
+              deallog << data.quadrature_points[q] << ' ';
+              deallog << data.JxW_values[q] << ' ';
               deallog << std::endl;
             }
           deallog << std::endl;
@@ -200,7 +200,7 @@ test<2>()
           fe_face_values.get_function_values(vector_1, values_1);
 
           for (unsigned int q = 0; q < values_0.size(); ++q)
-            deallog << values_0[q] << " " << values_1[q] << " " << std::endl;
+            deallog << values_0[q] << ' ' << values_1[q] << ' ' << std::endl;
 
           deallog << std::endl;
         }
@@ -241,10 +241,10 @@ test<2>()
                                                Vector<double>(dim));
           fe_face_values.get_function_values(vector_0, values_0);
 
-          deallog << "face_no=" << face_no << ":" << std::endl;
+          deallog << "face_no=" << face_no << ':' << std::endl;
 
           for (unsigned int q = 0; q < values_0.size(); ++q)
-            deallog << values_0[q][0] << " " << values_0[q][1] << " "
+            deallog << values_0[q][0] << ' ' << values_0[q][1] << ' '
                     << std::endl;
 
           deallog << std::endl;
@@ -295,11 +295,11 @@ test<3>()
                                                Vector<double>(dim));
           fe_face_values.get_function_values(vector_0, values_0);
 
-          deallog << "face_no=" << face_no << ":" << std::endl;
+          deallog << "face_no=" << face_no << ':' << std::endl;
 
           for (unsigned int q = 0; q < values_0.size(); ++q)
-            deallog << values_0[q][0] << " " << values_0[q][1] << " "
-                    << values_0[q][2] << " " << std::endl;
+            deallog << values_0[q][0] << ' ' << values_0[q][1] << ' '
+                    << values_0[q][2] << ' ' << std::endl;
 
           deallog << std::endl;
         }
diff --git a/tests/simplex/variable_face_quadratures_02.cc b/tests/simplex/variable_face_quadratures_02.cc
index 609372a3f8..ff6c40bddc 100644
--- a/tests/simplex/variable_face_quadratures_02.cc
+++ b/tests/simplex/variable_face_quadratures_02.cc
@@ -114,11 +114,11 @@ test<2>()
             fe_face_values.get_present_fe_values().get_function_values(
               vector_0, values_0);
 
-            deallog << "q_index=" << q_index << " face_no=" << face_no << ":"
+            deallog << "q_index=" << q_index << " face_no=" << face_no << ':'
                     << std::endl;
 
             for (unsigned int q = 0; q < values_0.size(); ++q)
-              deallog << values_0[q][0] << " " << values_0[q][1] << " "
+              deallog << values_0[q][0] << ' ' << values_0[q][1] << ' '
                       << std::endl;
 
             deallog << std::endl;
diff --git a/tests/simplex/variable_face_quadratures_03.cc b/tests/simplex/variable_face_quadratures_03.cc
index 7b680696ce..79856b1257 100644
--- a/tests/simplex/variable_face_quadratures_03.cc
+++ b/tests/simplex/variable_face_quadratures_03.cc
@@ -104,10 +104,10 @@ test<2>()
                                                  Vector<double>(dim));
             fe_face_values.get_function_values(vector_0, values_0);
 
-            deallog << "face_no=" << face_no << ":" << std::endl;
+            deallog << "face_no=" << face_no << ':' << std::endl;
 
             for (unsigned int q = 0; q < values_0.size(); ++q)
-              deallog << values_0[q][0] << " " << values_0[q][1] << " "
+              deallog << values_0[q][0] << ' ' << values_0[q][1] << ' '
                       << std::endl;
 
             deallog << std::endl;
@@ -158,11 +158,11 @@ test<3>()
                                                  Vector<double>(dim));
             fe_face_values.get_function_values(vector_0, values_0);
 
-            deallog << "face_no=" << face_no << ":" << std::endl;
+            deallog << "face_no=" << face_no << ':' << std::endl;
 
             for (unsigned int q = 0; q < values_0.size(); ++q)
-              deallog << values_0[q][0] << " " << values_0[q][1] << " "
-                      << " " << values_0[q][2] << " " << std::endl;
+              deallog << values_0[q][0] << ' ' << values_0[q][1] << ' ' << ' '
+                      << values_0[q][2] << ' ' << std::endl;
 
             deallog << std::endl;
           }
diff --git a/tests/simplex/wedge_01.cc b/tests/simplex/wedge_01.cc
index 1b197328cb..7cae40373c 100644
--- a/tests/simplex/wedge_01.cc
+++ b/tests/simplex/wedge_01.cc
@@ -101,7 +101,7 @@ test_3()
           cell->face(face)->get_dof_indices(dof_indices);
 
