don't check if the abc is registered in test_all_classes_registered

numcodecs/tests/test_registry.py

@@ -34,6 +34,7 @@ def test_all_classes_registered():
         if (
             inspect.isclass(obj)
             and issubclass(obj, numcodecs.abc.Codec)
+            and hasattr(obj, 'codec_id')
             and obj.codec_id not in numcodecs.registry.codec_registry
             and obj.codec_id is not None  # remove `None`
         )