DEV: remove downstream test packages from environment.yml

[jorisvandenbossche]

xref #49998

[MarcoGorelli]

Cool, seems to be working!

Looks good to me pending green (well, barring #50124)

[jorisvandenbossche]

There is still a doc error from using statsmodels in an old whatsnew file, will convert that to plain code block.

[WillAyd]

lgtm when green

[MarcoGorelli]

There is still a doc error from using statsmodels in an old whatsnew file, will convert that to plain code block.

I went ahead and did this, hope it's OK

[jorisvandenbossche]

I went ahead and did this, hope it's OK

Sure!

[jorisvandenbossche]

Should we document in the contributing docs for now that you need to install a few additional packages to be able to run all tests in test_downstream.py ?
(pip/conda install seaborn scikit-learn statsmodels cftime pandas-datareader)

I am not fully sure this is necessarily worth mentioning (it makes the docs more complex with yet another note, while in practice contributors won't often need this)

[MarcoGorelli]

I think it's OK to not mention this - very few contributors will be running the downstream tests anyway, and for those who do, the error message will typically make it clear what they need to install

[jorisvandenbossche]

I additionally also removed pandas-gbq, because 1) this is actually a big dependency (with conda, indirectly it is still bringing in geopandas and its dependencies (GDAL etc)), and 2) we actually only need this for test_downstream.py so it is a "downstream" dependency in that sense (it seems that all actual tests of read_gbq / to_gbq have been removed because this functionality is tested in pandas-gbq itself now)

[phofl]

It would be nice to have a list of downstream dependencies somewhere. Not necessarily in the docs though. Maybe inside the test file itself?

[mroeschke]

LGTM (IMO fine either way documenting these need to be installed or not)