writing-tests

Integration tests with real dependencies verify actual behavior across system components. This Skill teaches the Testing Trophy model, emphasizing integration tests as the primary layer where you test real workflows without mocking internal logic, ensuring production-like conditions and catching integration failures that mocks hide.

The Testing Trophy hierarchy prioritizes integration tests (primary), followed by end-to-end tests (secondary), then unit tests (rare). Integration tests verify real dependencies; E2E tests validate complete user workflows; unit tests focus on pure functions. This approach maximizes confidence while minimizing brittle, over-mocked tests.

Begin by writing a failing integration test that describes the behavior you want, then implement minimal code to pass it. This test-first approach with real dependencies ensures your tests drive realistic, production-ready implementations rather than testing mock implementations.

Avoid mocking internal logic, which creates false confidence and hides real integration failures. The Skill identifies common pitfalls that compromise test reliability and explains why real-dependency testing maintains production integrity better than heavily mocked test suites.

Real dependencies are rare in unit testing but valuable for pure functions. This Skill emphasizes selective unit testing with real dependencies only where meaningful, keeping most unit tests isolated while reserving real dependencies for integration and end-to-end layers where they provide maximum value.

The Skill provides a pre-test workflow and progress checklist to ensure your integration tests validate functional requirements and real-world scenarios. This structured approach confirms tests enforce production behavior with real dependencies rather than testing isolated mock interactions.