# Test Driven Development (agent skill)

> Test Driven Development is an agent skill (a SKILL.md file) from addyosmani/agent-skills. Drives development with tests using the red-green-refactor loop. It works with Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot and OpenCode and has 110,586 GitHub stars across a repository of 13 listed skills.

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. Write a failing test before writing the code that makes it pass.

## Key facts

| Fact | Value |
|---|---|
| Repository | https://github.com/addyosmani/agent-skills |
| Skill path | skills/test-driven-development/SKILL.md |
| Skill name | test-driven-development |
| GitHub stars | 110,586 |
| Installs on skills.sh | 61,316 |
| License | MIT |
| Skills in repo | 13 |
| Plugin marketplace | addy-agent-skills |
| Official | no |
| Works with | Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode |
| Category | Testing & QA |
| Last commit | Oct 13, 2026 |

## When it triggers

- 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.

## Add this skill

### Claude Code

```sh
/plugin marketplace add addyosmani/agent-skills
/plugin install agent-skills@addy-agent-skills
```

In the Claude apps, zip the skill folder and upload it under Customize > Skills > + > Upload a skill (code execution must be on).

### ChatGPT / Codex

```sh
git clone --depth 1 https://github.com/addyosmani/agent-skills.git
cp -r agent-skills/skills/test-driven-development .agents/skills/test-driven-development   # repo; ~/.agents/skills for all projects
```

### Cursor

```sh
git clone --depth 1 https://github.com/addyosmani/agent-skills.git
cp -r agent-skills/skills/test-driven-development .cursor/skills/test-driven-development   # project; ~/.cursor/skills for all projects
```

Sources (checked 2026-10-07): https://code.claude.com/docs/en/skills, https://support.claude.com/en/articles/12512180-using-skills-in-claude, https://learn.chatgpt.com/docs/build-skills, https://cursor.com/docs/context/skills

skills.sh listing: https://www.skills.sh/addyosmani/agent-skills/test-driven-development

---

Canonical page: https://appsgit.com/skills/addyosmani-test-driven-development
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