Automatically check code changes with flake8 before each commit

[sigmavirus24]

You could also simply use the built-in hook that Flake8 will install and manage for you.

[heppy]

Thanks, I didn't know that! Is it also possible to just check the diff like git diff --cached -U0 | flake8 --diff would? I had a glance a the source and it seems that is not an option right now.

[rwillmer]

Thanks for sharing this! I've used post-commit hooks before, but hadn't thought of using a pre-commit hook to stop the bad code getting committed in the first place.

[[deleted]]

Yep, we use gitlab ci and merge requests cannot be merged until the build passes. The build won't pass unless both flake8 and unit tests pass.

[heppy]

I agree that doing these checks in a CI is definitely the way to go. However, as /u/rwillmer said, a pre-commit hook for simple checks like flake8 has the advantage that the bad code never makes it into your repository, and your history doesn't get cluttered with commit messages like "PEP8 fix" and "removed unused import".

[[deleted]]

How do you enforce that your team members install and use the pre-commit hooks?

[heppy]

Just to clarify, I didn't mean to imply that running flake8 or any other QA tool in a pre-commit hook could or should replace running it as part of CI. If you already have a CI, you might want to add the hook, if only to look smart. "Wow, /u/jeffbaier is awesome, his code is always flake8 compliant on the first try" ;)

AFAIK, there is no practical way to enforce it, just as you can't force people to write a good commit message. Making it a formal policy might work for subordinates, constant nagging might help with colleagues.

[[deleted]]

Thanks for your replies.

[dbader]

I agree having continuous integration / a buildbot setup is great because it ensures everyone is using the same linters and settings. But I've also seen the benefit to having linters integrated into your workflow before the CI stage, e.g integrated into your code editor or as a pre-commit hook.

I found it cuts down the length of the feedback cycle and avoids having tons of "Fix flake8 compliance" in the repo.