With pre-commit, exits with 1 as return value even with no messages for linters

[akaihola]

When running via pre-commit, even if there is nothing to report from linters, darker seems to provide a 1 as exit code so pre-commit fails.

[WARNING] Unstaged files detected.
[INFO] Stashing unstaged files to [...]
darker...................................................................Failed
- hook id: darker
- exit code: 1
[INFO] Restored changes from [...]

I guess darker just doesn't return anything if there are no problems?

Originally posted by @deadkex in #378 (comment) on 2022-08-30 (Darker 1.5.0)

[akaihola]

I wonder if issue akaihola/graylint#6 and its fix akaihola/graylint#34 affect this now that Darker actually uses Graylint for linting support?

@deadkex could you check whether Darker 2.1.1 with Graylint 1.1.1 fixes this issue?

[akaihola]

I also now tried this on Darker 1.5.0 (from August 2022, accompanied by Black 22.8.0), and if I run darker -L pylint . ; echo $? in a repository which has no linting errors, it does print out a 0.

I didn't try pre-commit, but at least directly from the command line the behavior was correct already at the time of @deadkex's report.

[deadkex]

Hi @akaihola
something i observed back then was that while there are not linting errors - if black has some problems it will provide 1 as exit code even though i turned of black prints & formatting via config. I did not test since quite some time since we decided to switch to CI checks.