Setting up Matt Pocock’s TDD skill

The TDD skill provides working rules for a coding agent; it does not replace a test runner or domain acceptance. The official detail page at [skills.sh/mattpocock/skills/tdd](https://skills.sh/mattpocock/skills/tdd) describes the individual skill. Its complete source is available in the [mattpocock/skills repository](https://github.com/mattpocock/skills), specifically at skills/engineering/tdd/SKILL.md.

Install the individual skill

The product page gives this command for the individual skill:

npx skills add https://github.com/mattpocock/skills --skill tdd

It installs only tdd from the collection. Before running it, the team should check which project directory the selected tool writes to and read the current source. That keeps the instructions the agent will receive traceable.

Use the Claude Code plugin

For Claude Code, the repository names this official plugin route:

claude plugins install mattpocock-skills

This route concerns the plugin package rather than only the individual installation. Reload Claude Code or the relevant session after installing if the client does not recognize new skills immediately. The right path depends on whether a project needs only TDD or a broader collection of skills.

Agree before the first test

The skill asks teams to agree public test boundaries, its “seams,” before the first test. Record whether a feature is tested through an HTTP response, CLI, UI, or public class API. Read available CONTEXT.md files and architecture decisions so test names use the domain’s language. Then begin with one observable behavior and an expected result from the specification, not a check of private methods.

Work through red and green

First watch the test fail for the expected reason. Then implement only the minimum that makes it pass. Repeat that small vertical step for the next behavior instead of writing a broad suite for an assumed architecture first. Refactoring and review follow verified changes. Every change should rerun the project’s usual test command.