           for (const auto i : dof_indices)
-            deallog << i << " ";
+            deallog << i << ' ';
           deallog << std::endl;
         }
     }
diff --git a/tests/slepc/solve_01.cc b/tests/slepc/solve_01.cc
index ab37a707d0..4c90cb88ae 100644
--- a/tests/slepc/solve_01.cc
+++ b/tests/slepc/solve_01.cc
@@ -75,9 +75,9 @@ check_solve(SolverType &              solver,
   deallog << "Eigenvalues:";
   for (unsigned int i = 0; i < v.size(); ++i)
     {
-      deallog << " " << v[i];
+      deallog << ' ' << v[i];
       if (i != (v.size() - 1))
-        deallog << ",";
+        deallog << ',';
     }
   deallog << std::endl << std::endl;
 }
diff --git a/tests/slepc/solve_04.cc b/tests/slepc/solve_04.cc
index 16fcc0c32b..6f890b201c 100644
--- a/tests/slepc/solve_04.cc
+++ b/tests/slepc/solve_04.cc
@@ -110,9 +110,9 @@ check_solve(SolverType &              solver,
   deallog << "Eigenvalues:";
   for (unsigned int i = 0; i < v.size(); ++i)
     {
-      deallog << " " << v[i];
+      deallog << ' ' << v[i];
       if (i != (v.size() - 1))
-        deallog << ",";
+        deallog << ',';
     }
   deallog << std::endl << std::endl;
 }
diff --git a/tests/sparsity/block_dynamic_01.cc b/tests/sparsity/block_dynamic_01.cc
index 9c66b6d2cc..d2009d8a72 100644
--- a/tests/sparsity/block_dynamic_01.cc
+++ b/tests/sparsity/block_dynamic_01.cc
@@ -41,10 +41,10 @@ main()
   csp.add(1, 2);
   csp.compress();
 
-  deallog << "blocks: " << csp.n_block_rows() << "x" << csp.n_block_cols()
+  deallog << "blocks: " << csp.n_block_rows() << 'x' << csp.n_block_cols()
           << std::endl;
-  deallog << "size: " << csp.n_rows() << "x" << csp.n_cols() << std::endl;
-  deallog << "size block(1,0):" << csp.block(1, 0).n_rows() << "x"
+  deallog << "size: " << csp.n_rows() << 'x' << csp.n_cols() << std::endl;
+  deallog << "size block(1,0):" << csp.block(1, 0).n_rows() << 'x'
           << csp.block(1, 0).n_cols() << std::endl;
 
   csp.print(deallog.get_file_stream());
@@ -55,7 +55,7 @@ main()
       deallog << "row " << i << ": ";
 
       for (unsigned int j = 0; j < csp.row_length(i); ++j)
-        deallog << csp.column_number(i, j) << " ";
+        deallog << csp.column_number(i, j) << ' ';
 
       deallog << std::endl;
     }
diff --git a/tests/sparsity/block_dynamic_sparsity_pattern_indexset_01.cc b/tests/sparsity/block_dynamic_sparsity_pattern_indexset_01.cc
index ba443bd7a4..d8bf511dfe 100644
--- a/tests/sparsity/block_dynamic_sparsity_pattern_indexset_01.cc
+++ b/tests/sparsity/block_dynamic_sparsity_pattern_indexset_01.cc
@@ -40,19 +40,19 @@ main()
   part.push_back(a);
   BlockDynamicSparsityPattern csp(part);
 
-  deallog << "blocks: " << csp.n_block_rows() << "x" << csp.n_block_cols()
+  deallog << "blocks: " << csp.n_block_rows() << 'x' << csp.n_block_cols()
           << std::endl;
-  deallog << "size: " << csp.n_rows() << "x" << csp.n_cols() << std::endl;
-  deallog << "size block(1,0):" << csp.block(1, 0).n_rows() << "x"
+  deallog << "size: " << csp.n_rows() << 'x' << csp.n_cols() << std::endl;
+  deallog << "size block(1,0):" << csp.block(1, 0).n_rows() << 'x'
           << csp.block(1, 0).n_cols() << std::endl;
 
   part.pop_back();
   csp.reinit(part); // also check the reinit variant.
 
-  deallog << "blocks: " << csp.n_block_rows() << "x" << csp.n_block_cols()
+  deallog << "blocks: " << csp.n_block_rows() << 'x' << csp.n_block_cols()
           << std::endl;
-  deallog << "size: " << csp.n_rows() << "x" << csp.n_cols() << std::endl;
-  deallog << "size block(1,0):" << csp.block(1, 0).n_rows() << "x"
+  deallog << "size: " << csp.n_rows() << 'x' << csp.n_cols() << std::endl;
+  deallog << "size block(1,0):" << csp.block(1, 0).n_rows() << 'x'
           << csp.block(1, 0).n_cols() << std::endl;
 
   for (int i = 0; i < 13; ++i)
diff --git a/tests/sparsity/block_sparsity_pattern_03.cc b/tests/sparsity/block_sparsity_pattern_03.cc
index ca79782588..3ef460875d 100644
--- a/tests/sparsity/block_sparsity_pattern_03.cc
+++ b/tests/sparsity/block_sparsity_pattern_03.cc
@@ -54,7 +54,7 @@ main()
       for (types::global_dof_index c = 0; c < rlen; ++c)
         {
           types::global_dof_index column = csp.column_number(row, c);
-          deallog << row << "," << column << std::endl;
+          deallog << row << ',' << column << std::endl;
         }
     }
 
