Some tests accessing matplotlib.axes.Axes.artists fail with Matplotlib 3.5.0b1

[hakonanes]

Specific tests: https://github.com/hyperspy/hyperspy-extensions-list/runs/3551171059?check_suite_focus=true#step:13:1

Don't know why, but this should be fixed. Using matplotlib 3.5 shouldn't break any functionality, just tests.

Solution: In the tests, we should access the patches (artists) from Axes.patches, since that's what they are. And add them to the axes via Axes.add_patch() instead of Axes.add_artist().

[hakonanes]

Again, thanks to @ericpre for running kikuchipy and other HyperSpy extensions against development versions of our dependencies at https://github.com/hyperspy/hyperspy-extensions-list.

[ericpre]

The failure seems to be related with a API deprecation to remove artists in matplotlib 3.5 but as you will know, it should be only warning. Sometimes, it is possible that there is a bug in the deprecation, in which case, it will be good that you report it while matplotlib in still in beta/rc.

[ericpre]

Again, thanks to @ericpre for running kikuchipy and other HyperSpy extensions against development versions of our dependencies at https://github.com/hyperspy/hyperspy-extensions-list.

What would be great to do: hyperspy/hyperspy-extensions-list#13

[hakonanes]

The failure seems to be related with a API deprecation to remove artists in matplotlib 3.5 but as you will know, it should be only warning.

I checked, and neither an error nor a warning is raised by Matplotlib when adding an artist and then accessing Axes.artists... Do you know where the artists are accessible from? I couldn't find any release notes/changelog for Matplotlib v3.5.0b1 either. I'll wait to raise an issue until I know what such a document says which behaviour I'm to expect.

[hakonanes]

Do you know where the artists are accessible from?

Apparently from Axes.patches, which is fine by me. Found it here matplotlib/matplotlib#20895 (comment).

[hakonanes]

However we should change the ax.add_artist() call to ax.add_patch() to make the outcome transparent.

[ericpre]

Sorry, my comments above was slightly misleading - in hyperspy, there are warnings about removing artists!

However we should change the ax.add_artist() call to ax.add_patch() to make the outcome transparent.

Yes, according to https://matplotlib.org/devdocs/api/next_api_changes/deprecations/18216-ES.html, this seems to be on the right track. This and changing how to assert where they are kept!

[hakonanes]

Thanks for the link to the page I was after!

[hakonanes]

Fixed in #445.