Ratchet up a coverage.py configuration's fail_under to prevent coverage regressions.

Usable with coverage.py directly, or with pytest-cov.

Intended to be run in pre-commit or CI.

If coverage from the last run does not exceed fail_under at all, coverage run and coverage report will normally fail. Do nothing in that case.

If code coverage of the last test significantly exceeds fail_under, recommend increasing the configured fail_under.

Exits with status 1 when changes to configuration should be made. If --write is passed, also make the changes.

Will not reduce configured fail_under; coverage requirements can only increase.

If fail_under ever reaches 100%, this hook becomes a no-op and can be safely removed.

# .pre-commit-config.yaml

- repo: https://github.com/ellieayla/ratchet-coverage-fail-under
  rev: v1.0.3
  hooks:
    - id: ratchet-coverage
      #args: [--write]  # whether to automatically write pyproject.toml

arguments

• --cov-config PATH - the configuration file, ideally pyproject.toml but defaults to letting coverage.py discover.
• --data-file PATH - the .coverage sqlite database file, if necessary to override from configuration file.
• --threshold PERCENT - recommend a new fail_under that's PERCENT of last run. Pass 100% to ratchet up to last run exactly.
• --write - write recommendation back to pyproject.toml.