issue_comments: 895935131

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https://github.com/pydata/xarray/pull/5684#issuecomment-895935131 https://api.github.com/repos/pydata/xarray/issues/5684 895935131 IC_kwDOAMm_X841ZuKb 14371165 2021-08-10T11:02:10Z 2021-08-10T11:15:17Z MEMBER

I noticed this issue because my local mypy version was complaining about: xrtools.py:750: error: Signature of "open_dataset" incompatible with supertype "BackendEntrypoint"

Anyone have any ideas why the CI version doesn't complain about this?

The original test function did not have any typing defined. For mypy to do any signature checking either of the inputs or outputs needs to be typed.

This will throw the supertype error, uncomment self to get it passing: ```python import numpy as np import xarray as xr from xarray.backends import BackendEntrypoint

expected = xr.Dataset( dict(a=2 * np.arange(5)), coords=dict(x=("x", np.arange(5), dict(units="s"))) )

class CustomBackend(BackendEntrypoint): def open_dataset( # self, filename_or_obj, drop_variables=None, **kwargs, ) -> xr.Dataset: return expected.copy(deep=True) ```

 
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