add pre-commit config

[jakkdl]

It bit me a bunch of times that I didn't run tox before pushing minor changes, and tox -e check takes 13s on my system, so I've gradually recreated all the functionality from it in pre-commit + some other checks. So at this point it might be worth removing tox -e check entirely and transitioning the CI to use pre-commit as well. If you approve of the idea I'll implement the necessary gh CI changes as well & clean up tox.ini.

(though it currently won't pass until #87 is merged)

TODO:

• [x] Go through https://github.com/HypothesisWorks/hypothesis/blob/226028dcf62b7c7a239574af6f5d69559be0febc/requirements/tools.in#L5-L19 and crib any nice ones.

[Zac-HD]

Sounds good to me; mark ready-to-review when... you know... and I'll be happy to merge.

[jakkdl]

I added https://pre-commit.ci/ to my fork, and it now passes on my mirror PR over there: https://github.com/jakkdl/flake8-trio/pull/1

The largest issue was that pyright requires internet connectivity to run, which the pre-commit ci does not support

There's a couple options to get around that:

• Don't run pyright in pre-commit, but have a tox action for it. I'd prefer not to do this, since I want local pre-commit hooks to still run pyright when committing.
• [current solution] skip pyright when run in ci, but have a separate tox environment that runs pre-commit run pyright --all-files. This environment is not included in the default envlist.
  • One downside is that pre-commit will still initialize all hook environments, even if only a single hook is specified, so there's a slight time penalty here.
  • This will necessarily have to check all files (unless the modified file list is piped from the gh ci action into tox somehow) so will be slower - but this is probably an upside since an unmodified file can depend on a type specified in a modified file.
• Use https://pre-commit.ci/lite.html instead, so pre-commit is run as a GH action. Then it will have internet connectivity, but losing out on speed and automatic PR's that update hooks.
• Use mypy instead of pyright :wink: (idk why you went with pyright from the beginning actually, but since I've had mypy enabled in my editor since previously it runs perfectly fine in mypy as well - though not with --strict (but most of those are function signatures not having -> None which pyright doesn't require so it's been inconsistently applied)

Various other considerations for this, or future PR's, or never:

• Run minimal tox from pre-commit, so developers (me) don't accidentally push code with broken tests. Don't think it happens enough to bother figuring out the piping.
• Don't run tests with coverage on any platform but py311-flake8_6. Running with coverage slows down considerably, and means extra # noqa's (I've hacked together some ugly aliases that mostly solves this locally)
• flake8-eradicate still doesn't work with flake8-6, and I haven't found a way to tell pre-commit to exclude specific hook id's from autoupdating, so with the full CI service we'll likely have it nagging us that flake8 is out of date.
• Do we want to disable autofix_prs? I haven't used pre-commit ci enough to know how handy vs irritating vs dangerous it is, but noticed that flake8-bugbear has it disabled.
• flake8-bandit prints weird error messages for me: https://github.com/PyCQA/bandit/discussions/725 and with me doing a bunch of illegal stuff in test-flake8-trio it might just make sense to ditch it
  • or run https://github.com/PyCQA/bandit directly

But otherwise I think this should be good for merging

[jakkdl]

rebased on top of main

[jakkdl]

Renamed the check ci action to show that it's now solely for type-checking. I tried doing that previously but failed, but idk what I did different that time.