diff --git a/tests/sparsity/dynamic_sparsity_pattern_23.cc b/tests/sparsity/dynamic_sparsity_pattern_23.cc
index 597abf9b6c..37c2dd6905 100644
--- a/tests/sparsity/dynamic_sparsity_pattern_23.cc
+++ b/tests/sparsity/dynamic_sparsity_pattern_23.cc
@@ -49,7 +49,7 @@ test()
       deallog << "Row " << row << " has the column indices: ";
       for (auto it = sp.begin(row); it != sp.end(row); ++it)
         {
-          deallog << it->column() << " ";
+          deallog << it->column() << ' ';
         }
       deallog << std::endl;
     }
diff --git a/tests/sparsity/dynamic_sparsity_pattern_iterator_04.cc b/tests/sparsity/dynamic_sparsity_pattern_iterator_04.cc
index 2c157a75cd..96e8ee481c 100644
--- a/tests/sparsity/dynamic_sparsity_pattern_iterator_04.cc
+++ b/tests/sparsity/dynamic_sparsity_pattern_iterator_04.cc
@@ -72,7 +72,7 @@ iterate(DynamicSparsityPattern &sp)
       {
         DynamicSparsityPattern::iterator col     = sp.begin(row),
                                          end_col = sp.end(row);
-        deallog << "row " << row << ":" << std::endl;
+        deallog << "row " << row << ':' << std::endl;
         for (; col != end_col; ++col)
           {
             deallog << "row= " << col->row() << ", col= " << col->column()
diff --git a/tests/sparsity/sparsity_pattern.cc b/tests/sparsity/sparsity_pattern.cc
index 88a9095f7a..ca60b91ecd 100644
--- a/tests/sparsity/sparsity_pattern.cc
+++ b/tests/sparsity/sparsity_pattern.cc
@@ -36,8 +36,8 @@ main()
   SparsityPattern    sp1((N - 1) * (N - 1), (N - 1) * (N - 1), 5);
   FDMatrix(N, N).five_point_structure(sp1);
   sp1.compress();
-  deallog << sp1.n_rows() << " " << sp1.n_cols() << " " << sp1.bandwidth()
-          << " " << sp1.n_nonzero_elements() << std::endl;
+  deallog << sp1.n_rows() << ' ' << sp1.n_cols() << ' ' << sp1.bandwidth()
+          << ' ' << sp1.n_nonzero_elements() << std::endl;
   for (unsigned int i = 0; i < sp1.n_rows(); ++i)
     deallog << sp1.row_length(i) << std::endl;
   sp1.print_gnuplot(deallog.get_file_stream());
@@ -46,8 +46,8 @@ main()
   // off-diagonals
   SparsityPattern sp2(sp1, 10, 2);
   sp2.compress();
-  deallog << sp2.n_rows() << " " << sp2.n_cols() << " " << sp2.bandwidth()
-          << " " << sp2.n_nonzero_elements() << std::endl;
+  deallog << sp2.n_rows() << ' ' << sp2.n_cols() << ' ' << sp2.bandwidth()
+          << ' ' << sp2.n_nonzero_elements() << std::endl;
   for (unsigned int i = 0; i < sp2.n_rows(); ++i)
     deallog << sp2.row_length(i) << std::endl;
   sp2.print_gnuplot(deallog.get_file_stream());
@@ -62,8 +62,8 @@ main()
     sp3.add(0, i);
   sp3.symmetrize();
   sp3.compress();
-  deallog << sp3.n_rows() << " " << sp3.n_cols() << " " << sp3.bandwidth()
-          << " " << sp3.n_nonzero_elements() << std::endl;
+  deallog << sp3.n_rows() << ' ' << sp3.n_cols() << ' ' << sp3.bandwidth()
+          << ' ' << sp3.n_nonzero_elements() << std::endl;
   for (unsigned int i = 0; i < sp3.n_rows(); ++i)
     deallog << sp3.row_length(i) << std::endl;
   sp3.print_gnuplot(deallog.get_file_stream());
diff --git a/tests/sundials/arkode_01.cc b/tests/sundials/arkode_01.cc
index 14d42e7ff5..6d7279d38f 100644
--- a/tests/sundials/arkode_01.cc
+++ b/tests/sundials/arkode_01.cc
@@ -88,7 +88,7 @@ main(int argc, char **argv)
   ode.output_step = [&](const double       t,
                         const VectorType & sol,
                         const unsigned int step_number) -> int {
-    deallog << t << " " << sol[0] << " " << sol[1] << std::endl;
+    deallog << t << ' ' << sol[0] << ' ' << sol[1] << std::endl;
     return 0;
   };
 
diff --git a/tests/sundials/arkode_02.cc b/tests/sundials/arkode_02.cc
index 713deac468..00217ce71b 100644
--- a/tests/sundials/arkode_02.cc
+++ b/tests/sundials/arkode_02.cc
@@ -84,7 +84,7 @@ main(int argc, char **argv)
     // limit the output to every 10th step and increase the precision to make
     // the test more robust
     if (step_number % 10 == 0)
-      deallog << t << " " << std::setprecision(7) << sol[0] << " " << sol[1]
+      deallog << t << ' ' << std::setprecision(7) << sol[0] << ' ' << sol[1]
               << std::endl;
     return 0;
   };
diff --git a/tests/sundials/arkode_03.cc b/tests/sundials/arkode_03.cc
index 11870cda21..521b6e269c 100644
--- a/tests/sundials/arkode_03.cc
+++ b/tests/sundials/arkode_03.cc
@@ -98,8 +98,8 @@ main(int argc, char **argv)
     // limit the output to every 10th step and increase the precision to make
     // the test more robust
     if (step_number % 10 == 0)
-      deallog << t << " " << std::setprecision(10) << sol[0] << " " << sol[1]
-              << " " << sol[2] << std::endl;
+      deallog << t << ' ' << std::setprecision(10) << sol[0] << ' ' << sol[1]
+              << ' ' << sol[2] << std::endl;
     return 0;
   };
 
