Black pre-commit hook not respecting pyproject.toml exclude config

[jidicula]

Describe the bug
The Black pre-commit hook blocks commits containing staged Python files not respecting Black formatting when those files are in the tool.black exclude path in pyproject.toml. Those files should not be causing the pre-commit hook to fail. When running black --check . at the repo root, the check passes, indicating the issue is specifically with the pre-commit hook.

To Reproduce Steps to reproduce the behavior:

1. Clone this repo containing a minimal reproducible example of this bug.
2. Follow the directions in its README to reproduce the bug.

Expected behavior
Staged changes that are non-compliant with Black in files that are supposed to be ignored by Black should be able to pass the pre-commit check hook.

Environment (please complete the following information):

• Version: 20.8b1
• OS and Python version: macOS 11.2.1 Python 3.7.1

Does this bug also happen on master? To answer this, you have two options:

Yes, see here. However, I could only use the commit at the HEAD of master on the day I tried this out (today, 2021-02-13), since pre-commit does not allow branchnames for the value of rev.

Additional context Add any other context about the problem here.
None

[ichard26]

See #438. The problem is that pre-commit passes the files it wants the Black hook to check directly via the CLI instead of letting Black find them by itself. Files directly passed through the CLI aren't subject to the ---include/--exclude regexes since they only apply to recursively found files and directories. Try using --force-exclude which behaves like --exclude but also applies to files and directories directly given through the CLI.

I hope that helps!

[jidicula]

Thanks @ichard26! I'm still struggling to get this set up though. How should I be passing the path to the --force-exclude option? This is what I currently have and it's still failing the pre-commit hook when I change any Python file in the ignored/ path.

repos:
  - repo: https://github.com/psf/black
    rev: b8c1020b526b488a1a216d9a4d58fc8616b61a99
    hooks:
      - id: black
        language_version: python3
        args:
          - --force-exclude='ignored/'

[ichard26]

repos:
  - repo: https://github.com/psf/black
    rev: b8c1020b526b488a1a216d9a4d58fc8616b61a99
    hooks:
      - id: black
        language_version: python3
        args: [--force-exclude, ignored/]

maybe??? (I don't use pre-commit or YAML syntax enough to be 100% sure)

You could also just use the --force-exclude option via your pyproject.toml config file.

[jidicula]

You could also just use the --force-exclude option via your pyproject.toml config file.

AHA, yes that would be perfect - I much prefer having a SSOT for these configs 😁. Thank you so much, that worked nicely!

For anyone coming across this issue later, this is my tool.black entry in my pyproject.toml that is respected by pre-commit:

exclude = '''
/(
    \.eggs
  | \.git
  | \.venv
  | \.env
  | build
  | dist
  | \.mypy_cache
)\
'''
force-exclude = '''
/(
   ignored                     # files in this dir are ignored by pre-commit
)\
'''

The example is also visible here.

[maxbane]

Hi, I'm sure I'm missing something, but quick question... My pyproject.toml looks like this:

[tool.black]
extend-exclude = '''
^/codebases/external
'''
force-exclude = '''
^/codebases/external
'''

I find that running black . from my shell ignores the external codebases as desired, but when it is run by pre-commit run --all-files, black still modifies the external codebases. This is surprising to me -- do I really need to use two different regexes in these two options for them to have the same effect?