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The TDD skill

TDD is part of Matt Pocock's engineering skills. Its job is to run red-green test-driven development, with tests only at seams you agreed on first. It loads on its own when a request matches its description, and you can also call it by name.

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When the agent reaches for it

The agent keeps every installed skill's description in view and loads the full instructions when a request matches. This is the description it reads:

Test-driven development. Use when the user wants to build features or fix bugs test-first, mentions "red-green-refactor", or wants integration tests.

What it asks of the agent

Agents write tests easily and write bad ones just as easily. This skill is the reference that keeps the red-green loop honest. Tests go through public interfaces and read like a specification. Before writing any, the agent names the seams it plans to test and gets your agreement, so effort lands on the paths that matter.

  • Implementation-coupled tests, which break on a refactor when behavior has not changed, are out.
  • Tautological tests, which recompute the expected value the way the code does, are out.
  • Writing every test first and every implementation after is out. One seam, one test, one change per cycle.

What the instructions cover

The sections of its SKILL.md, in order.

  • What a good test is
  • Seams: where tests go
  • Anti-patterns
  • Rules of the loop

What ships with it

Besides SKILL.md, the folder carries these. The agent opens them only when a step in the instructions calls for one.

  • agents/ 1 file · 87 B
  • mocking.md 1 KB
  • tests.md 2 KB

Install the TDD skill

In Claude Code, run this in a session. It comes from the publisher's own instructions.

Claude Code 
/plugin install mattpocock-skills

License: MIT.

In Longwave, add Engineering Skills from the marketplace. It installs all 37 of its skills, and your Claude Code, Codex and OpenCode threads can use them.

Questions people ask

How do I install the TDD skill?

In Claude Code, run /plugin install mattpocock-skills. In Longwave, add Engineering Skills from the marketplace, and its skills reach your Claude Code, Codex and OpenCode threads.

When does the agent use the TDD skill?

When a request matches its description. The agent keeps only the name and description of each installed skill in view, and reads the full instructions when a task fits. You can also ask for it by name.

Use your skills in every harness.

Longwave installs a skill collection once, and your Claude Code, Codex and OpenCode threads can all use it.

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