Add test for source file generation

tests/unit_tests/test_source_file.py

@@ -0,0 +1,38 @@
+from random import random
+
+import h5py
+import numpy as np
+import openmc
+
+
+def test_source_file(run_in_tmpdir):
+    # Create source particles
+    source = []
+    n = 1000
+    for i in range(n):
+        source.append(openmc.SourceParticle(
+            r=(random(), i, 0),
+            u=(0., 0., 1.),
+            E=float(n - i),
+        ))
+
+    # Create source file
+    openmc.write_source_file(source, 'test_source.h5')
+
+    # Get array of source particles from file
+    with h5py.File('test_source.h5', 'r') as fh:
+        arr = fh['source_bank'][...]
+
+    # Ensure data is consistent
+    r = arr['r']
+    assert np.all((r['x'] > 0.0) & (r['x'] < 1.0))
+    assert np.all(r['y'] == np.arange(1000))
+    assert np.all(r['z'] == 0.0)
+    u = arr['u']
+    assert np.all(u['x'] == 0.0)
+    assert np.all(u['y'] == 0.0)
+    assert np.all(u['z'] == 1.0)
+    assert np.all(arr['E'] == n - np.arange(n))
+    assert np.all(arr['wgt'] == 1.0)
+    assert np.all(arr['delayed_group'] == 0)
+    assert np.all(arr['particle'] == 0)