Test ghost for forests with holes

test/Makefile.am

@@ -42,6 +42,7 @@ t8code_googletest_programs = \
   test/t8_forest/t8_gtest_user_data \
   test/t8_forest/t8_gtest_transform \
   test/t8_forest/t8_gtest_ghost_exchange \
+  test/t8_forest/t8_gtest_ghost_delete \
   test/t8_forest/t8_gtest_ghost_and_owner \
   test/t8_IO/t8_gtest_vtk_reader \
   test/t8_forest_incomplete/t8_gtest_permute_hole \
@@ -210,6 +211,10 @@ test_t8_forest_t8_gtest_ghost_exchange_SOURCES = \
   test/t8_gtest_main.cxx \
   test/t8_forest/t8_gtest_ghost_exchange.cxx
 
+test_t8_forest_t8_gtest_ghost_delete_SOURCES = \
+  test/t8_gtest_main.cxx \
+  test/t8_forest/t8_gtest_ghost_delete.cxx
+
 test_t8_forest_t8_gtest_ghost_and_owner_SOURCES = \
   test/t8_gtest_main.cxx \
   test/t8_forest/t8_gtest_ghost_and_owner.cxx
@@ -399,6 +404,10 @@ test_t8_forest_t8_gtest_ghost_exchange_LDADD = $(t8_gtest_target_ld_add)
 test_t8_forest_t8_gtest_ghost_exchange_LDFLAGS = $(t8_gtest_target_ld_flags)
 test_t8_forest_t8_gtest_ghost_exchange_CPPFLAGS = $(t8_gtest_target_cpp_flags)
 
+test_t8_forest_t8_gtest_ghost_delete_LDADD = $(t8_gtest_target_ld_add)
+test_t8_forest_t8_gtest_ghost_delete_LDFLAGS = $(t8_gtest_target_ld_flags)
+test_t8_forest_t8_gtest_ghost_delete_CPPFLAGS = $(t8_gtest_target_cpp_flags)
+
 test_t8_forest_t8_gtest_ghost_and_owner_LDADD = $(t8_gtest_target_ld_add)
 test_t8_forest_t8_gtest_ghost_and_owner_LDFLAGS = $(t8_gtest_target_ld_flags)
 test_t8_forest_t8_gtest_ghost_and_owner_CPPFLAGS = $(t8_gtest_target_cpp_flags)
@@ -469,6 +478,7 @@ test_t8_geometry_t8_gtest_point_inside_CPPFLAGS += $(t8_gtest_target_mpi_cpp_fla
 test_t8_forest_t8_gtest_user_data_CPPFLAGS += $(t8_gtest_target_mpi_cpp_flags)
 test_t8_forest_t8_gtest_transform_CPPFLAGS += $(t8_gtest_target_mpi_cpp_flags)
 test_t8_forest_t8_gtest_ghost_exchange_CPPFLAGS += $(t8_gtest_target_mpi_cpp_flags)
+test_t8_forest_t8_gtest_ghost_delete_CPPFLAGS += $(t8_gtest_target_mpi_cpp_flags)
 test_t8_forest_t8_gtest_ghost_and_owner_CPPFLAGS += $(t8_gtest_target_mpi_cpp_flags)
 test_t8_IO_t8_gtest_vtk_reader_CPPFLAGS += $(t8_gtest_target_mpi_cpp_flags)
 test_t8_forest_incomplete_t8_gtest_permute_hole_CPPFLAGS += $(t8_gtest_target_mpi_cpp_flags)

