raise error when we can be sure there is no object codec

Author: alimanfoo

zarr/tests/test_core.py

@@ -876,9 +876,14 @@ def test_dtypes(self):
     def test_object_arrays(self):
 
         # an object_codec is required for object arrays
-        with pytest.warns(FutureWarning):
+        with pytest.raises(ValueError):
             self.create_array(shape=10, chunks=3, dtype=object)
 
+        # an object_codec is required for object arrays, but allow to be provided via
+        # filters to maintain API backwards compatibility
+        with pytest.warns(FutureWarning):
+            self.create_array(shape=10, chunks=3, dtype=object, filters=[MsgPack()])
+
         # create an object array using msgpack
         z = self.create_array(shape=10, chunks=3, dtype=object, object_codec=MsgPack())
         z[0] = 'foo'