Add more fixtures used in pandas extension testing

[mroeschke]

xref pandas-dev/pandas#56583 (comment)

[martinfleis]

Thanks! I am fine with this right now but I'm wondering if it is a right solution. Assuming there's a number of downstream packages implementing EAs, this would need to be done in every one of them. Wouldn't it be better to ensure that EA tests just work without a need to define generic fixtures for every EA implementation? I would assume that you only override those that are affected by the specifics of your EA and inherit the rest but that is not the case at the moment.

[jorisvandenbossche]

Yes, we have always ensured on the pandas side that the base extension array tests don't use other fixtures than the ones defined in those tests itself. I think we should continue on that path (otherwise it is very hard to know as downstream user which fixtures should be implemented).

I think we can simply revert the small part of pandas-dev/pandas#56583 that touches the extension tests. Ideally we would have a better test on the pandas side to remind us of this contract, so we don't easily break that with such "cleaning" PRs.

[mroeschke]

Yeah agreed a better long term solution is needed on the pandas side to avoid this. Opened up pandas-dev/pandas#56735 to track this

[jorisvandenbossche]

I did a PR to pandas to fix it there, and we have the issue to add better testing for this. That resolves this for now on the geopandas side, so closing this PR.