CI: xarray upgrade to 0.19 broke CI Checks pipeline

[phofl]

Xarray was recently upgrade from 0.18.2 to 0.19 in our ci. This broke the checks pipeline

Passing:
https://github.com/pandas-dev/pandas/runs/3155104841

Failing:
https://github.com/pandas-dev/pandas/pull/42713/checks?check_run_id=3155841275

[phofl]

Following errors happen:

 Performing static analysis using mypy
/usr/share/miniconda/envs/pandas-dev/lib/python3.8/site-packages/xarray/core/common.py:1659: error: INTERNAL ERROR -- Please try using mypy master on Github:
https://mypy.readthedocs.io/en/stable/common_issues.html#using-a-development-mypy-build
If this issue continues with mypy master, please report a bug at https://github.com/python/mypy/issues
version: 0.910
/usr/share/miniconda/envs/pandas-dev/lib/python3.8/site-packages/xarray/core/common.py:1659: : note: please use --show-traceback to print a traceback when reporting a bug
Performing static analysis using mypy DONE
Error: Process completed with exit code 2.

Some mypy issue

Doctest issue:

 _______________ [doctest] pandas.core.generic.NDFrame.to_xarray ________________
3086 
3087         >>> df_multiindex
3088                            speed
3089         date       animal
3090         2018-01-01 falcon    350
3091                    parrot     18
3092         2018-01-02 falcon    361
3093                    parrot     15
3094 
3095         >>> df_multiindex.to_xarray()
Differences (unified diff with -expected +actual):
    @@ -1,4 +1,4 @@
     <xarray.Dataset>
    -Dimensions:  (animal: 2, date: 2)
    +Dimensions:  (date: 2, animal: 2)
     Coordinates:
       * date     (date) datetime64[ns] 2018-01-01 2018-01-02

[simonjayhawkins]

changing milestone to 1.3.5

[jbrockmendel]

both of these persist with xarray 0.20.1

[simonjayhawkins]

xarray is a py.typed library and this was also the case for xarray 0.18.2 (since v0.12.4 pydata/xarray#3112)

Not sure what the mypy error is all about but adding an empty xarray.pyi file in our typings directory allows mypy to run and is green (for xarray 0.20.1), so could do this if unpinning xarray is considered more important than type checking against xarray.

[simonjayhawkins]

removing from 1.3.x milestone as I don't think there is anything that needs to done for 1.3.x and this is just a ci issue? So having xarray pinned on 1.3.x is nbd.

[jbrockmendel]

There are several ci/deps/ files where xarray version is not pinned. Does that indicate this issue is resolved?

[phofl]

I think it only caused the typing checks to fail, nothing else

[jbrockmendel]

OK. Do we have a way of checking when this is resolved?

[MarcoGorelli]

closing as it looks like CI is fine now

[simonjayhawkins]

xarray is still pinned in environment.yaml, xarray<0.19. local environment resolving to 0.18.2

mypy is now passing locally with both xarray 0.19.0 and xarray 0.20.1, so I guess that the issue has been resolved by some changes in pandas itself.

I think we should not close this issue until xarray is unpinned.

[djgray780]

take

[djgray780]

This is my first contribution to pandas and open-source in general, but I am pretty sure that my PR 47016 is ready for review/merge.

[simonjayhawkins]

mypy is now passing locally with both xarray 0.19.0 and xarray 0.20.1, so I guess that the issue has been resolved by some changes in pandas itself.

xref #47016 (review), doctest issue mentioned in #42716 (comment) still persists.

[mroeschke]

Closed by #47016