This seems to fail a lot; can we get it in 3.2.1 too?

Is there an existing "make this a safe name" function someplace in the standard library or do we have to roll our own here?

Is there an existing "make this a safe name" function someplace in the standard library or do we have to roll our own here?

I'm not aware of anything like that. If anything I'd expect that in pathlib, but it is OS-depended, so would need to be handled in PurePosixPath \ PureWindowsPath.

The failure was

_________________________ test_loglog_nonpos[png-True] _________________________
[gw0] linux -- Python 3.8.2 /opt/hostedtoolcache/Python/3.8.2/x64/bin/python

expected = '/home/vsts/work/1/s/result_images/test_axes/test_loglog_nonpos-expected.png'
actual = '/home/vsts/work/1/s/result_images/test_axes/test_loglog_nonpos.png'
tol = 0, in_decorator = True

This makes me think that we should be doing something similar in compare_images...

abc9445 adds the comment from @QuLogic

            # This is hacked on via the mpl_image_comparison_parameters fixture
            # so that we don't need to modify the function's real signature for
            # any parametrization. Modifying the signature is very very tricky
            # and likely to confuse pytest.

which is definitely true! I think the tools we can use to do this are better now (3 years later).

Might be worth re-visiting that decorator to see if we can make in simpler (and stop using the in-direct fixtur paramterization that pytest tried to deprecate).

Indeed the check_figures_equal decorator does things in a much simpler way, without indirection. On the other hand, the backport of #16770 in #16791 seems to have failed in some way due to that decorator.

With #15199 backported, I think we should be able to backport this as well without conflicts.

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

$ git checkout v3.2.x
$ git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

$ git cherry-pick -m1 b4a414fd5abf1b3b930bf3319ed9d1802db47be6

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

$ git commit -am 'Backport PR #16693: TST: use pytest name in naming files for check_figures_equal'

4. Push to a named branch :

git push YOURFORK v3.2.x:auto-backport-of-pr-16693-on-v3.2.x

5. Create a PR against branch v3.2.x, I would have named this PR:

"Backport PR #16693 on branch v3.2.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to suggest an improvement.

So we needed #15589 to avoid conflicts; it seems pretty non-controversial, so I included it in the backport above.

This seems to have crossed with #16707, which has a test that takes request:

______ ERROR collecting lib/matplotlib/tests/test_marker.py _____
lib/matplotlib/tests/test_marker.py:105: in <module>
    @check_figures_equal(tol=1.45)
lib/matplotlib/testing/decorators.py:419: in decorator
    inspect.Parameter("request", KEYWORD_ONLY),
/var/container/conda/envs/mpl37/lib/python3.7/inspect.py:2856: in replace
    return_annotation=return_annotation)
/var/container/conda/envs/mpl37/lib/python3.7/inspect.py:2795: in __init__
    raise ValueError(msg)
E   ValueError: duplicate parameter name: 'request'

so I guess there's a reason I wrote that indirection comment...