Add test for cell complement

Author: paulromano

tests/test_geometry.py

@@ -0,0 +1,29 @@
+from textwrap import dedent
+
+from pytest import mark
+from openmc_mcnp_adapter import mcnp_str_to_model
+
+
+@mark.parametrize("whitespace", ["", " ", "\t"])
+def test_cell_complement(whitespace):
+    # Cell 2 corresponds to r < 2 intersected with z > 0
+    mcnp_str = dedent(f"""
+    title
+    100  1.0  +1 : -2
+    2    1.0  #{whitespace}100
+
+    1  so 2.0
+    2  pz 0.0
+
+    m1   1001.80c  1.0
+    """)
+    model = mcnp_str_to_model(mcnp_str)
+    cell = model.geometry.get_all_cells()[2]
+
+    # Check various points
+    assert (0., 0., 0.1) in cell.region
+    assert (0., 0., -0.1) not in cell.region
+    assert (0., 0., 1.99) in cell.region
+    assert (0., 0., 2.01) not in cell.region
+    assert (1., 1., 1.) in cell.region
+    assert (2., 0., 1.) not in cell.region