diff --git a/tests/sundials/arkode_04.cc b/tests/sundials/arkode_04.cc
index 8314572b89..158d1619b5 100644
--- a/tests/sundials/arkode_04.cc
+++ b/tests/sundials/arkode_04.cc
@@ -112,7 +112,7 @@ main(int argc, char **argv)
   ode.output_step = [&](const double       t,
                         const VectorType & sol,
                         const unsigned int step_number) -> int {
-    deallog << t << " " << sol[0] << " " << sol[1] << " " << sol[2]
+    deallog << t << ' ' << sol[0] << ' ' << sol[1] << ' ' << sol[2]
             << std::endl;
     return 0;
   };
diff --git a/tests/sundials/arkode_05.cc b/tests/sundials/arkode_05.cc
index a0569c9fc5..a74dd5aea9 100644
--- a/tests/sundials/arkode_05.cc
+++ b/tests/sundials/arkode_05.cc
@@ -123,7 +123,7 @@ main(int argc, char **argv)
   ode.output_step = [&](const double       t,
                         const VectorType & sol,
                         const unsigned int step_number) -> int {
-    deallog << t << " " << sol[0] << " " << sol[1] << " " << sol[2]
+    deallog << t << ' ' << sol[0] << ' ' << sol[1] << ' ' << sol[2]
             << std::endl;
     return 0;
   };
diff --git a/tests/sundials/arkode_06.cc b/tests/sundials/arkode_06.cc
index 4fc58593ac..ca7dda566a 100644
--- a/tests/sundials/arkode_06.cc
+++ b/tests/sundials/arkode_06.cc
@@ -133,7 +133,7 @@ main(int argc, char **argv)
   ode.output_step = [&](const double       t,
                         const VectorType & sol,
                         const unsigned int step_number) -> int {
-    deallog << t << " " << sol[0] << " " << sol[1] << " " << sol[2]
+    deallog << t << ' ' << sol[0] << ' ' << sol[1] << ' ' << sol[2]
             << std::endl;
     return 0;
   };
diff --git a/tests/sundials/arkode_07.cc b/tests/sundials/arkode_07.cc
index ff0d21ca2f..4cf77ad37a 100644
--- a/tests/sundials/arkode_07.cc
+++ b/tests/sundials/arkode_07.cc
@@ -157,7 +157,7 @@ main(int argc, char **argv)
   ode.output_step = [&](const double       t,
                         const VectorType & sol,
                         const unsigned int step_number) -> int {
-    deallog << t << " " << sol[0] << " " << sol[1] << " " << sol[2]
+    deallog << t << ' ' << sol[0] << ' ' << sol[1] << ' ' << sol[2]
             << std::endl;
     return 0;
   };
diff --git a/tests/sundials/arkode_08.cc b/tests/sundials/arkode_08.cc
index 2bb10962e0..3bd6e909f5 100644
--- a/tests/sundials/arkode_08.cc
+++ b/tests/sundials/arkode_08.cc
@@ -148,7 +148,7 @@ main(int argc, char **argv)
   ode.output_step = [&](const double       t,
                         const VectorType & sol,
                         const unsigned int step_number) -> int {
-    deallog << t << " " << sol[0] << " " << sol[1] << std::endl;
+    deallog << t << ' ' << sol[0] << ' ' << sol[1] << std::endl;
     return 0;
   };
 
diff --git a/tests/sundials/arkode_repeated_solve.cc b/tests/sundials/arkode_repeated_solve.cc
index ad4a62939f..3e55a8c8bb 100644
--- a/tests/sundials/arkode_repeated_solve.cc
+++ b/tests/sundials/arkode_repeated_solve.cc
@@ -51,7 +51,7 @@ create_solver()
   ode->output_step = [&](const double       t,
                          const VectorType & sol,
                          const unsigned int step_number) -> int {
-    deallog << t << " " << sol[0] << " " << sol[1] << std::endl;
+    deallog << t << ' ' << sol[0] << ' ' << sol[1] << std::endl;
     return 0;
   };
   return ode;
diff --git a/tests/sundials/ida_01.cc b/tests/sundials/ida_01.cc
index 7d87619d3c..2ca579f713 100644
--- a/tests/sundials/ida_01.cc
+++ b/tests/sundials/ida_01.cc
@@ -117,7 +117,7 @@ public:
                                    const VectorType & sol,
                                    const VectorType & sol_dot,
                                    const unsigned int step_number) -> int {
-      out << t << " " << sol[0] << " " << sol[1] << " " << sol_dot[0] << " "
+      out << t << ' ' << sol[0] << ' ' << sol[1] << ' ' << sol_dot[0] << ' '
           << sol_dot[1] << std::endl;
       return 0;
     };
diff --git a/tests/sundials/ida_02.cc b/tests/sundials/ida_02.cc
index 73e556ff98..717fd9328d 100644
--- a/tests/sundials/ida_02.cc
+++ b/tests/sundials/ida_02.cc
@@ -114,7 +114,7 @@ public:
                                    const VectorType & sol,
                                    const VectorType & sol_dot,
                                    const unsigned int step_number) -> int {
-      out << t << " " << sol[0] << " " << sol[1] << " " << sol_dot[0] << " "
+      out << t << ' ' << sol[0] << ' ' << sol[1] << ' ' << sol_dot[0] << ' '
           << sol_dot[1] << std::endl;
       return 0;
     };
diff --git a/tests/sundials/kinsol_03.cc b/tests/sundials/kinsol_03.cc
index 1c2c5ebee6..d62b747344 100644
--- a/tests/sundials/kinsol_03.cc
+++ b/tests/sundials/kinsol_03.cc
@@ -69,7 +69,7 @@ main(int argc, char **argv)
   kinsol.reinit_vector = [N](VectorType &v) { v.reinit(N); };
 
