Fix default fill_value

src/zarr/core/array.py

@@ -250,12 +250,6 @@ async def _create_v3(
         shape = parse_shapelike(shape)
         codecs = list(codecs) if codecs is not None else [BytesCodec()]
 
-        if fill_value is None:
-            if dtype == np.dtype("bool"):
-                fill_value = False
-            else:
-                fill_value = 0
-
         if chunk_key_encoding is None:
             chunk_key_encoding = ("default", "/")
         assert chunk_key_encoding is not None
@@ -279,7 +273,6 @@ async def _create_v3(
         )
 
         array = cls(metadata=metadata, store_path=store_path)
-
         await array._save_metadata(metadata)
         return array
 

src/zarr/core/buffer/core.py

@@ -464,6 +464,9 @@ def __repr__(self) -> str:
 
     def all_equal(self, other: Any, equal_nan: bool = True) -> bool:
         """Compare to `other` using np.array_equal."""
+        if other is None:
+            # Handle None fill_value for Zarr V2
+            return False
         # use array_equal to obtain equal_nan=True functionality
         data, other = np.broadcast_arrays(self._data, other)
         result = np.array_equal(self._data, other, equal_nan=equal_nan)

src/zarr/core/metadata/v3.py

@@ -322,7 +322,7 @@ def parse_fill_value(
     A scalar instance of `dtype`
     """
     if fill_value is None:
-        return dtype.type(0)  # type: ignore[call-overload]
+        fill_value = 0
     if isinstance(fill_value, Sequence) and not isinstance(fill_value, str):
         if dtype.type in (np.complex64, np.complex128):
             dtype = cast(COMPLEX_DTYPE, dtype)

src/zarr/testing/strategies.py

@@ -74,7 +74,8 @@ def arrays(
     path = draw(paths)
     name = draw(array_names)
     attributes = draw(attrs)
-    fill_value = draw(npst.from_dtype(nparray.dtype))
+    # test that None works too.
+    fill_value = draw(st.one_of([st.none(), npst.from_dtype(nparray.dtype)]))
     # compressor = draw(compressors)
 
     expected_attrs = {} if attributes is None else attributes
@@ -88,11 +89,12 @@ def arrays(
         chunks=chunks,
         dtype=nparray.dtype,
         attributes=attributes,
-        # compressor=compressor,  # TODO: FIXME
+        # compressor=compressor,  # FIXME
         fill_value=fill_value,
     )
 
     assert isinstance(a, Array)
+    assert a.fill_value is not None
     assert isinstance(root[array_path], Array)
     assert nparray.shape == a.shape
     assert chunks == a.chunks