Fix bug when fractal surfaces at an MPI boundary

- Add a new test that better tests this scenario

reframe_tests/tests/src/geometry_tests/add_surface_roughness_geometry/add_surface_roughness_boundaries.in

@@ -0,0 +1,19 @@
+#title: Heterogeneous soil using a stochastic distribution of dielectric properties given by a mixing model from Peplinski
+#domain: 0.100 0.100 0.100
+#dx_dy_dz: 0.001 0.001 0.001
+#time_window: 3e-9
+
+#waveform: ricker 1 1.5e9 my_ricker
+#hertzian_dipole: y 0.02 0.02 0.02 my_ricker
+#rx: 0.080 0.080 0.080
+
+#soil_peplinski: 0.5 0.5 2.0 2.66 0.001 0.25 my_soil
+
+#fractal_box: 0 0 0 0.049 0.05 0.051 1.5 1 1 1 50 my_soil box_1 42
+#fractal_box: 0.049 0.05 0.051 0.1 0.1 0.1 1.5 1 1 1 50 my_soil box_2 22
+
+#add_surface_roughness: 0.049 0 0 0.049 0.05 0.05 1 1 1 0.025 0.05 box_1 43
+#add_surface_roughness: 0.049 0.05 0.051 0.049 0.1 0.1 1 1 1 0.049 0.074 box_2 23
+
+
+#geometry_objects_write: 0 0 0 0.1 0.1 0.1 full_volume

reframe_tests/tests/test_geometry.py

@@ -25,6 +25,7 @@ class TestAddSurfaceRoughness(GprMaxGeometryTest):
             "add_surface_roughness_half",
             "add_surface_roughness_small",
             "add_surface_roughness_weighted",
+            "add_surface_roughness_boundaries",
         ]
     )
 
@@ -166,17 +167,60 @@ class TestTriangleGeometry(GprMaxRegressionTest):
 
 
 @rfm.simple_test
-class TestAddGrassMpi(TestAddGrass):
+class TestAddGrassMpi(MpiMixin, TestAddGrass):
     tags = {"test", "mpi", "geometery", "fractal", "surface", "grass"}
     mpi_layout = parameter([[1, 2, 2], [3, 1, 3], [4, 1, 4]])
     test_dependency = TestAddGrass
 
 
+# Depending on the orientation/alignment of the fractal surface, not all
+# MPI decompositions are valid. Therefore create tests that divide the
+# domain in each pair of dimensions.
+# NB: The 'add_surface_roughness_half' test currently fails due to the
+# floating point precision of the fractal surface. Caused by the:
+# if (k < surface.fractalsurface[i - surface.xs, j - surface.ys]):
+# checks in gprMax/user_objects/cmds_geometry/fractal_box.py
 @rfm.simple_test
-class TestAddSurfaceRoughnessMpi(MpiMixin, TestAddSurfaceRoughness):
+class TestAddSurfaceRoughnessMpiYZ(MpiMixin, TestAddSurfaceRoughness):
     tags = {"test", "mpi", "geometery", "fractal", "surface", "roughness"}
-    mpi_layout = parameter([[2, 1, 2], [3, 3, 1], [1, 4, 4]])
+    mpi_layout = parameter([[1, 2, 2], [1, 3, 3], [1, 4, 4]])
     test_dependency = TestAddSurfaceRoughness
+    model = parameter(
+        [
+            "add_surface_roughness_full",
+            # "add_surface_roughness_half",
+            "add_surface_roughness_small",
+            "add_surface_roughness_weighted",
+        ]
+    )
+
+
+@rfm.simple_test
+class TestAddSurfaceRoughnessMpiXZ(MpiMixin, TestAddSurfaceRoughness):
+    tags = {"test", "mpi", "geometery", "fractal", "surface", "roughness"}
+    mpi_layout = parameter([[2, 1, 2], [3, 1, 3], [4, 1, 4]])
+    test_dependency = TestAddSurfaceRoughness
+    model = parameter(
+        [
+            "add_surface_roughness_full",
+            # "add_surface_roughness_half",
+            "add_surface_roughness_weighted",
+            "add_surface_roughness_boundaries",
+        ]
+    )
+
+
+@rfm.simple_test
+class TestAddSurfaceRoughnessMpiXY(MpiMixin, TestAddSurfaceRoughness):
+    tags = {"test", "mpi", "geometery", "fractal", "surface", "roughness"}
+    mpi_layout = parameter([[2, 2, 1], [3, 3, 1], [4, 4, 1]])
+    test_dependency = TestAddSurfaceRoughness
+    model = parameter(
+        [
+            "add_surface_roughness_small",
+            "add_surface_roughness_boundaries",
+        ]
+    )
 
 
 @rfm.simple_test