   kinsol.residual = [](const VectorType &u, VectorType &F) -> int {
-    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     F(0) = std::cos(u[0] + u[1]) - 1 + 2 * u[0];
@@ -93,7 +93,7 @@ main(int argc, char **argv)
   kinsol.setup_jacobian = [](const VectorType &u, const VectorType &F) -> int {
     // We don't do any kind of set-up in this program, but we can at least
     // say that we're here
-    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
     return 0;
   };
@@ -104,7 +104,7 @@ main(int argc, char **argv)
                                     const VectorType &rhs,
                                     VectorType &      dst) -> int {
     deallog << "Solving Jacobian system with rhs=(" << rhs[0] << ',' << rhs[1]
-            << ")" << std::endl;
+            << ')' << std::endl;
 
     // This isn't right for SUNDIALS >4.0: We don't actually get a valid
     // 'u' vector, and so do the linearization of the problem around
diff --git a/tests/sundials/kinsol_03_new_interface.cc b/tests/sundials/kinsol_03_new_interface.cc
index a0d79e3993..b8b6f33b2a 100644
--- a/tests/sundials/kinsol_03_new_interface.cc
+++ b/tests/sundials/kinsol_03_new_interface.cc
@@ -69,7 +69,7 @@ main(int argc, char **argv)
   kinsol.reinit_vector = [N](VectorType &v) { v.reinit(N); };
 
   kinsol.residual = [](const VectorType &u, VectorType &F) -> int {
-    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     F(0) = std::cos(u[0] + u[1]) - 1 + 2 * u[0];
@@ -93,7 +93,7 @@ main(int argc, char **argv)
   kinsol.setup_jacobian = [](const VectorType &u, const VectorType &F) -> int {
     // We don't do any kind of set-up in this program, but we can at least
     // say that we're here
-    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
     return 0;
   };
@@ -103,7 +103,7 @@ main(int argc, char **argv)
                                   VectorType &      dst,
                                   const double /*tolerance*/) -> int {
     deallog << "Solving Jacobian system with rhs=(" << rhs[0] << ',' << rhs[1]
-            << ")" << std::endl;
+            << ')' << std::endl;
 
     // This isn't right for SUNDIALS >4.0: We don't actually get a valid
     // 'u' vector, and so do the linearization of the problem around
diff --git a/tests/sundials/kinsol_04.cc b/tests/sundials/kinsol_04.cc
index b0f079685d..e161e9e5e3 100644
--- a/tests/sundials/kinsol_04.cc
+++ b/tests/sundials/kinsol_04.cc
@@ -81,7 +81,7 @@ main(int argc, char **argv)
   kinsol.reinit_vector = [N](VectorType &v) { v.reinit(N); };
 
   kinsol.residual = [](const VectorType &u, VectorType &F) -> int {
-    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     F(0) = std::cos(u[0] + u[1]) - 1 + 2 * u[0];
@@ -105,7 +105,7 @@ main(int argc, char **argv)
 
   kinsol.setup_jacobian = [&J_inverse](const VectorType &u,
                                        const VectorType &F) -> int {
-    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     FullMatrix<double> J(2, 2);
@@ -125,7 +125,7 @@ main(int argc, char **argv)
                                               const VectorType &rhs,
                                               VectorType &      dst) -> int {
     deallog << "Solving Jacobian system with rhs=(" << rhs[0] << ',' << rhs[1]
-            << ")" << std::endl;
+            << ')' << std::endl;
 
     J_inverse.vmult(dst, rhs);
 
diff --git a/tests/sundials/kinsol_04_new_interface.cc b/tests/sundials/kinsol_04_new_interface.cc
index da932551ed..7d87c063dc 100644
--- a/tests/sundials/kinsol_04_new_interface.cc
+++ b/tests/sundials/kinsol_04_new_interface.cc
@@ -81,7 +81,7 @@ main(int argc, char **argv)
   kinsol.reinit_vector = [N](VectorType &v) { v.reinit(N); };
 
   kinsol.residual = [](const VectorType &u, VectorType &F) -> int {
-    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     F(0) = std::cos(u[0] + u[1]) - 1 + 2 * u[0];
@@ -105,7 +105,7 @@ main(int argc, char **argv)
 
   kinsol.setup_jacobian = [&J_inverse](const VectorType &u,
                                        const VectorType &F) -> int {
-    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     FullMatrix<double> J(2, 2);
@@ -124,7 +124,7 @@ main(int argc, char **argv)
                                             VectorType &      dst,
                                             const double /*tolerance*/) -> int {
     deallog << "Solving Jacobian system with rhs=(" << rhs[0] << ',' << rhs[1]
-            << ")" << std::endl;
+            << ')' << std::endl;
 
     J_inverse.vmult(dst, rhs);
 
diff --git a/tests/sundials/kinsol_05.cc b/tests/sundials/kinsol_05.cc
index a5dfbed054..c32675de7d 100644
--- a/tests/sundials/kinsol_05.cc
+++ b/tests/sundials/kinsol_05.cc
@@ -79,7 +79,7 @@ main(int argc, char **argv)
   kinsol.reinit_vector = [N](VectorType &v) { v.reinit(N); };
 
   kinsol.residual = [](const VectorType &u, VectorType &F) -> int {
-    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     F(0) = std::cos(u[0] + u[1]) - 1 + 2 * u[0];
@@ -105,7 +105,7 @@ main(int argc, char **argv)
                                        const VectorType &F) -> int {
     // We don't do any kind of set-up in this program, but we can at least
     // say that we're here
-    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     FullMatrix<double> J(2, 2);
@@ -125,7 +125,7 @@ main(int argc, char **argv)
                                               const VectorType &rhs,
                                               VectorType &      dst) -> int {
     deallog << "Solving Jacobian system with rhs=(" << rhs[0] << ',' << rhs[1]
-            << ")" << std::endl;
+            << ')' << std::endl;
 
