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Returning fig is incompatible with pytest 7.2 (when test uses marker but pytest-mpl not installed) #183
Description
As @WilliamJamieson discovered in astropy/astropy#13892 , we now see PytestReturnNotNoneWarning with pytest 7.2 that will eventually become an exception in future releases. If there is no way to opt out (asking at pytest-dev/pytest#10427), can this plugin still work without return fig?
Activity
nicoddemus commentedon Oct 25, 2022
Hey, pytest maintainer here.
Here is the related code in pytest:
https://github.com/pytest-dev/pytest/blob/f07017f91b6af5a7c6942868cb61aea72be4ac31/src/_pytest/python.py#L188-L205
I see pytest-mpl uses a hookwrapper over
pytest_runtest_call, what might be needed is to make a hookwrapper overpytest_pyfunc_callwhich also sets the return value toNone.https://pluggy.readthedocs.io/en/stable/#wrappers
WilliamJamieson commentedon Oct 25, 2022
I don't think there is an issue here. If
pytest-mplis installed, the "figure" tests inastropydon't produce thePytestReturnNotNoneWarning.The issue in
astropy/astropy#13892appears to be that one of the CI jobs which usesremote-data(unskipping the figure tests) does install havepytest-mpl. All the tests at issue use this wrapper: https://github.com/astropy/astropy/blob/8a3cd43d45722dbb2fbc03e63bfef61320ac1b0e/astropy/tests/figures/helpers.py#L8-L44, which apparently does not requirepytest-mpleven though it seems to be using it (https://github.com/astropy/astropy/blob/8a3cd43d45722dbb2fbc03e63bfef61320ac1b0e/astropy/tests/figures/helpers.py#L29-L32).There are two options:
pytest-mplis not installed, then these tests get skipped.pytest-mplas a dependency to the CI jobs which useremote-data.My preference is for option 1.
pllim commentedon Oct 25, 2022
My vote is also 1 since I don't find these tests very useful without this plugin.
WilliamJamieson commentedon Oct 25, 2022
The only thing that those tests do is exercise some of the
astropy.visualizationcode meaning it "tests" that it doesn't raise an error inmatplotlib. But the circle CI (the one that usespytest-mpl) also runs these tests, but actually tests the resulting figures.pllim commentedon Oct 25, 2022
Sure, but CircleCI one is the true purpose of those tests. I think "just see if it crash or not" is partly covered by doctest anyway. Though if you are relying on the job without pytest-mpl to calculate coverage... 💭
pllim commentedon Oct 25, 2022
Then again, (2) isn't a foolproof solution. Anyone running these tests with remote data locally but didn't install pytest-mpl would have the same problem.
astrofrog commentedon Oct 25, 2022
I would be fine with 1
WilliamJamieson commentedon Oct 25, 2022
Alright, here is a weird
pytest-mplissue:pytest-mplinstalledimport pytest_mplfails as expected.pip install pytest-mpland then do aimport pytest_mplit works (whatHAS_PYTEST_MPLdoes).pip uninstall pytest-mpland then donimport pytest_mplit works again. Moreover, the skips for nopytest-mpldo not occur and we get the error frompytestthat we saw before (This is wrt the astropy branch Fix testing forpytest7.2 support astropy/astropy#13892).pip install pytest-mplsolves the failing unit tests.I have to create a completely new environment in order for the
import pytest_mplto start failing again...pllim commentedon Oct 25, 2022
FWIW, I cannot reproduce this problem but I use
condaand you don't. 🤷[-]Returning fig is incompatible with pytest 7.2[/-][+]Returning fig is incompatible with pytest 7.2 (when test uses marker but pytest-mpl not installed)[/+]ConorMacBride commentedon Nov 3, 2022
As already noted, this issue only occurs when pytest-mpl is not installed. I've opened a PR to close this issue. It adds the following to the docs: