Fix/windows int32 issue (#3151)

* fix int32 inference on windows

* docstring

* pre-commit

* changelog

---------

Co-authored-by: Joe Hamman <[email protected]>

Author: d-v-b

changes/3151.bugfix.rst

@@ -0,0 +1,2 @@
+Fixed an issue preventing correct parsing of NumPy ``int32`` dtypes when constructed via
+``np.dtype('i')``.

src/zarr/core/dtype/npy/int.py

@@ -420,6 +420,26 @@ class Int32(BaseInt[np.dtypes.Int32DType, np.int32], HasEndianness):
     _zarr_v3_name: ClassVar[Literal["int32"]] = "int32"
     _zarr_v2_names: ClassVar[tuple[Literal[">i4"], Literal["<i4"]]] = (">i4", "<i4")
 
+    @classmethod
+    def _check_native_dtype(cls: type[Self], dtype: TBaseDType) -> TypeGuard[np.dtypes.Int32DType]:
+        """
+        A type guard that checks if the input is assignable to the type of ``cls.dtype_class``
+
+        This method is overridden for this particular data type because of a windows-specific issue where
+        np.dtype('i') is an instance of ``np.dtypes.IntDType``, not an instance of ``np.dtypes.Int32DType``.
+
+        Parameters
+        ----------
+        dtype : TDType
+            The dtype to check.
+
+        Returns
+        -------
+        Bool
+            True if the dtype matches, False otherwise.
+        """
+        return super()._check_native_dtype(dtype) or dtype == np.dtypes.Int32DType()
+
     @classmethod
     def from_native_dtype(cls: type[Self], dtype: TBaseDType) -> Self:
         if cls._check_native_dtype(dtype):

tests/test_dtype/test_npy/test_int.py

@@ -75,7 +75,10 @@ class TestInt16(BaseTestZDType):
 class TestInt32(BaseTestZDType):
     test_cls = Int32
     scalar_type = np.int32
-    valid_dtype = (np.dtype(">i4"), np.dtype("<i4"))
+    # The behavior of some tests associated with this class variable are
+    # order-dependent -- np.dtype('i') correctly fails certain tests only if it's not
+    # in the last position of the tuple. I have no idea how this is possible!
+    valid_dtype = (np.dtype("i"), np.dtype(">i4"), np.dtype("<i4"))
     invalid_dtype = (
         np.dtype(np.int8),
         np.dtype(np.uint16),