     J_inverse.vmult(dst, rhs);
 
diff --git a/tests/sundials/kinsol_05_new_interface.cc b/tests/sundials/kinsol_05_new_interface.cc
index 4d2e05ecf5..4e9b72a1d1 100644
--- a/tests/sundials/kinsol_05_new_interface.cc
+++ b/tests/sundials/kinsol_05_new_interface.cc
@@ -79,7 +79,7 @@ main(int argc, char **argv)
   kinsol.reinit_vector = [N](VectorType &v) { v.reinit(N); };
 
   kinsol.residual = [](const VectorType &u, VectorType &F) -> int {
-    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Evaluating the solution at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     F(0) = std::cos(u[0] + u[1]) - 1 + 2 * u[0];
@@ -105,7 +105,7 @@ main(int argc, char **argv)
                                        const VectorType &F) -> int {
     // We don't do any kind of set-up in this program, but we can at least
     // say that we're here
-    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ")"
+    deallog << "Setting up Jacobian system at u=(" << u[0] << ',' << u[1] << ')'
             << std::endl;
 
     FullMatrix<double> J(2, 2);
@@ -124,7 +124,7 @@ main(int argc, char **argv)
                                             VectorType &      dst,
                                             const double /*tolerance*/) -> int {
     deallog << "Solving Jacobian system with rhs=(" << rhs[0] << ',' << rhs[1]
-            << ")" << std::endl;
+            << ')' << std::endl;
 
     J_inverse.vmult(dst, rhs);
 
diff --git a/tests/symengine/symengine_tensor_operations_03.cc b/tests/symengine/symengine_tensor_operations_03.cc
index 3b2d40cfd4..4eaf3e4163 100644
--- a/tests/symengine/symengine_tensor_operations_03.cc
+++ b/tests/symengine/symengine_tensor_operations_03.cc
@@ -390,7 +390,7 @@ print(Stream &                          stream,
       const Tensor<1, dim, NumberType> &t)
 {
   for (unsigned int i = 0; i < dim; ++i)
-    stream << name << "[" << i << "]: " << t[i] << std::endl;
+    stream << name << '[' << i << "]: " << t[i] << std::endl;
 }
 template <typename Stream, int dim, typename NumberType>
 void
@@ -400,7 +400,7 @@ print(Stream &                          stream,
 {
   for (unsigned int i = 0; i < dim; ++i)
     for (unsigned int j = 0; j < dim; ++j)
-      stream << name << "[" << i << "][" << j << "]: " << t[i][j] << std::endl;
+      stream << name << '[' << i << "][" << j << "]: " << t[i][j] << std::endl;
 }
 template <typename Stream, int dim, typename NumberType>
 void
@@ -411,7 +411,7 @@ print(Stream &                          stream,
   for (unsigned int i = 0; i < dim; ++i)
     for (unsigned int j = 0; j < dim; ++j)
       for (unsigned int k = 0; k < dim; ++k)
-        stream << name << "[" << i << "][" << j << "][" << k
+        stream << name << '[' << i << "][" << j << "][" << k
                << "]: " << t[i][j][k] << std::endl;
 }
 template <typename Stream, int dim, typename NumberType>
@@ -424,7 +424,7 @@ print(Stream &                          stream,
     for (unsigned int j = 0; j < dim; ++j)
       for (unsigned int k = 0; k < dim; ++k)
         for (unsigned int l = 0; l < dim; ++l)
-          stream << name << "[" << i << "][" << j << "][" << k << "][" << l
+          stream << name << '[' << i << "][" << j << "][" << k << "][" << l
                  << "]: " << t[i][j][k][l] << std::endl;
 }
 
diff --git a/tests/tensors/constexpr_tensor.cc b/tests/tensors/constexpr_tensor.cc
index 89634f375a..19684dc2da 100644
--- a/tests/tensors/constexpr_tensor.cc
+++ b/tests/tensors/constexpr_tensor.cc
@@ -26,7 +26,7 @@ test_constexpr_tensor_constructors()
   constexpr dealii::Tensor<rank, dim, Number> a;
   constexpr dealii::Tensor<rank, dim, Number> b(a);
   constexpr dealii::Tensor<rank, dim, Number> c = a;
-  deallog << " Tensor<" << rank << "," << dim << ">" << std::endl;
+  deallog << " Tensor<" << rank << ',' << dim << '>' << std::endl;
   deallog << a << std::endl;
   deallog << b << std::endl;
   deallog << c << std::endl;
diff --git a/tests/tensors/symmetric_tensor_28.cc b/tests/tensors/symmetric_tensor_28.cc
index 7dd9f8181b..693f8f09fc 100644
--- a/tests/tensors/symmetric_tensor_28.cc
+++ b/tests/tensors/symmetric_tensor_28.cc
@@ -38,8 +38,8 @@ test()
 
