CI: coverage combining is broken

[neutrinoceros]

Been seeing this error consistently lately

Error: No .coverage file was found in the root directory, this is now a requirement for uploading coverage to Codecov. See the documentation for more information: https://github-actions-workflows.openastronomy.org/en/stable/tox.html#coverage
No data to report.
Error: Process completed with exit code 1.

this was previously reported at #406 (comment), but the suggested patch, included in #397, clearly doesn't fix it by itself.

I already tried a couple approaches to address this:

• DEP: upgrade minimal requirement on coverage.py and leverage auto combining #412
• DEP: set a temporary upper bound to coverage (<7.14.0) #413

none of it worked, which means I don't currently understand the problem. My working hypothesis was that pytest-cov didn't play nicely with recent versions of coverage (specifically 7.14.0 and later), because combination is now implied by reporting commands, and combined files are implicitly deleted by default.

[astrofrog]

Is this not deliberate? #397 (comment)

[neutrinoceros]

Oh. I wasn't aware, nor have I seen this approach anywhere I can recall. Feel free to close then.

[Cadair]

I'm not entirely clear what the problem is here? If you use pytest-cov it automatically combines the coverage db files, and if you configure it to write to the dir where the workflows expect everything is fine? Are you having this error with pytest-cov or not?

[neutrinoceros]

To be clear, this report was entirely about CI in this repo. I wrote this report before @astrofrog clarified that this job was expected to fail. Now I don't think there's anything left to fix, so I'll close it now.

[Cadair]

ooooh, ok.