What problem does it solve? Developers often write production code first and add tests afterward, which produces tests that pass immediately without proving they can catch bugs. This Skill enforces a strict test-driven development discipline so every feature, bug fix, and refactor is backed by a test that was seen to fail first. ## Core Features & Use Cases - Red-Green-Refactor Cycle: Guides the AI to write a failing test, verify it fails for the right reason, write minimal code to pass, then refactor while keeping tests green. - Anti-Rationalization Rules: Provides a table of common excuses ("too simple to test", "I'll add tests later") with concrete rebuttals, plus red-flag signals that require deleting code and restarting with TDD. - Test Quality Reference: A companion guide (writing-good-tests.md) covering how to name the breakage each test catches, avoid mocking real behavior, derive expected values independently, and run mutation checks. - Use Case: When fixing a bug where empty emails are accepted, the Skill directs writing a failing test asserting the rejection error, verifying the failure, then implementing the minimal validation fix. ## Quick Start Ask the AI to implement a new feature or fix a bug using test-driven development, writing the failing test before any production code.