   for (unsigned int i = 0; i < dim; ++i)
     for (unsigned int j = 0; j < dim; ++j)
-      deallog << (i + 1) * (j + 1) << " " << (int)s[i][j] << " " << (int)t[i][j]
-              << " " << (int)u[i][j] << std::endl;
+      deallog << (i + 1) * (j + 1) << ' ' << (int)s[i][j] << ' ' << (int)t[i][j]
+              << ' ' << (int)u[i][j] << std::endl;
 }
 
 
diff --git a/tests/tensors/symmetric_tensor_36.cc b/tests/tensors/symmetric_tensor_36.cc
index dad3efed69..ad49eba312 100644
--- a/tests/tensors/symmetric_tensor_36.cc
+++ b/tests/tensors/symmetric_tensor_36.cc
@@ -50,8 +50,8 @@ typename std::enable_if<std::is_constructible<NumberType1, NumberType2>::value,
 test_tensor_constructor(const std::string &type1, const std::string &type2)
 {
   deallog << "Rank " << rank << ", "
-          << "Dim " << dim << ":"
-          << "  From " << type2 << " To " << type1 << " ... " << std::flush;
+          << "Dim " << dim << ':' << "  From " << type2 << " To " << type1
+          << " ... " << std::flush;
   TensorType<rank, dim, NumberType2> tmp2;
   TensorType<rank, dim, NumberType1> tmp1(tmp2);
   deallog << "OK" << std::endl;
diff --git a/tests/tensors/tensor_accessors_01.cc b/tests/tensors/tensor_accessors_01.cc
index 762fa4bcba..c00578566f 100644
--- a/tests/tensors/tensor_accessors_01.cc
+++ b/tests/tensors/tensor_accessors_01.cc
@@ -22,7 +22,7 @@
   for (unsigned int i = 0; i < 2; ++i)     \
     for (unsigned int j = 0; j < 2; ++j)   \
       for (unsigned int k = 0; k < 2; ++k) \
-        deallog << bar[i][j][k] << " ";    \
+        deallog << bar[i][j][k] << ' ';    \
   deallog << std::endl;
 
 
diff --git a/tests/tensors/tensor_accessors_03.cc b/tests/tensors/tensor_accessors_03.cc
index ff5b85b457..038e387a1e 100644
--- a/tests/tensors/tensor_accessors_03.cc
+++ b/tests/tensors/tensor_accessors_03.cc
@@ -83,7 +83,7 @@ main()
     //     for (unsigned int k = 0; k < 4; ++k)
     //       for (unsigned int l = 0; l < 4; ++l)
     //         {
-    //           deallog << "(" << i << "," << j << "," << k << "," << l << "):
+    //           deallog << '(' << i << ',' << j << ',' << k << ',' << l << "):
     //           "; deallog << result[i][j][k][l] << " = " << left2[i][j] << " *
     //           " << right2[k][l] << std::endl;
     //         }
diff --git a/tests/trilinos/add_matrices_05.cc b/tests/trilinos/add_matrices_05.cc
index 792f22d533..028caca0b6 100644
--- a/tests/trilinos/add_matrices_05.cc
+++ b/tests/trilinos/add_matrices_05.cc
@@ -46,7 +46,7 @@ test(TrilinosWrappers::SparseMatrix &m)
   m.compress(VectorOperation::insert);
   m2.compress(VectorOperation::insert);
 
-  deallog << "Matrix nonzeros: " << m.n_nonzero_elements() << " "
+  deallog << "Matrix nonzeros: " << m.n_nonzero_elements() << ' '
           << m2.n_nonzero_elements() << std::endl;
 
   m.print(deallog.get_file_stream());
diff --git a/tests/trilinos/add_matrices_06.cc b/tests/trilinos/add_matrices_06.cc
index 2d467f2872..becb59d30f 100644
--- a/tests/trilinos/add_matrices_06.cc
+++ b/tests/trilinos/add_matrices_06.cc
@@ -49,8 +49,8 @@ test(TrilinosWrappers::SparseMatrix &m)
   m2.compress(VectorOperation::insert);
   m3.compress(VectorOperation::insert);
 
-  deallog << "Matrix nonzeros: " << m.n_nonzero_elements() << " "
-          << m2.n_nonzero_elements() << " " << m3.n_nonzero_elements()
+  deallog << "Matrix nonzeros: " << m.n_nonzero_elements() << ' '
+          << m2.n_nonzero_elements() << ' ' << m3.n_nonzero_elements()
           << std::endl;
 
   m.copy_from(m2);
@@ -63,7 +63,7 @@ test(TrilinosWrappers::SparseMatrix &m)
   prec.initialize(m);
 
   m.vmult(dst, src);
-  deallog << "Vector norm: " << dst.l2_norm() << " ";
+  deallog << "Vector norm: " << dst.l2_norm() << ' ';
 
   prec.vmult(dst, src);
   deallog << dst.l2_norm() << std::endl;
@@ -72,7 +72,7 @@ test(TrilinosWrappers::SparseMatrix &m)
   m.add(0.06, m3);
 
   m.vmult(dst, src);
-  deallog << "Vector norm: " << dst.l2_norm() << " ";
+  deallog << "Vector norm: " << dst.l2_norm() << ' ';
 
   prec.vmult(dst, src);
   deallog << dst.l2_norm() << std::endl;
diff --git a/tests/trilinos/block_vector_move_operations.cc b/tests/trilinos/block_vector_move_operations.cc
index 2a4ad6916f..ad25952c20 100644
--- a/tests/trilinos/block_vector_move_operations.cc
+++ b/tests/trilinos/block_vector_move_operations.cc
@@ -20,12 +20,12 @@
 #include "../tests.h"
 
