addy-test-driven-development

Write a test that reproduces the bug first and confirm it fails, then implement the fix and confirm the test passes. Finish by running the repository's full test suite to verify no regressions were introduced.

RED means writing a failing test for the desired behavior, GREEN means writing the minimal code to make it pass, and REFACTOR means cleaning up the implementation while keeping tests green. The cycle repeats for each new behavior.

Prefer real implementations first, then fakes, stubs, and finally mocks as a last resort. Mock only at boundaries where dependencies are slow, non-deterministic, or have uncontrollable side effects like external APIs or email sending.

Skip TDD for pure configuration changes, documentation updates, and static content changes with no behavioral impact. TDD applies whenever logic is implemented, bugs are fixed, or existing functionality is modified.

Over-mocking is the usual cause: tests verify method calls instead of real behavior, so they pass while actual integrations fail. Test state and outcomes rather than interactions, and use real implementations or fakes where possible.

Inspect the build files like package.json, pom.xml, pyproject.toml, go.mod, or Cargo.toml, and prefer checked-in wrappers like ./gradlew or make test. README, CONTRIBUTING, and CI workflows show the commands that actually gate merges.