test-driven-development

What problem does it solve? Developers often write production code first and add tests afterward, which produces tests that pass immediately and prove nothing about correctness. This Skill enforces a strict test-first discipline so every feature and bugfix is backed by a test that was watched failing before implementation. ## Core Features & Use Cases - Red-Green-Refactor Cycle: Guides writing a failing test, verifying it fails for the right reason, writing minimal code to pass, then refactoring while staying green. - Rationalization Detection: Lists common excuses for skipping TDD (e.g., "too simple to test", "I'll test after") and explains why each is invalid. - Testing Anti-Pattern Reference: Covers pitfalls like testing mock behavior, adding test-only methods to production classes, incomplete mocks, and mocking without understanding dependencies. - Use Case: When fixing a bug where an empty email is accepted, write a failing test asserting the rejection error, watch it fail, implement the minimal validation, and confirm all tests pass. ## Quick Start Use the test-driven-development skill to implement this feature by writing a failing test first, then the minimal code to make it pass.