Add tests for HarmonicWigner class

tests/conftest.py

@@ -0,0 +1,60 @@
+import ase
+import pytest
+
+
+@pytest.fixture
+def mock_h2o_molecule():
+    """Create a simple water molecule for testing"""
+    positions = [
+        [0.0, 0.0, 0.0],  # O
+        [0.0, 0.757, 0.586],  # H
+        [0.0, -0.757, 0.586],
+    ]  # H
+    return ase.Atoms("OH2", positions=positions)
+
+
+@pytest.fixture
+def mock_h2o_frequencies():
+    """Mock H2O vibrational frequencies in cm^-1"""
+    # Real vibrational frequencies for H2O
+    return [
+        3657.0,  # symmetric stretch
+        3756.0,  # antisymmetric stretch
+        1595.0,
+    ]  # bending
+
+
+@pytest.fixture
+def mock_h2o_vibrations():
+    """Mock vibrational normal modes"""
+    # Simplified normal modes for testing
+    vibrations = []
+
+    # Symmetric stretch - both H atoms move in same direction
+    vibrations.append(
+        [
+            [0.0, 0.0, 0.0],  # O stays relatively still
+            [0.0, 0.0, 1.0],  # H1 moves up
+            [0.0, 0.0, 1.0],  # H2 moves up
+        ]
+    )
+
+    # Antisymmetric stretch - H atoms move in opposite directions
+    vibrations.append(
+        [
+            [0.0, 0.0, 0.0],  # O stays relatively still
+            [0.0, 0.0, 1.0],  # H1 moves up
+            [0.0, 0.0, -1.0],  # H2 moves down
+        ]
+    )
+
+    # Bending - H atoms move in opposite directions perpendicular to bonds
+    vibrations.append(
+        [
+            [0.0, 0.0, 0.0],  # O stays relatively still
+            [0.0, 1.0, 0.0],  # H1 moves right
+            [0.0, -1.0, 0.0],  # H2 moves left
+        ]
+    )
+
+    return vibrations