Add test to validate python module reading of unfinished parts

src/wrappers/python/tests/test_unittest.py

@@ -637,6 +637,34 @@ def test_write_float(self):
 
         os.remove(outfilename)
 
+    def test_unfinished_multipart_load(self):
+
+        #
+        # Multipart files may list more part headers than have valid
+        # pixel data (interrupted write). Loading should return only
+        # parts whose pixels read successfully, not fail the entire
+        # file open.
+        #
+        # The test file unfinished_multipart.exr has 4 parts, 2 valid
+        # and 2 invalid. The default read should return 2 parts; the
+        # header_only read should return all 4 parts.
+        #
+
+        path = f"{test_dir}/unfinished_multipart.exr"
+        num_parts = 4
+        num_good = 2
+
+        with OpenEXR.File(path, separate_channels=True) as f:
+            self.assertEqual(len(f.parts), num_good)
+            for i in range(num_good):
+                self.assertIn('Z', f.parts[i].channels)
+                self.assertEqual(f.parts[i].channels['Z'].pixels.shape, (8, 8))
+            self.assertEqual(f.parts[0].name(), 'Part0')
+            self.assertEqual(f.parts[1].name(), 'Part1')
+
+        with OpenEXR.File(path, separate_channels=True, header_only=True) as f:
+            self.assertEqual(len(f.parts), num_parts)
+
     def test_write_2part(self):
 
         #