Fix creating groups with group() (#3431)

* Fix creating groups with group()

* Add bugfix entry

* Fix import order

* Rename 3431.bufix.rst to 3431.bugfix.rst

Author: dstansby

changes/3431.bugfix.rst

@@ -0,0 +1,2 @@
+Creating a new group with `zarr.group` no longer errors.
+This fixes a regression introduced in version 3.1.2.

src/zarr/api/asynchronous.py

@@ -670,38 +670,24 @@ async def group(
     g : group
         The new group.
     """
-
-    zarr_format = _handle_zarr_version_or_format(zarr_version=zarr_version, zarr_format=zarr_format)
-
     mode: AccessModeLiteral
     if overwrite:
         mode = "w"
     else:
-        mode = "r+"
-    store_path = await make_store_path(store, path=path, mode=mode, storage_options=storage_options)
-
-    if chunk_store is not None:
-        warnings.warn("chunk_store is not yet implemented", ZarrRuntimeWarning, stacklevel=2)
-    if cache_attrs is not None:
-        warnings.warn("cache_attrs is not yet implemented", ZarrRuntimeWarning, stacklevel=2)
-    if synchronizer is not None:
-        warnings.warn("synchronizer is not yet implemented", ZarrRuntimeWarning, stacklevel=2)
-    if meta_array is not None:
-        warnings.warn("meta_array is not yet implemented", ZarrRuntimeWarning, stacklevel=2)
-
-    if attributes is None:
-        attributes = {}
-
-    try:
-        return await AsyncGroup.open(store=store_path, zarr_format=zarr_format)
-    except (KeyError, FileNotFoundError):
-        _zarr_format = zarr_format or _default_zarr_format()
-        return await AsyncGroup.from_store(
-            store=store_path,
-            zarr_format=_zarr_format,
-            overwrite=overwrite,
-            attributes=attributes,
-        )
+        mode = "a"
+    return await open_group(
+        store=store,
+        mode=mode,
+        chunk_store=chunk_store,
+        cache_attrs=cache_attrs,
+        synchronizer=synchronizer,
+        path=path,
+        zarr_version=zarr_version,
+        zarr_format=zarr_format,
+        meta_array=meta_array,
+        attributes=attributes,
+        storage_options=storage_options,
+    )
 
 
 async def create_group(

tests/test_api/test_asynchronous.py

@@ -8,10 +8,12 @@
 import pytest
 
 from zarr import create_array
-from zarr.api.asynchronous import _get_shape_chunks, _like_args, open
+from zarr.api.asynchronous import _get_shape_chunks, _like_args, group, open
 from zarr.core.buffer.core import default_buffer_prototype
+from zarr.core.group import AsyncGroup
 
 if TYPE_CHECKING:
+    from pathlib import Path
     from typing import Any
 
     import numpy.typing as npt
@@ -103,3 +105,18 @@ async def test_open_no_array() -> None:
         TypeError, match=r"open_group\(\) got an unexpected keyword argument 'shape'"
     ):
         await open(store=store, shape=(1,))
+
+
+async def test_open_group_new_path(tmp_path: Path) -> None:
+    """
+    Test that zarr.api.asynchronous.group properly handles a string representation of a local file
+    path that does not yet exist.
+    See https://github.com/zarr-developers/zarr-python/issues/3406
+    """
+    # tmp_path exists, but tmp_path / "test.zarr" will not, which is important for this test
+    path = tmp_path / "test.zarr"
+    grp = await group(store=path, attributes={"a": 1})
+    assert isinstance(grp, AsyncGroup)
+    # Calling group on an existing store should just open that store
+    grp = await group(store=path)
+    assert grp.attrs == {"a": 1}