review-test-coverage_skill

Overview

This skill performs a test coverage-focused code review to find gaps in unit and integration tests, edge cases, and test quality. It highlights missing critical paths, incomplete cases, and maintainability issues to improve confidence in the codebase. The report prioritizes findings so teams can act on the highest-risk gaps first.

How this skill works

The skill inspects source and test files to verify that public functions and API endpoints have corresponding tests, and that error and edge conditions are exercised. It evaluates test quality: independence, naming, flakiness risks, and proper use of mocks and fixtures. Finally, it categorizes findings into Missing, Incomplete, Quality, or Enhancement priorities for actionable follow-up.

When to use it

• Before a release to ensure critical flows are covered
• During pull request reviews to catch missing tests early
• When adding new public APIs, modules, or services
• When diagnosing flaky CI failures or unclear test coverage
• During refactoring to ensure behavior remains validated

Best practices

• Require unit tests for all public functions and boundary values (0, -1, MAX, empty, null).
• Write integration tests for end-to-end flows and database/external service interactions.
• Keep tests independent: avoid shared mutable state and ensure proper setup/teardown. Use fixtures and helpers to reduce duplication.
• Make assertions meaningful: verify outputs and side effects, not just absence of exceptions.
• Avoid over-mocking critical paths; prefer integration tests where external behavior matters. Test error and retry behavior explicitly.

Example use cases

• Review a pull request that adds a new module to ensure all public functions have unit tests and edge cases covered.
• Audit a legacy repository to identify untested critical endpoints and missing database interaction tests.
• Investigate recurring flaky tests to find timing, ordering, or external dependency causes and propose fixes.
• Assess test suite maintainability during a refactor to ensure tests rely on behavior, not implementation details.
• Verify retry and timeout logic by adding tests for failure and recovery scenarios.