test-driven-development

SUMMARY

What it does

This Agent Skill provides guidance for test-driven development (TDD). It instructs agents to write a failing test before implementing code, reproduce bugs with tests before fixing them, and use tests as proof of correctness. The skill includes workflows for the TDD cycle (RED-GREEN-REFACTOR), the Prove-It Pattern for bug fixes, guidance on test pyramid and test sizes, best practices for writing tests (state-based assertions, DAMP over DRY, preferring real implementations over mocks, Arrange-Act-Assert, one assertion per concept, descriptive naming), anti-patterns to avoid, browser testing with DevTools, using subagents for complex bug fixes, and verification checklists. It emphasizes discovering the repository's existing test commands and conventions before writing tests. The skill is intended for software development tasks involving logic implementation, bug fixing, or behavior changes, but not for pure configuration, documentation, or static content changes.