Red-Green Loop
Test-first development, one failing test at a time.
What it does
Test-driven development. Use when the user wants to build features or fix bugs test-first, mentions "red-green-refactor", or wants integration tests.
Install in under a minute
Mac or Linux, after you download
unzip red-green-loop.zip -d ~/.claude/skills/Windows PowerShell
Expand-Archive red-green-loop.zip -DestinationPath $HOME\.claude\skills- Start a new Claude Code session so it sees the skill.
- Ask in plain words, for example: "Use Red-Green Loop on this project."
- Unzip the download, then zip just the red-green-loop folder if your computer added an extra folder.
- In Claude.ai, open Settings, then Capabilities, and upload it under Skills.
- Turn the skill on and ask Claude to use it.
Red-Green Loop uses the open SKILL.md format, so it also works in agents like Cursor, Gemini CLI, GitHub Copilot and Codex. Copy the red-green-loop folder into that agent's skills folder, for example .cursor/skills/ or .github/skills/ in your project.
What's inside
The 4 main sections of the SKILL.md, in order.
- What a good test is
- Seams: where tests go
- Anti-patterns
- Rules of the loop
In the download: agents/openai.yaml, LICENSE, mocking.md, NOTICE.md, SKILL.md, tests.md
Credit and license
Red-Green Loop is a renamed, packaged copy of tdd by Matt Pocock (github.com/mattpocock/skills), used under the MIT license. The license and a list of changes ship inside the download.
Questions
Does Red-Green Loop work in Claude.ai, not just Claude Code?
Yes. In Claude.ai, upload the red-green-loop folder as a zip in Settings under Capabilities. It also works in other agents that support Agent Skills, like Cursor, Gemini CLI and GitHub Copilot.
What do I get?
A zip with the red-green-loop folder: its SKILL.md (1,536 words) and its license files. One payment, instant download.
Who made Red-Green Loop?
It's a renamed, packaged copy of tdd by Matt Pocock, used under the MIT license. The license and a list of changes ship inside the download.