 #define PRINTBLOCK(name, var)                                \
-  deallog << "Block vector: " name << ":" << std::endl;      \
+  deallog << "Block vector: " name << ':' << std::endl;      \
   for (unsigned int i = 0; i < var.n_blocks(); ++i)          \
     {                                                        \
       deallog << "[block " << i << " ]  ";                   \
       for (unsigned int j = 0; j < var.block(i).size(); ++j) \
-        deallog << var.block(i)[j] << " ";                   \
+        deallog << var.block(i)[j] << ' ';                   \
       deallog << std::endl;                                  \
     }
 
diff --git a/tests/trilinos/copy_to_dealvec_block.cc b/tests/trilinos/copy_to_dealvec_block.cc
index c197e5f3ac..6558705338 100644
--- a/tests/trilinos/copy_to_dealvec_block.cc
+++ b/tests/trilinos/copy_to_dealvec_block.cc
@@ -82,8 +82,8 @@ test()
   // check local values
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
     {
-      deallog << myid * 2 << ":" << copied(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << copied(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << copied(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << copied(myid * 2 + 1) << std::endl;
     }
 
   for (unsigned int bl = 0; bl < 2; ++bl)
@@ -104,8 +104,8 @@ test()
   // check local values
   if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
     {
-      deallog << myid * 2 << ":" << copied(myid * 2) << std::endl;
-      deallog << myid * 2 + 1 << ":" << copied(myid * 2 + 1) << std::endl;
+      deallog << myid * 2 << ':' << copied(myid * 2) << std::endl;
+      deallog << myid * 2 + 1 << ':' << copied(myid * 2 + 1) << std::endl;
     }
 
   for (unsigned int bl = 0; bl < 2; ++bl)
diff --git a/tests/trilinos/sparsity_pattern_06.cc b/tests/trilinos/sparsity_pattern_06.cc
index d4200b25ce..745946e5c3 100644
--- a/tests/trilinos/sparsity_pattern_06.cc
+++ b/tests/trilinos/sparsity_pattern_06.cc
@@ -66,8 +66,8 @@ test()
 
   for (const auto &el : sp)
     {
-      deallog << "index: " << el.index() << " = "
-              << "(" << el.row() << " , " << el.column() << ")" << std::endl;
+      deallog << "index: " << el.index() << " = " << '(' << el.row() << " , "
+              << el.column() << ')' << std::endl;
     }
 
   sp.compress();
@@ -75,8 +75,8 @@ test()
   deallog << "after compress:" << std::endl;
   for (const auto &el : sp)
     {
-      deallog << "index: " << el.index() << " = "
-              << "(" << el.row() << " , " << el.column() << ")" << std::endl;
+      deallog << "index: " << el.index() << " = " << '(' << el.row() << " , "
+              << el.column() << ')' << std::endl;
     }
 }
 
diff --git a/tests/trilinos/vector_move_operations.cc b/tests/trilinos/vector_move_operations.cc
index 4673f7e179..76cbd26bad 100644
--- a/tests/trilinos/vector_move_operations.cc
+++ b/tests/trilinos/vector_move_operations.cc
@@ -20,9 +20,9 @@
 #include "../tests.h"
 
 #define PRINTME(name, var)                        \
-  deallog << "Vector: " name << ":" << std::endl; \
+  deallog << "Vector: " name << ':' << std::endl; \
   for (unsigned int i = 0; i < var.size(); ++i)   \
-    deallog << var[i] << " ";                     \
+    deallog << var[i] << ' ';                     \
   deallog << std::endl;
 
 int
diff --git a/tests/zoltan/zoltan_02.cc b/tests/zoltan/zoltan_02.cc
index 21631cc04d..7c50832f07 100644
--- a/tests/zoltan/zoltan_02.cc
+++ b/tests/zoltan/zoltan_02.cc
@@ -78,6 +78,6 @@ main(int argc, char **argv)
   deallog << "Number of colors used: " << num_colors << std::endl;
   for (unsigned int i = 0; i < num_indices; ++i)
     {
-      deallog << i << " " << color_indices[i] << std::endl;
+      deallog << i << ' ' << color_indices[i] << std::endl;
     }
 }
diff --git a/tests/zoltan/zoltan_03.cc b/tests/zoltan/zoltan_03.cc
index 17f073a4cc..466e31fd10 100644
--- a/tests/zoltan/zoltan_03.cc
+++ b/tests/zoltan/zoltan_03.cc
@@ -79,6 +79,6 @@ main(int argc, char **argv)
   deallog << "Number of colors used: " << num_colors << std::endl;
   for (unsigned int i = 0; i < num_indices; ++i)
     {
-      deallog << i << " " << color_indices[i] << std::endl;
+      deallog << i << ' ' << color_indices[i] << std::endl;
     }
 }
diff --git a/tests/zoltan/zoltan_04.cc b/tests/zoltan/zoltan_04.cc
index a68b0c91cb..ae23afe3e9 100644
--- a/tests/zoltan/zoltan_04.cc
+++ b/tests/zoltan/zoltan_04.cc
@@ -72,6 +72,6 @@ main(int argc, char **argv)
   deallog << "Number of colors used: " << num_colors << std::endl;
   for (unsigned int i = 0; i < num_indices; ++i)
     {
-      deallog << i << " " << color_indices[i] << std::endl;
+      deallog << i << ' ' << color_indices[i] << std::endl;
     }
 }
-- 
2.39.5