pre-commit-hook.md

pytest-mrt as a pre-commit hook

Run static migration analysis before every commit — catches unsafe patterns before they even reach CI.

Setup

1. Install pre-commit:

pip install pre-commit

2. Add to .pre-commit-config.yaml:

repos:
  - repo: local
    hooks:
      - id: mrt-check
        name: Migration safety check
        language: system
        entry: mrt check
        args: [alembic/versions/, --strict]
        files: ^alembic/versions/.*\.py$
        pass_filenames: false

For Django:

repos:
  - repo: local
    hooks:
      - id: mrt-check-django
        name: Django migration safety check
        language: system
        entry: mrt check
        args: [myapp/migrations/, --strict]
        files: ^.*/migrations/.*\.py$
        pass_filenames: false

3. Install the hook:

pre-commit install

4. Test it:

pre-commit run mrt-check --all-files

What it does

Every git commit that touches a migration file will trigger mrt check:

Check Migration safety check.......................................Failed
- hook id: mrt-check
- exit code: 1

╭──────────┬────────────────────────┬───────┬──────┬──────────────────────────────────────╮
│ Revision │ Pattern                │ Sev   │ Line │ Message                              │
├──────────┼────────────────────────┼───────┼──────┼──────────────────────────────────────┤
│ 0042     │ DROP COLUMN in upgrade │ error │   18 │ Data permanently lost on rollback    │
╰──────────┴────────────────────────┴───────┴──────┴──────────────────────────────────────╯
1 error(s), 0 warning(s)

The commit is blocked until the issue is resolved.

Note

The pre-commit hook only runs static analysis (no database needed). For full rollback verification, add the dynamic-check job to your CI pipeline. See github-actions.yml in this directory.