implement .chunks on v3 arrays (zarr-developers#1929)

* implement .chunks on v3 arrays

* remove noqa: B009

* make mypy happy

* only return chunks for regular chunk grids

---------

Co-authored-by: Davis Bennett <davis.v.bennett@gmail.com>
Co-authored-by: Joseph Hamman <joe@earthmover.io>

Author: 3 people

src/zarr/array.py

@@ -366,6 +366,15 @@ def ndim(self) -> int:
     def shape(self) -> ChunkCoords:
         return self.metadata.shape
 
+    @property
+    def chunks(self) -> ChunkCoords:
+        if isinstance(self.metadata.chunk_grid, RegularChunkGrid):
+            return self.metadata.chunk_grid.chunk_shape
+        else:
+            raise ValueError(
+                f"chunk attribute is only available for RegularChunkGrid, this array has a {self.metadata.chunk_grid}"
+            )
+
     @property
     def size(self) -> int:
         return np.prod(self.metadata.shape).item()
@@ -639,6 +648,10 @@ def ndim(self) -> int:
     def shape(self) -> ChunkCoords:
         return self._async_array.shape
 
+    @property
+    def chunks(self) -> ChunkCoords:
+        return self._async_array.chunks
+
     @property
     def size(self) -> int:
         return self._async_array.size

tests/v3/test_group.py

@@ -79,7 +79,7 @@ def test_group(store: MemoryStore | LocalStore) -> None:
     assert arr.dtype == data.dtype
 
     # TODO: update this once the array api settles down
-    # assert arr.chunk_shape == (2, 2)
+    assert arr.chunks == (2, 2)
 
     bar2 = foo["bar"]
     assert dict(bar2.attrs) == {"baz": "qux"}