added two tests to check centre was written/read to/from xml

tests/unit_tests/test_cylindrical_mesh.py

@@ -0,0 +1,30 @@
+import openmc
+import numpy as np
+
+def test_centre_read_write_to_xml():
+    """Tests that the centre attribute can be written and read back to XML
+    """
+    # build
+    mesh = openmc.CylindricalMesh()
+    mesh.phi_grid = [1, 2, 3]
+    mesh.z_grid = [1, 2, 3]
+    mesh.r_grid = [1, 2, 3]
+
+    mesh.centre = [0.1, 0.2, 0.3]
+
+    tally = openmc.Tally()
+
+    mesh_filter = openmc.MeshFilter(mesh)
+    tally.filters.append(mesh_filter)
+
+    tally.scores.append("heating")
+
+    tallies = openmc.Tallies([tally])
+
+    tallies.export_to_xml()
+
+    # read back
+    new_tallies = openmc.Tallies.from_xml()
+    new_tally = new_tallies[0]
+    new_mesh = new_tally.filters[0].mesh
+    assert np.allclose(new_mesh.centre, mesh.centre)

tests/unit_tests/test_spherical_mesh.py

@@ -0,0 +1,30 @@
+import openmc
+import numpy as np
+
+def test_centre_read_write_to_xml():
+    """Tests that the centre attribute can be written and read back to XML
+    """
+    # build
+    mesh = openmc.SphericalMesh()
+    mesh.phi_grid = [1, 2, 3]
+    mesh.theta_grid = [1, 2, 3]
+    mesh.r_grid = [1, 2, 3]
+
+    mesh.centre = [0.1, 0.2, 0.3]
+
+    tally = openmc.Tally()
+
+    mesh_filter = openmc.MeshFilter(mesh)
+    tally.filters.append(mesh_filter)
+
+    tally.scores.append("heating")
+
+    tallies = openmc.Tallies([tally])
+
+    tallies.export_to_xml()
+
+    # read back
+    new_tallies = openmc.Tallies.from_xml()
+    new_tally = new_tallies[0]
+    new_mesh = new_tally.filters[0].mesh
+    assert np.allclose(new_mesh.centre, mesh.centre)