test-driven-development
Drives development with tests using the red-green-refactor loop. Use when implementing any logic, fixing any bug, or changing any behavior. Use when you need to prove that code works, when a bug report arrives, or when you're about to modify existing functionality. Use when asked to add tests to a function, fix a bug in it or change its behavior, even when the code is pasted inline and the request does not mention tests.
Install
With your agent
Install OMGSkills skill "addyosmani/agent-skills:test-driven-development" into this agent's normal skills directory: call the OMGSkills MCP get_install_plan tool for your agent and run the script it returns (it installs only the pinned commit and verifies SKILL.md), and stop if MCP or the pin is unavailable. Do not overwrite or change existing skills without asking me.
Manual command
git clone https://github.com/addyosmani/agent-skills /tmp/agent-skills && ln -s /tmp/agent-skills/skills/test-driven-development ~/.claude/skills/test-driven-developmentFrom README
Test-Driven Development Overview Write a failing test before writing the code that makes it pass. For bug fixes, reproduce the bug with a test before attempting a fix. Tests are proof — "seems right" is not done. A codebase with good tests is an AI agent's superpower; a codebase without tests is a liability. When to Use Implementing any new logic or behavior Fixing any bug (the Prove-It Pattern) Modifying existing functionality Adding edge case handling Any change that could break existing behavior When NOT to use: Pure configuration changes, documentation updates, or static content changes that have no behavioral impact. Related: For browser-based changes, combine TDD with runtime verification using Chrome DevTools MCP — see the Browser Testing section below. Discover the Stack First The TDD cycle is universal; the commands are not.