MAINT: Remove astropy.test(), should use pytest directly

[MridulS]

This PR addresses one of the points brought forward in #16177.

This removes astropy.test(), this does not deprecate/remove TestRunner. We can do a deprecation too (astropy.test()) if folks think this is a tad bit aggressive for downstream code 😅 . We can go down the sunpy route too and add a direct call to pytest.main from astropy.test but I would argue let's keep the testing separate from final user install. A user shouldn't really ever worry about installing a broken astropy wheel. It should be caught in the CI first! If a user is doing a source build install I think it's fair to assume they are comfortable with calling pytest directly from command line.

This is the first step towards removing TestRunner. There is a lot of code in TestRunner that hasn't been touched in 10 years and things will only keep on evolving in pytest to play maintenance catchup 😅

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[pllim]

Thanks!

I think this still needs a change log, because we had advertised astropy.test() in RC testing in the past, for that one person who wonders why 6.1rc testing is different...

[pllim]

p.s. When requested changes are addressed, this also would need a "Extra CI" label.

[saimn]

So this would imply that RC testing should be done with pytest --pyargs astropy ?

[MridulS]

So this would imply that RC testing should be done with pytest --pyargs astropy ?

Yes, assuming all the paths are fine, this should work just fine. I tried this out with https://github.com/astropy/astropy/wiki/v6.0-RC-Testing and it worked fine with pytest --pyargs astropy --remote-data

[mhvk]

A few small further comments...

[mhvk]

This is doubled up. This line and l.308 should be combined into

be included by running ``pytest --remote-data=any``.

[mhvk]

This is a bit out of date in general, since we now suggest to use tox. I'd either skip the example and go straight to For more details on... or, perhaps better, rewrite as,

   changes do not break existing code, by running the Astropy tests,
   e.g., by running::

      tox -e test

   For more details on running ...

[mhvk]

Here, the changes are good as is, since we've not installed from source.