Add a test.

diff --git a/tests/data_out/data_out_faces_postprocessor_boundary_id.cc b/tests/data_out/data_out_faces_postprocessor_boundary_id.cc
new file mode 100644 (file)
index 0000000..404cc26
--- /dev/null
+++ b/tests/data_out/data_out_faces_postprocessor_boundary_id.cc
@@ -0,0 +1,118 @@
+// ---------------------------------------------------------------------
+//
+// 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.
+//
+// ---------------------------------------------------------------------
+
+
+// Tests DataPostprocessor: access the cell and face we are currently
+// working on for a scalar finite element field and DataOutFaces. This
+// is then used to output the boundary id of a face.
+
+
+#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>
+class BoundaryIds : public DataPostprocessorScalar<dim>
+{
+public:
+  BoundaryIds()
+    : DataPostprocessorScalar<dim>("boundary_id", update_quadrature_points)
+  {}
+
+
+  virtual void
+  evaluate_scalar_field(
+    const DataPostprocessorInputs::Scalar<dim> &inputs,
+    std::vector<Vector<double>> &computed_quantities) const override
+  {
+    AssertDimension(computed_quantities.size(), inputs.solution_values.size());
+
+    // Get the cell and face we are currently dealing with:
+    const typename DoFHandler<dim>::active_cell_iterator cell =
+      inputs.template get_cell<dim>();
+    const unsigned int face = inputs.get_face_number();
+
+    // Then fill the output fields with the boundary_id of the face
+    for (auto &output : computed_quantities)
+      {
+        AssertDimension(output.size(), 1);
+        output(0) = cell->face(face)->boundary_id();
+      }
+  }
+};
+
+
+
+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());
+
+  BoundaryIds<dim>  p;
+  DataOutFaces<dim> data_out;
+  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;
+}

diff --git a/tests/data_out/data_out_faces_postprocessor_boundary_id.output b/tests/data_out/data_out_faces_postprocessor_boundary_id.output
new file mode 100644 (file)
index 0000000..60c706e
--- /dev/null
+++ b/tests/data_out/data_out_faces_postprocessor_boundary_id.output
@@ -0,0 +1,94 @@
+# This file was generated by the deal.II library.
+
+
+#
+# For a description of the GNUPLOT format see the GNUPLOT manual.
+#
+# <x> <y> <boundary_id> 
+1 0 1 
+1 0.5 1 
+
+
+0.5 0 2 
+1 0 2 
+
+
+0 0.5 0 
+0 1 0 
+
+
+0 1 3 
+0.5 1 3 
+
+
+1 0.5 1 
+1 1 1 
+
+
+0.5 1 3 
+1 1 3 
+
+
+0 0 0 
+0 0.25 0 
+
+
+0 0 2 
+0.25 0 2 
+
+
+0.25 0 2 
+0.5 0 2 
+
+
+0 0.25 0 
+0 0.5 0 
+
+
+# This file was generated by the deal.II library.
+
+
+#
+# For a description of the GNUPLOT format see the GNUPLOT manual.
+#
+# <x> <y> <boundary_id> 
+1 0 1 
+1 0.5 1 
+
+
+0.5 0 2 
+1 0 2 
+
+
+0 0.5 0 
+0 1 0 
+
+
+0 1 3 
+0.5 1 3 
+
+
+1 0.5 1 
+1 1 1 
+
+
+0.5 1 3 
+1 1 3 
+
+
+0 0 0 
+0 0.25 0 
+
+
+0 0 2 
+0.25 0 2 
+
+
+0.25 0 2 
+0.5 0 2 
+
+
+0 0.25 0 
+0 0.5 0 
+
+