issue_comments: 774001075

@keewis The following test is giving me trouble: pytest xarray/tests/test_units.py::test_align_dataarray[int64-10-data-compatible_unit]

https://github.com/pydata/xarray/blob/5735e163bea43ec9bc3c2e640fbf25a1d4a9d0c0/xarray/tests/test_units.py#L461

I now try to reproduce what it does but I cannot even manage that... I think the following is what the test does but it fails with DimensionalityError: Cannot convert from 'dimensionless' to 'meter' - can you see what I do wrong/ different from the test?

```python import numpy as np import pint import xarray as xr

unit_registry = pint.UnitRegistry()

dtype = np.int64

data_unit1 = unit_registry.m data_unit2 = unit_registry.mm

array1 = np.linspace(0, 10, 2 * 5).reshape(2, 5).astype(dtype) array2 = np.linspace(0, 8, 2 * 5).reshape(2, 5).astype(dtype)

x = np.arange(2) # * dim_unit1 y1 = np.arange(5) # * dim_unit1 y2 = np.arange(2, 7) # * dim_unit2

u1 = np.array([3, 5, 7, 8, 9]) # * coord_unit1 u2 = np.array([7, 8, 9, 11, 13]) # * coord_unit2

coords1 = {"x": x, "y": y1} coords2 = {"x": x, "y": y2}

data_array1 = xr.DataArray(data=array1 * data_unit1, coords=coords1, dims=("x", "y")) data_array2 = xr.DataArray(data=array2 * data_unit2, coords=coords2, dims=("x", "y"))

fill_value = 10

actual_a, actual_b = xr.align(data_array1, data_array2, join="outer", fill_value=fill_value * data_unit1)

```

---

The underlying problem is that when I run this test with check_dtype=True it raises an error (which is fine) but instead of a nice diff_repr it elevates the UnitStrippedWarning to an error and I have not the slightest clue why...

```python-traceback > assert_allclose(expected_b, actual_b) /home/mathause/code/xarray/xarray/tests/test_units.py:542: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ /home/mathause/code/xarray/xarray/tests/__init__.py:208: in assert_allclose xarray.testing.assert_allclose(a, b, check_dtype=check_dtype, **kwargs) /home/mathause/code/xarray/xarray/testing.py:178: in assert_allclose assert allclose, formatting.diff_array_repr( /home/mathause/code/xarray/xarray/core/formatting.py:667: in diff_array_repr if not equiv(a, b, check_dtype=check_dtype): /home/mathause/code/xarray/xarray/testing.py:40: in _data_allclose_or_equiv return duck_array_ops.allclose_or_equiv( /home/mathause/code/xarray/xarray/core/duck_array_ops.py:249: in allclose_or_equiv arr1 = asarray(arr1) /home/mathause/code/xarray/xarray/core/duck_array_ops.py:184: in asarray return data if is_duck_array(data) else xp.asarray(data) /home/mathause/conda/envs/xarray_dev/lib/python3.8/site-packages/numpy/core/_asarray.py:102: in asarray return array(a, dtype, copy=False, order=order) /home/mathause/code/xarray/xarray/core/common.py:139: in __array__ return np.asarray(self.values, dtype=dtype) /home/mathause/code/xarray/xarray/core/dataarray.py:634: in values return self.variable.values /home/mathause/code/xarray/xarray/core/variable.py:544: in values return _as_array_or_item(self._data) /home/mathause/code/xarray/xarray/core/variable.py:276: in _as_array_or_item data = np.asarray(data) /home/mathause/conda/envs/xarray_dev/lib/python3.8/site-packages/numpy/core/_asarray.py:102: in asarray return array(a, dtype, copy=False, order=order) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ self = <Quantity([[10. 10. 0. 0. 1. 2. 3.] [10. 10. 4. 5. 6. 7. 8.]], 'millimeter')>, t = None def __array__(self, t=None): > warnings.warn( "The unit of the quantity is stripped when downcasting to ndarray.", UnitStrippedWarning, stacklevel=2, ) E pint.errors.UnitStrippedWarning: The unit of the quantity is stripped when downcasting to ndarray. /home/mathause/conda/envs/xarray_dev/lib/python3.8/site-packages/pint/quantity.py:1683: UnitStrippedWarning ```