What problem does it solve? Code written without tests breaks silently during refactors, and bug fixes without reproduction tests often fail to address the real issue. This Skill enforces a disciplined test-first workflow so every behavior change is proven by a failing test before implementation begins. ## Core Features & Use Cases - Red-Green-Refactor Cycle: Write a failing test first, implement the minimal code to pass, then refactor with tests as a safety net. - Prove-It Pattern for Bug Fixes: Reproduce any reported bug with a failing test before attempting a fix, guaranteeing the fix actually works. - Testing Best Practices: Guidance on the test pyramid, DAMP vs DRY in tests, state-based assertions over mocks, and anti-patterns like testing mock behavior or adding test-only methods to production code. - Use Case: A bug report arrives saying completing a task doesn't set its timestamp. Write a failing test that asserts completedAt is set, watch it fail, implement the fix, and confirm the test passes with no regressions. ## Quick Start Ask the agent to implement a new feature or fix a bug using test-driven development, writing a failing test before any production code.
