What problem does it solve? Developers often write code first and tests later (or never), leading to regressions, unclear requirements, and fragile designs. This Skill enforces the red-green-refactor cycle so every feature starts with a failing test that defines expected behavior before implementation begins. ## Core Features & Use Cases - Red-Green-Refactor Workflow: Guides writing a failing test first, implementing minimal code to pass, then refactoring safely with tests green. - Testing Patterns Library: Covers descriptive test naming, the Arrange-Act-Assert pattern, fixtures, mocking external dependencies, exception testing, and async test handling with pytest. - Verification Checklist: Ensures tests were written before implementation, each test covers one behavior, and no untested code paths remain. - Use Case: When fixing a bug in user registration, write a failing regression test reproducing the bug, implement the minimal fix to make it pass, then refactor the surrounding code while the test suite guards against regressions. ## Quick Start Use the test-driven-development skill to implement a new user registration feature by writing the failing test first, then the minimal code to pass it, then refactoring.
