add test_occupants.py

python/tests/test_occupants.py

@@ -0,0 +1,41 @@
+import os
+import numpy as np
+from libcasm.xtal import Occupant
+
+
+def test_occupant_from_xyz(session_shared_datadir):
+    """Test making xtal.Occupant.from_xyz_string()
+    method
+
+    Parameters
+    ----------
+    shared_datadir : str
+
+    Returns
+    -------
+    None
+
+    """
+
+    with open(
+        os.path.join(session_shared_datadir, "input_molecules", "water.xyz"), "r"
+    ) as f:
+        water_xyz_string = f.read()
+
+    water = Occupant.from_xyz_string(water_xyz_string)
+
+    assert water.name() == "Water"
+
+    expected_atom_names = ["O", "H", "H"]
+    expected_atom_coords = [
+        np.array([0.0, 0.0, 0.11779]),
+        np.array([0.0, 0.75545, -0.47116]),
+        np.array([0.0, -0.75545, -0.47116]),
+    ]
+
+    for atom, expected_atom_name, expected_atom_coord in zip(
+        water.atoms(), expected_atom_names, expected_atom_coords
+    ):
+
+        assert atom.name() == expected_atom_name
+        assert np.allclose(atom.coordinate(), expected_atom_coord)