From 7bcf2ca9e8919f5ba51e06d06a9e5e9f3c30ec04 Mon Sep 17 00:00:00 2001
From: agnelson <agnelson@anl.gov>
Date: Tue, 27 Jul 2021 19:03:38 -0500
Subject: [PATCH] Adding a check to ensure we dont translate a cell not filled
 with a universe and then incorporating this in the unit test.

---
 src/cell.cpp                 |  6 ++++++
 tests/unit_tests/test_lib.py | 40 ++++++++++++++++++++++++++++++------
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/src/cell.cpp b/src/cell.cpp
index 6011081d76..a586677730 100644
--- a/src/cell.cpp
+++ b/src/cell.cpp
@@ -1318,6 +1318,12 @@ extern "C" int openmc_cell_get_translation(int32_t index, double xyz[])
 extern "C" int openmc_cell_set_translation(int32_t index, const double xyz[])
 {
   if (index >= 0 && index < model::cells.size()) {
+    if (model::cells[index]->fill_ == C_NONE) {
+      set_errmsg(fmt::format("Cannot apply a translation to cell {}"
+                             " because it is not filled with another universe",
+                             index));
+      return OPENMC_E_GEOMETRY;
+    }
     model::cells[index]->translation_ = Position(xyz);
     return 0;
   } else {
diff --git a/tests/unit_tests/test_lib.py b/tests/unit_tests/test_lib.py
index 8ec12efdd3..0375f1437c 100644
--- a/tests/unit_tests/test_lib.py
+++ b/tests/unit_tests/test_lib.py
@@ -99,6 +99,21 @@ def lib_run(lib_simulation_init):
     openmc.lib.run()
 
 
+@pytest.fixture(scope='module')
+def pincell_model_w_univ():
+    """Set up a model to test with and delete files when done"""
+    openmc.reset_auto_ids()
+    pincell = openmc.examples.pwr_pin_cell()
+    clad_univ = openmc.Universe(cells=[openmc.Cell(fill=pincell.materials[1])])
+    pincell.geometry.root_universe.cells[2].fill = clad_univ
+    pincell.settings.verbosity = 1
+
+    # Write XML files in tmpdir
+    with cdtemp():
+        pincell.export_to_xml()
+        yield
+
+
 def test_cell_mapping(lib_init):
     cells = openmc.lib.cells
     assert isinstance(cells, Mapping)
@@ -141,12 +156,6 @@ def test_properties_temperature(lib_init):
     openmc.lib.import_properties('properties.h5')
     assert cell.get_temperature() == pytest.approx(200.0)
 
-def test_cell_translation(lib_init):
-    cell = openmc.lib.cells[1]
-    assert cell.get_translation() == pytest.approx([0., 0., 0.])
-    cell.set_translation(np.array([1., 0., -1.]))
-    assert cell.get_translation() == pytest.approx([1., 0., -1.])
-
 
 def test_new_cell(lib_init):
     with pytest.raises(exc.AllocationError):
@@ -699,3 +708,22 @@ def test_trigger_set_n_batches(uo2_trigger_model, mpi_intracomm):
     # Ensure statepoint was created only at batch 20 when calling set_batches
     assert not os.path.exists('statepoint.12.h5')
     assert os.path.exists('statepoint.20.h5')
+
+
+def test_cell_translation(pincell_model_w_univ, mpi_intracomm):
+    openmc.lib.finalize()
+    openmc.lib.init(intracomm=mpi_intracomm)
+    openmc.lib.simulation_init()
+    # Cell 1 is filled with a material so it has a translation, but we can't
+    # set it.
+    cell = openmc.lib.cells[1]
+    assert cell.get_translation() == pytest.approx([0., 0., 0.])
+    with pytest.raises(exc.GeometryError, match='not filled with'):
+        cell.set_translation(np.array([1., 0., -1.]))
+
+    # Cell 2 was given a universe, so we can assign it a translation vector
+    cell = openmc.lib.cells[2]
+    assert cell.get_translation() == pytest.approx([0., 0., 0.])
+    # This time we *can* set it
+    cell.set_translation(np.array([1., 0., -1.]))
+    assert cell.get_translation() == pytest.approx([1., 0., -1.])