Generate summary when (only) `--mpl-generate-summary` passed

[kavanase]

Hi!
This is an incredibly useful package; we use it extensively in our tests for doped and ShakeNBreak; so thank you very much for building and maintaining!

Just a question/suggestion; when running pytest --mpl-generate-summary=html no summary file is created, but it is with pytest --mpl --mpl-generate-summary=html, because the catch here (https://github.com/matplotlib/pytest-mpl/blob/29fd89095ced454e1f82007aeb592268a430aba0/pytest_mpl/plugin.py#L226C1-L230C7) accounts for --mpl, --mpl-generate-path and --mpl-generate-hash-library. As this is one of the commonly used options, maybe it would be good for it to have similar behaviour to --mpl-generate-path, not needing --mpl to also be specified?
(Obvs a 'me' problem, but personally I always forget I also need --mpl when trying to use the summary option, as I don't use it when generating the images --mpl-generate-path, and takes me a little while to figure out why it's apparently not working).

Maybe something like checking if any "mpl-generate" option has been specified could be used here?

[ConorMacBride]

Hi @kavanase! Thanks a lot for the kind words; great to hear pytest-mpl is useful in doped and ShakeNBreak! Apologies for the delay in replying.

I agree the behaviour is confusing, but I don't think we should change it. Per the docs, the plugin is only enabled via --mpl (run tests), --mpl-generate-path (generate baseline images), or --mpl-generate-hash-library (generate baseline hash library), and the summary option is a config setting that applies once the plugin is enabled by one (or more) of those flags. So the current logic is intentional, even if not very discoverable.

That said, I fully agree the option naming/configuration is inconsistent, and we'll look at what can be cleaned up or deprecated for a future pytest-mpl v1.0.0 while trying to avoid breaking changes. Thanks again for the suggestion and for using the package!

[kavanase]

Ok fair enough! Thanks for following up!