sds / overcommit / 13043089062

91%

master: 91%

push

github

Add `-diff` cli option for running precommit hooks against diffs (#860)

For example, running `overcommit --diff main` from a feature branch will
run pre-commit hooks against the diff between the two branches.

I was able to very easily leverage existing code for the bulk of the
feature - this is mainly just adding the cli option, a hook context to
do the execution and some tests based on the existing `--run-all` test.

---

For background, my team is responsible for a couple of really old,
really large rails apps. Getting them completely in compliance with our
various linters is a huge task that isn't getting done anytime soon
(things are funky to the point that we've even observed breakages with
"safe" auto-correct functions).

I introduced/started heavily encouraging overcommit so that we at least
don't add _new_ linting offenses and things will naturally improve over
time. It's been great, but offenses still slip through though here and
there, especially with juniors who might be getting away with not having
a local install (and/or abusing `OVERCOMMIT_DISABLE=1`).

An option like this would allow me to leverage the very useful "only
apply to changed lines" logic within a ci environment and help enforce
my desired "no new linting offenses" policy.

34 of 34 new or added lines in 4 files covered. (100.0%)

3229 of 3548 relevant lines covered (91.01%)

2006.13 hits per line