From 791d6428c8d62f3e3f218e6bfcd84b529805137a Mon Sep 17 00:00:00 2001
From: Timo Heister <timo.heister@gmail.com>
Date: Sun, 8 Aug 2021 17:40:48 -0400
Subject: [PATCH] add broken test

---
 tests/multigrid/transfer_matrix_free_14.cc    | 94 +++++++++++++++++++
 ...ix_free_14.with_p4est=true.mpirun=2.output | 19 ++++
 2 files changed, 113 insertions(+)
 create mode 100644 tests/multigrid/transfer_matrix_free_14.cc
 create mode 100644 tests/multigrid/transfer_matrix_free_14.with_p4est=true.mpirun=2.output

diff --git a/tests/multigrid/transfer_matrix_free_14.cc b/tests/multigrid/transfer_matrix_free_14.cc
new file mode 100644
index 0000000000..e683c5e67a
--- /dev/null
+++ b/tests/multigrid/transfer_matrix_free_14.cc
@@ -0,0 +1,94 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2016 - 2020 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+
+// document a bug in MGLevelGlobalTransfer in 3d:
+
+/*
+An error occurred in line <341> of file
+<../source/multigrid/mg_level_global_transfer.cc> in function void
+dealii::MGLevelGlobalTransfer<dealii::LinearAlgebra::distributed::Vector<Number,
+dealii::MemorySpace::Host> >::fill_and_communicate_copy_indices(const
+dealii::DoFHandler<dh_dim, spacedim>&) [with int dim = 3; int spacedim = 3;
+Number = double] The violated condition was:
+    ::dealii::deal_II_exceptions::internals::compare_for_equality(this->copy_indices_level_mine.back().n_rows(),
+0) Additional information: Dimension 2 not equal to 0.
+*/
+
+#include <deal.II/distributed/tria.h>
+
+#include <deal.II/fe/fe_q.h>
+
+#include <deal.II/grid/grid_generator.h>
+
+#include <deal.II/multigrid/mg_transfer.h>
+#include <deal.II/multigrid/mg_transfer_matrix_free.h>
+
+#include "../tests.h"
+
+template <int dim>
+void
+check()
+{
+  parallel::distributed::Triangulation<dim> tr(
+    MPI_COMM_WORLD,
+    Triangulation<dim>::limit_level_difference_at_vertices,
+    typename parallel::distributed::Triangulation<dim>::Settings(
+      parallel::distributed::Triangulation<
+        dim>::mesh_reconstruction_after_repartitioning |
+      parallel::distributed::Triangulation<
+        dim>::construct_multigrid_hierarchy));
+
+  GridGenerator::hyper_cube(tr);
+
+  tr.refine_global(2);
+
+  // coarsen a few cells:
+  for (const auto &cell : tr.active_cell_iterators())
+    {
+      if (cell->is_artificial())
+        continue;
+      const std::string id = cell->parent()->id().to_string();
+      if (id == "0_1:0" || id == "0_1:1" || id == "0_1:2" || id == "0_1:3")
+        cell->set_coarsen_flag();
+    }
+
+  tr.execute_coarsening_and_refinement();
+
+  FE_Q<dim>                         fe(1);
+  DoFHandler<dim>                   mgdof(tr);
+  MGTransferMatrixFree<dim, double> transfer_mf;
+
+  mgdof.distribute_dofs(fe);
+  mgdof.distribute_mg_dofs();
+
+  deallog << "n_dofs = " << mgdof.n_dofs() << std::endl;
+
+  transfer_mf.build(mgdof);
+
+  tr.coarsen_global();
+  deallog << "OK" << std::endl;
+}
+
+
+int
+main(int argc, char **argv)
+{
+  Utilities::MPI::MPI_InitFinalize mpi(argc, argv, 1);
+  MPILogInitAll                    all;
+
+  check<2>();
+  check<3>();
+}
diff --git a/tests/multigrid/transfer_matrix_free_14.with_p4est=true.mpirun=2.output b/tests/multigrid/transfer_matrix_free_14.with_p4est=true.mpirun=2.output
new file mode 100644
index 0000000000..ee2f46465a
--- /dev/null
+++ b/tests/multigrid/transfer_matrix_free_14.with_p4est=true.mpirun=2.output
@@ -0,0 +1,19 @@
+
+DEAL::n_dofs = 50
+DEAL::OK
+DEAL::n_dofs = 18
+DEAL::OK
+DEAL::n_dofs = 8
+DEAL::OK
+DEAL::n_dofs = 8
+DEAL::OK
+DEAL::
+DEAL::n_dofs = 375
+DEAL::OK
+DEAL::n_dofs = 81
+DEAL::OK
+DEAL::n_dofs = 24
+DEAL::OK
+DEAL::n_dofs = 24
+DEAL::OK
+DEAL::
-- 
2.39.5