Can no longer run test suite without all the plugins because of warnings

[Cadair]

This includes at least, doctestplus, asdf and remote-data

[dstansby]

Why is this an issue? Is there an instance where one would want to (or expect to) run the test suite without all the test dependencies?

[Cadair]

asdf is one of the things I wouldn't expect to have to be installed to run our tests, also we have code in conftest.py to handle a missing pytest-remotedata, so if that's not something we support anymore we should remove it.

[Cadair]

Also see this fail on #4605 because you can't now run even the non-figure tests without pytest-mpl installed because we have some config option.

[nabobalis]

I guess my question is, what do we want to happen by default?

Do we want for pytest to skip over test that require these plugins (in the same manner want to skip over submodules without deps installed)?

[Cadair]

Maybe this is just expected, but it was jarring to me at least.

[nabobalis]

Sure I think it is a bit jarring to run non-figure tests and have it error since pytest-mpl isn't installed.

I just am unclear on what we would like to be the default behaviour.

[dstansby]

Can we just filter the appropriate warnings in setup.cfg?

[dstansby]

Pretty sure this was fixed in the above PR, feel free to re-open if not the case.

[Cadair]

Some of it but not all of it, I think it will still fail if asdf isn't installed, probably among others.

[dstansby]

I recently ran without asdf installed and it worked fine, and threw a warning at the end of the test run.