Add initial test

.gitignore

@@ -10,6 +10,7 @@ compile_commands.json
 CTestTestfile.cmake
 _deps
 build*
+/examples/__pycache__
 # pixi environments
 .pixi
 *.egg-info

examples/test_output.py

@@ -0,0 +1,37 @@
+from itertools import pairwise
+import os
+from pathlib import Path
+import numpy as np
+import pytest
+
+@pytest.mark.parametrize("filename", ["A", "Ciap", "pVp", "SENT"])
+def test_output(filename):
+    # Convert from the script location to where the output files should be located.
+    script_dir = Path(os.path.abspath(__file__)).parent
+    example_output_dir = script_dir.parent / "build" / "examples" / "geom_1"
+
+    with open(example_output_dir / f"{filename}_ref") as reference_output:
+        reference_output_lines = reference_output.readlines()
+
+    matrix_boundaries = [
+        line_num
+        for line_num, line in enumerate(reference_output_lines)
+        # Get header lines for matrices and blank last line.
+        if line.strip().endswith(":")
+    ] + [len(reference_output_lines)]
+
+    # Loop over each matrix in the file and compare to the reference.
+    for header_row, end_row in pairwise(matrix_boundaries):
+        start_row = header_row + 1
+        num_rows = end_row - start_row
+        matrix = np.loadtxt(
+            example_output_dir / filename,
+            skiprows=start_row,
+            max_rows=num_rows,
+        )
+        reference_matrix = np.loadtxt(
+            example_output_dir / f"{filename}_ref",
+            skiprows=start_row,
+            max_rows=num_rows,
+        )
+        assert matrix == pytest.approx(reference_matrix, rel=1e-6, abs=1e-6)