Problems with `test_expects` with the lates version of xarray

[avalentino]

With Xarray v2025.12.0 I get the following unit test errors:

$ python3 -m pytest pint_xarray/tests/test_expects.py::TestExpects
=========================================================== test session starts ===========================================================
platform linux -- Python 3.13.11, pytest-9.0.2, pluggy-1.6.0
Matplotlib: 3.10.7+dfsg1
Freetype: 2.14.1
rootdir: /home/antonio/debian/git/pint-xarray
configfile: pyproject.toml
plugins: mock-3.15.1, recording-0.13.4, anyio-4.11.0, zarr-3.1.5, typeguard-4.4.4, hypothesis-6.150.0, mpl-0.17.0, timeout-2.4.0, cov-5.0.0, asyncio-1.3.0, xdist-3.8.0, requests_mock-1.12.1, mypy-plugins-3.2.0
asyncio: mode=Mode.STRICT, debug=False, asyncio_default_fixture_loop_scope=None, asyncio_default_test_loop_scope=function
collected 28 items                                                                                                                        

pint_xarray/tests/test_expects.py ..F.........F...............                                                                      [100%]

================================================================ FAILURES =================================================================
_____________________________________________ TestExpects.test_args[values2-units2-expected2] _____________________________________________

self = <pint_xarray.tests.test_expects.TestExpects object at 0x77d9f5b4cfc0>
values = (<xarray.DataArray ()> Size: 8B
<Quantity(4, 'kilometer')>, 2), units = ('m', None, None)
expected = <xarray.DataArray ()> Size: 8B
array(2000)

    @pytest.mark.parametrize(
        ["values", "units", "expected"],
        (
            ((ureg.Quantity(1, "m"), 2), ("mm", None, None), 500),
            ((ureg.Quantity(1, "m"), ureg.Quantity(0.5, "s")), ("mm", "ms", None), 2),
            (
                (xr.DataArray(4).pint.quantify("km"), 2),
                ("m", None, None),
                xr.DataArray(2000),
            ),
            (
                (
                    xr.DataArray([4, 2, 0]).pint.quantify("cm"),
                    xr.DataArray([4, 2, 1]).pint.quantify("mg"),
                ),
                ("m", "g", None),
                xr.DataArray([10, 10, 0]),
            ),
            (
                (ureg.Quantity(16, "m"), 2, ureg.Quantity(4, "s")),
                ("mm", None, "ms"),
                2,
            ),
        ),
    )
    def test_args(self, values, units, expected):
        @pint_xarray.expects(*units)
        def func(a, b, c=1):
            return a / (b * c)
    
        actual = func(*values)
    
        if isinstance(actual, xr.DataArray):
>           xr.testing.assert_identical(actual, expected)
E           AssertionError: Left and right DataArray objects are not identical
E           Attributes only on the left object:
E               units: meter

pint_xarray/tests/test_expects.py:47: AssertionError
____________________________________________ TestExpects.test_kwargs[values3-units3-expected3] ____________________________________________

self = <pint_xarray.tests.test_expects.TestExpects object at 0x77d9f5a592b0>
values = {'a': <xarray.DataArray ()> Size: 8B
<Quantity(4, 'kilometer')>, 'b': 2}, units = {'a': 'm', 'b': None, 'c': None}
expected = <xarray.DataArray ()> Size: 8B
array(4000)

    @pytest.mark.parametrize(
        ["values", "units", "expected"],
        (
            (
                {"a": ureg.Quantity(1, "m"), "b": 2},
                {"a": "mm", "b": None, "c": None},
                1000,
            ),
            (
                {"a": 2, "b": ureg.Quantity(100, "cm")},
                {"a": None, "b": "m", "c": None},
                4,
            ),
            (
                {"a": ureg.Quantity(1, "m"), "b": ureg.Quantity(0.5, "s")},
                {"a": "mm", "b": "ms", "c": None},
                4,
            ),
            (
                {"a": xr.DataArray(4).pint.quantify("km"), "b": 2},
                {"a": "m", "b": None, "c": None},
                xr.DataArray(4000),
            ),
            (
                {
                    "a": xr.DataArray([4, 2, 0]).pint.quantify("cm"),
                    "b": xr.DataArray([4, 2, 1]).pint.quantify("mg"),
                },
                {"a": "m", "b": "g", "c": None},
                xr.DataArray([20, 20, 0]),
            ),
        ),
    )
    def test_kwargs(self, values, units, expected):
        @pint_xarray.expects(**units)
        def func(a, b, c=2):
            return a / b * c
    
        actual = func(**values)
    
        if isinstance(actual, xr.DataArray):
>           xr.testing.assert_identical(actual, expected)
E           AssertionError: Left and right DataArray objects are not identical
E           Attributes only on the left object:
E               units: meter

pint_xarray/tests/test_expects.py:149: AssertionError
========================================================= short test summary info =========================================================
FAILED pint_xarray/tests/test_expects.py::TestExpects::test_args[values2-units2-expected2] - AssertionError: Left and right DataArray objects are not identical
FAILED pint_xarray/tests/test_expects.py::TestExpects::test_kwargs[values3-units3-expected3] - AssertionError: Left and right DataArray objects are not identical
====================================================== 2 failed, 26 passed in 4.69s =======================================================