Fix some typing

xarray/backends/api.py

@@ -64,6 +64,7 @@
         NestedSequence,
         ReadBuffer,
         T_Chunks,
+        ZarrStoreLike,
     )
 
     T_NetcdfEngine = Literal["netcdf4", "scipy", "h5netcdf"]
@@ -2100,7 +2101,7 @@ def save_mfdataset(
 @overload
 def to_zarr(
     dataset: Dataset,
-    store: MutableMapping | str | os.PathLike[str] | None = None,
+    store: ZarrStoreLike | None = None,
     chunk_store: MutableMapping | str | os.PathLike | None = None,
     mode: ZarrWriteModes | None = None,
     synchronizer=None,
@@ -2123,7 +2124,7 @@ def to_zarr(
 @overload
 def to_zarr(
     dataset: Dataset,
-    store: MutableMapping | str | os.PathLike[str] | None = None,
+    store: ZarrStoreLike | None = None,
     chunk_store: MutableMapping | str | os.PathLike | None = None,
     mode: ZarrWriteModes | None = None,
     synchronizer=None,
@@ -2144,7 +2145,7 @@ def to_zarr(
 
 def to_zarr(
     dataset: Dataset,
-    store: MutableMapping | str | os.PathLike[str] | None = None,
+    store: ZarrStoreLike | None = None,
     chunk_store: MutableMapping | str | os.PathLike | None = None,
     mode: ZarrWriteModes | None = None,
     synchronizer=None,

xarray/backends/zarr.py

@@ -5,7 +5,7 @@
 import os
 import struct
 from collections.abc import Hashable, Iterable, Mapping
-from typing import TYPE_CHECKING, Any, Literal
+from typing import TYPE_CHECKING, Any, Literal, cast
 
 import numpy as np
 import pandas as pd
@@ -38,13 +38,10 @@
 from xarray.namedarray.utils import module_available
 
 if TYPE_CHECKING:
-    from zarr import Array as ZarrArray
-    from zarr import Group as ZarrGroup
-
     from xarray.backends.common import AbstractDataStore
     from xarray.core.dataset import Dataset
     from xarray.core.datatree import DataTree
-    from xarray.core.types import ReadBuffer
+    from xarray.core.types import ReadBuffer, ZarrArray, ZarrGroup
 
 
 def _get_mappers(*, storage_options, store, chunk_store):
@@ -108,8 +105,7 @@ def _choose_default_mode(
 
 
 def _zarr_v3() -> bool:
-    # TODO: switch to "3" once Zarr V3 is released
-    return module_available("zarr", minversion="2.99")
+    return module_available("zarr", minversion="3")
 
 
 # need some special secret attributes to tell us the dimensions
@@ -768,7 +764,7 @@ def __init__(
             self._members = self._fetch_members()
 
     @property
-    def members(self) -> dict[str, ZarrArray]:
+    def members(self) -> dict[str, ZarrArray | ZarrGroup]:
         """
         Model the arrays and groups contained in self.zarr_group as a dict. If `self._cache_members`
         is true, the dict is cached. Otherwise, it is retrieved from storage.
@@ -778,7 +774,7 @@ def members(self) -> dict[str, ZarrArray]:
         else:
             return self._members
 
-    def _fetch_members(self) -> dict[str, ZarrArray]:
+    def _fetch_members(self) -> dict[str, ZarrArray | ZarrGroup]:
         """
         Get the arrays and groups defined in the zarr group modelled by this Store
         """
@@ -1035,6 +1031,7 @@ def sync(self):
 
     def _open_existing_array(self, *, name) -> ZarrArray:
         import zarr
+        from zarr import Array as ZarrArray
 
         # TODO: if mode="a", consider overriding the existing variable
         # metadata. This would need some case work properly with region
@@ -1066,7 +1063,7 @@ def _open_existing_array(self, *, name) -> ZarrArray:
         else:
             zarr_array = self.zarr_group[name]
 
-        return zarr_array
+        return cast(ZarrArray, zarr_array)
 
     def _create_new_array(
         self, *, name, shape, dtype, fill_value, encoding, attrs

xarray/core/datatree_io.py

@@ -1,15 +1,18 @@
 from __future__ import annotations
 
-from collections.abc import Mapping, MutableMapping
+from collections.abc import Mapping
 from os import PathLike
-from typing import Any, Literal, get_args
+from typing import TYPE_CHECKING, Any, Literal, get_args
 
 from xarray.core.datatree import DataTree
 from xarray.core.types import NetcdfWriteModes, ZarrWriteModes
 
 T_DataTreeNetcdfEngine = Literal["netcdf4", "h5netcdf"]
 T_DataTreeNetcdfTypes = Literal["NETCDF4"]
 
+if TYPE_CHECKING:
+    from xarray.core.types import ZarrStoreLike
+
 
 def _datatree_to_netcdf(
     dt: DataTree,
@@ -78,7 +81,7 @@ def _datatree_to_netcdf(
 
 def _datatree_to_zarr(
     dt: DataTree,
-    store: MutableMapping | str | PathLike[str],
+    store: ZarrStoreLike,
     mode: ZarrWriteModes = "w-",
     encoding: Mapping[str, Any] | None = None,
     consolidated: bool = True,

xarray/core/types.py

@@ -70,8 +70,15 @@
 
     try:
         from zarr import Array as ZarrArray
+        from zarr import Group as ZarrGroup
     except ImportError:
-        ZarrArray = np.ndarray
+        ZarrArray = np.ndarray  # type: ignore[misc, assignment, unused-ignore]
+        ZarrGroup = Any  # type: ignore[misc, assignment, unused-ignore]
+    try:
+        # this is V3 only
+        from zarr.storage import StoreLike as ZarrStoreLike
+    except ImportError:
+        ZarrStoreLike = Any  # type: ignore[misc, assignment, unused-ignore]
 
     # Anything that can be coerced to a shape tuple
     _ShapeLike = Union[SupportsIndex, Sequence[SupportsIndex]]

xarray/tests/test_backends_datatree.py

@@ -414,7 +414,7 @@ def test_to_zarr_zip_store(self, tmpdir, simple_datatree):
         store = ZipStore(filepath)
         original_dt.to_zarr(store)
 
-        with open_datatree(store, engine="zarr") as roundtrip_dt:
+        with open_datatree(store, engine="zarr") as roundtrip_dt:  # type: ignore[arg-type, unused-ignore]
             assert_equal(original_dt, roundtrip_dt)
 
     def test_to_zarr_not_consolidated(self, tmpdir, simple_datatree):