What problem does it solve? Developers frequently 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 the agent through writing a failing test, verifying it fails for the right reason, writing minimal code to pass, and refactoring while staying green. - Rationalization Detection: Lists common excuses for skipping TDD ("too simple to test", "I'll test after") with counterarguments, plus red flags that trigger deleting code and starting over. - Testing Anti-Patterns Reference: A companion reference covers testing mock behavior, test-only methods in production classes, incomplete mocks, and mocking without understanding dependencies. - Use Case: When asked to fix a bug where empty emails are accepted, the agent first writes a failing test asserting the rejection, watches it fail, implements the minimal validation, and verifies all tests pass. ## Quick Start Use test-driven development to implement the new retry feature, writing a failing test first and watching it fail before any implementation code.
