--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2016 - 2018 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.
+//
+// ---------------------------------------------------------------------
+
+
+// Like the data_out_faces_postprocess_boundary_id_02 test, but also
+// output information about internal faces (with -1 to indicate that
+// no boundary indicator is available).
+
+
+#include <deal.II/base/function.h>
+
+#include <deal.II/dofs/dof_accessor.h>
+#include <deal.II/dofs/dof_handler.h>
+
+#include <deal.II/fe/fe_dgq.h>
+#include <deal.II/fe/fe_system.h>
+
+#include <deal.II/grid/grid_generator.h>
+#include <deal.II/grid/tria.h>
+#include <deal.II/grid/tria_accessor.h>
+#include <deal.II/grid/tria_iterator.h>
+
+#include <deal.II/lac/vector.h>
+
+#include <deal.II/numerics/data_out_faces.h>
+#include <deal.II/numerics/data_postprocessor.h>
+#include <deal.II/numerics/matrix_tools.h>
+#include <deal.II/numerics/vector_tools.h>
+
+#include "../tests.h"
+
+
+
+std::ofstream logfile("output");
+
+
+template <int dim>
+void
+test()
+{
+ Triangulation<dim> triangulation;
+ FE_DGQ<dim> fe(1);
+ DoFHandler<dim> dof_handler(triangulation);
+
+ GridGenerator::hyper_cube(triangulation, 0, 1, true);
+ triangulation.refine_global(1);
+ triangulation.begin_active()->set_refine_flag();
+ triangulation.execute_coarsening_and_refinement();
+
+ dof_handler.distribute_dofs(fe);
+
+ // Create a dummy vector. We will ignore its contents.
+ Vector<double> solution(dof_handler.n_dofs());
+
+ DataPostprocessors::BoundaryIds<dim> p;
+ DataOutFaces<dim> data_out(false);
+ data_out.attach_dof_handler(dof_handler);
+ data_out.add_data_vector(solution, p);
+ data_out.build_patches();
+ data_out.write_gnuplot(logfile);
+}
+
+
+int
+main()
+{
+ logfile << std::setprecision(2);
+ deallog << std::setprecision(2);
+
+ test<2>();
+ test<2>();
+
+ return 0;
+}