Fix: respect write_empty_chunks when opening an existing array (#3378)

* Fix: respect write_empty_chunks when opening an existing array

* doc: add release notes

Author: ianhi

changes/3378.bugfix.rst

@@ -0,0 +1,3 @@
+Ensure passing `config` is handled properly when `open`ing an existing
+array.
+

src/zarr/api/asynchronous.py

@@ -358,7 +358,9 @@ async def open(
             zarr_format = _metadata_dict["zarr_format"]
             is_v3_array = zarr_format == 3 and _metadata_dict.get("node_type") == "array"
             if is_v3_array or zarr_format == 2:
-                return AsyncArray(store_path=store_path, metadata=_metadata_dict)
+                return AsyncArray(
+                    store_path=store_path, metadata=_metadata_dict, config=kwargs.get("config")
+                )
         except (AssertionError, FileNotFoundError, NodeTypeValidationError):
             pass
         return await open_group(store=store_path, zarr_format=zarr_format, mode=mode, **kwargs)

tests/test_api.py

@@ -123,6 +123,30 @@ def test_write_empty_chunks_warns(write_empty_chunks: bool, zarr_format: ZarrFor
         )
 
 
+@pytest.mark.parametrize("zarr_format", [2, 3])
+def test_open_array_respects_write_empty_chunks_config(zarr_format: ZarrFormat) -> None:
+    """Test that zarr.open() respects write_empty_chunks config."""
+    store = MemoryStore()
+
+    _ = zarr.create(
+        store=store,
+        path="test_array",
+        shape=(10,),
+        chunks=(5,),
+        dtype="f8",
+        fill_value=0.0,
+        zarr_format=zarr_format,
+    )
+
+    arr2 = zarr.open(store=store, path="test_array", config={"write_empty_chunks": True})
+    assert isinstance(arr2, zarr.Array)
+
+    assert arr2._async_array._config.write_empty_chunks is True
+
+    arr2[0:5] = np.zeros(5)
+    assert arr2.nchunks_initialized == 1
+
+
 @pytest.mark.parametrize("path", ["foo", "/", "/foo", "///foo/bar"])
 @pytest.mark.parametrize("node_type", ["array", "group"])
 def test_open_normalized_path(