test/t8_forest/t8_gtest_ghost_delete.cxx

@@ -0,0 +1,120 @@
+/*
+  This file is part of t8code.
+  t8code is a C library to manage a collection (a forest) of multiple
+  connected adaptive space-trees of general element classes in parallel.
+
+  Copyright (C) 2015 the developers
+
+  t8code is free software; you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation; either version 2 of the License, or
+  (at your option) any later version.
+
+  t8code is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with t8code; if not, write to the Free Software Foundation, Inc.,
+  51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+*/
+
+#include <gtest/gtest.h>
+#include <t8_eclass.h>
+#include <t8_schemes/t8_default/t8_default_cxx.hxx>
+#include <t8_forest/t8_forest_general.h>
+#include <t8_forest/t8_forest_geometrical.h>
+#include <t8_forest/t8_forest_ghost.h>
+#include <t8_forest/t8_forest_private.h>
+#include <t8_cmesh.h>
+#include <t8_cmesh/t8_cmesh_examples.h>
+
+/* This test is executed on a subcommunicator of exactly 2 procs, because it demonstrates a configuration that is currently not working
+ * A partitioned square of uniform refinement level 1 is adapted once, where only the lower half is refined.
+ * Then the mesh is adapted again, where only the upper half of the lower elements is deleted.
+ * Now, no element actually has a face connection to an existing element on the other proc, but they send a message anyway.
+ */
+
+
+/* refine elements, whose y coordinate is 0, so that the lowest row is refined
+ * delete elements, whose y coordniate is 0.25, so that the second row is deleted
+ */
+static int
+test_adapt_holes (t8_forest_t forest, t8_forest_t forest_from, t8_locidx_t which_tree, t8_locidx_t lelement_id,
+                  t8_eclass_scheme_c *ts, const int is_family, const int num_elements, t8_element_t *elements[])
+{
+  double coordinates[3];
+  t8_forest_element_coordinate (forest_from, which_tree, elements[0], 0, coordinates);
+  if (fabs (coordinates[1]) < T8_PRECISION_EPS)
+    return 1;  // refine the lowest row
+  if (fabs (coordinates[1] - 0.25) < T8_PRECISION_EPS)
+    return -2;  // delete the higher row in the lower quadrants
+  return 0;
+}
+
+class forest_ghost_exchange_holes: public testing::Test {
+ protected:
+  void
+  SetUp () override
+  {
+    /* adjust communicator size, we split the comm here, because we know that the test fails on 2 procs*/
+    int size, rank, color, key;
+
+    sc_MPI_Comm_size (sc_MPI_COMM_WORLD, &size);
+    sc_MPI_Comm_rank (sc_MPI_COMM_WORLD, &rank);
+
+    if (rank < 2) {
+      color = 0;
+      key = rank;
+    }
+    else {
+      color = sc_MPI_UNDEFINED;
+      key = -1;
+    }
+    sc_MPI_Comm_split (sc_MPI_COMM_WORLD, color, key, &comm);
+    T8_ASSERT (rank < 2 || comm == sc_MPI_COMM_NULL);
+
+    if (comm != sc_MPI_COMM_NULL) {
+      sc_MPI_Comm_size (comm, &size);
+      T8_ASSERT(size <= 2);
+      scheme = t8_scheme_new_default_cxx ();
+      /* Construct a cmesh */
+      cmesh = t8_cmesh_new_hypercube (T8_ECLASS_QUAD, comm, 0, 0, 0);
+    }else{
+      T8_ASSERT(rank >= 2);
+    }
+  }
+  void
+  TearDown () override
+  {
+    //cmesh and scheme are freed taken and freed by forest
+    if (comm != sc_MPI_COMM_NULL) {
+      sc_MPI_Comm_free (&comm);
+    }
+    sc_MPI_Barrier (sc_MPI_COMM_WORLD);
+    t8_cmesh_unref (&cmesh);
+    t8_scheme_cxx_unref (&scheme);
+  }
+  sc_MPI_Comm comm;
+  t8_scheme_cxx_t *scheme;
+  t8_cmesh_t cmesh;
+};
+
+TEST_F (forest_ghost_exchange_holes, errorTest)
+{
+  /* This test tests the functionality described in Issue: https://github.com/DLR-AMR/t8code/issues/825
+  * Remove the GTEST_SKIP() macros when you start working on the issue.
+  */
+  GTEST_SKIP(); 
+  if (comm != sc_MPI_COMM_NULL) {
+    const int level = 1;
+    const int execute_ghost = 1;
+    t8_cmesh_ref(cmesh);
+    t8_scheme_cxx_ref(scheme);
+    t8_forest_t forest = t8_forest_new_uniform (cmesh, scheme, level, 1, comm);
+    forest = t8_forest_new_adapt (forest, test_adapt_holes, 0, execute_ghost, NULL);
+    forest = t8_forest_new_adapt (forest, test_adapt_holes, 0, execute_ghost, NULL);
+    t8_forest_unref (&forest);
+  }
+}