Change np.core.defchararray to np.char (#9165) (#9166)

* Change np.core.defchararray to np.char.chararray (#9165)

Replace a reference to np.core.defchararray with np.char.chararray
in xarray.testing.assertions, since the former no longer works on
NumPy 2.0.0 and the latter is the "preferred alias" according to
NumPy docs. See Issue #9165.

* Add test for assert_allclose on dtype S (#9165)

* Use np.char.decode, not np.char.chararray.decode

... in assertions._decode_string_data. See #9166.

* List #9165 fix in whats-new.rst

* cross-like the fixed function

* Improve a parameter ID in tests.test_assertions

Co-authored-by: Justus Magin <keewis@users.noreply.github.com>

* whats-new normalization

---------

Co-authored-by: Justus Magin <keewis@users.noreply.github.com>

doc/whats-new.rst

@@ -35,6 +35,8 @@ Deprecations
 
 Bug fixes
 ~~~~~~~~~
+- Make :py:func:`testing.assert_allclose` work with numpy 2.0 (:issue:`9165`, :pull:`9166`).
+  By `Pontus Lurcock <https://github.com/pont-us>`_.
 
 
 Documentation

xarray/testing/assertions.py

@@ -36,7 +36,7 @@ def wrapper(*args, **kwargs):
 
 def _decode_string_data(data):
     if data.dtype.kind == "S":
-        return np.core.defchararray.decode(data, "utf-8", "replace")
+        return np.char.decode(data, "utf-8", "replace")
     return data
 
 

xarray/tests/test_assertions.py

@@ -52,6 +52,11 @@ def test_allclose_regression() -> None:
             xr.Dataset({"a": ("x", [0, 2]), "b": ("y", [0, 1])}),
             id="Dataset",
         ),
+        pytest.param(
+            xr.DataArray(np.array("a", dtype="|S1")),
+            xr.DataArray(np.array("b", dtype="|S1")),
+            id="DataArray_with_character_dtype",
+        ),
     ),
 )
 def test_assert_allclose(obj1, obj2) -> None: