check-test-separation

Separating unit and integration tests in Python prevents slow, flaky test suites by maintaining clear test boundaries. This AST-based checker analyzes directory placement, pytest markers, integration-signaling imports, and mock usage to flag improperly mixed tests and report violations.

Yes, you can check test separation on only changed files in a CI pipeline. The checker supports analyzing changed files, specific directories, or single test files, returning a non-zero exit code when error-level violations are found for pre-commit or CI checks.

AST analysis identifies integration tests by inspecting test files for integration-signaling imports, decorator patterns like pytest markers, call patterns, and counting mock usage. It also inspects conftest fixtures to flag unclassified test files and validate directory placement.

The best way to enforce test directory placement under tests/unit/ and tests/integration/ is using an AST-based static analysis checker that flags unclassified test files. This validates directory structure and reports separation violations to maintain clear test boundaries.

Heavy mocking in unit tests indicates mixed integration test logic because excessive mock usage signals complex dependency management that belongs in integration tests. The checker counts mock usage and inspects conftest fixtures to detect these problematic patterns and report violations.