--- /dev/null
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2018 - 2021 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.
+//
+// ---------------------------------------------------------------------
+
+
+// Set up a two cells with different elements, such that neither element
+// dominates. Create an FEInterfaceValues object and call reinit on it.
+//
+// In this test case, there is are two quadrature objects, but they
+// are identical, so again it does not matter.
+
+#include <deal.II/base/quadrature_lib.h>
+
+#include <deal.II/fe/fe_interface_values.h>
+#include <deal.II/fe/fe_q.h>
+#include <deal.II/fe/fe_system.h>
+
+#include <deal.II/grid/grid_generator.h>
+#include <deal.II/grid/tria.h>
+
+#include "../tests.h"
+
+template <int dim>
+void
+make_2_cells(Triangulation<dim> &tria);
+
+template <>
+void
+make_2_cells<2>(Triangulation<2> &tria)
+{
+ const unsigned int dim = 2;
+ std::vector<unsigned int> repetitions = {2, 1};
+ Point<dim> p1;
+ Point<dim> p2(2.0, 1.0);
+
+ GridGenerator::subdivided_hyper_rectangle(tria, repetitions, p1, p2);
+}
+
+
+template <int dim>
+void
+test()
+{
+ Triangulation<dim> tria;
+ make_2_cells(tria);
+
+ const unsigned max_fe_degree = 2;
+ const FESystem<dim> fe_left(FE_Q<dim>(1), FE_Q<dim>(2));
+ const FESystem<dim> fe_right(FE_Q<dim>(2), FE_Q<dim>(1));
+
+ hp::FECollection<dim> fe_collection;
+ fe_collection.push_back(fe_left);
+ fe_collection.push_back(fe_right);
+
+ DoFHandler<dim> dofh(tria);
+
+ const unsigned int face_index = 1;
+
+ auto cell = dofh.begin();
+ auto neighbor = cell->neighbor(face_index);
+
+ cell->set_active_fe_index(0);
+ neighbor->set_active_fe_index(1);
+
+ dofh.distribute_dofs(fe_collection);
+
+ const QGauss<dim - 1> quadrature(max_fe_degree + 1);
+ const hp::QCollection<dim - 1> q_collection(quadrature, quadrature);
+
+ const MappingQ<dim> mapping(1);
+ const hp::MappingCollection<dim> mapping_collection(mapping);
+
+
+ deallog << "Adjacent finite elements: " << cell->get_fe().get_name()
+ << " and " << neighbor->get_fe().get_name() << std::endl;
+
+ const UpdateFlags update_flags = update_values;
+ FEInterfaceValues<dim> fiv(mapping_collection,
+ fe_collection,
+ q_collection,
+ update_flags);
+ fiv.reinit(cell,
+ face_index,
+ /* subface_no */ numbers::invalid_unsigned_int,
+ neighbor,
+ cell->neighbor_of_neighbor(face_index),
+ /* subface_no_neighbor */ numbers::invalid_unsigned_int,
+ /* q_index */ numbers::invalid_unsigned_int,
+ /* mapping_index */ numbers::invalid_unsigned_int,
+ /* fe_index */ numbers::invalid_unsigned_int);
+
+ deallog << "Chosen quadrature for the common face has "
+ << fiv.get_fe_face_values(0).get_quadrature().size()
+ << " quadrature points. These points are located at:" << std::endl;
+ for (const auto p : fiv.get_fe_face_values(0).get_quadrature().get_points())
+ deallog << " " << p << std::endl;
+
+ // Also check that we see the same quadrature formula from both
+ // sides:
+ Assert(fiv.get_fe_face_values(0).get_quadrature().get_points() ==
+ fiv.get_fe_face_values(1).get_quadrature().get_points(),
+ ExcInternalError());
+
+ deallog << "OK" << std::endl;
+}
+
+
+
+int
+main()
+{
+ initlog();
+ test<2>();
+}