{
  "id": "tdd",
  "handle": "tdd",
  "canonicalUrl": "https://bestskillsforclaude.com/en/skills/tdd",
  "language": "en",
  "alternates": {
    "en": "https://bestskillsforclaude.com/en/skills/tdd",
    "es": "https://bestskillsforclaude.com/es/skills/tdd",
    "pt-BR": "https://bestskillsforclaude.com/pt-br/skills/tdd",
    "ja": "https://bestskillsforclaude.com/ja/skills/tdd"
  },
  "category": {
    "id": "engineering-discipline",
    "name": "Engineering discipline"
  },
  "publisher": {
    "name": "Matt Pocock",
    "url": "https://github.com/mattpocock"
  },
  "source": "https://github.com/mattpocock/skills",
  "documentation": null,
  "licenseAsStated": "MIT",
  "runtime": "Claude Code and agents that support the skills CLI",
  "lastReviewed": "2026-08-05",
  "headline": "Which TDD skill should you actually install?",
  "summary": "Two good options, and installing both is the one clear mistake.",
  "verdict": "Matt Pocock's tdd skill drives red, green, refactor one vertical slice at a time, meaning each cycle delivers a thin but complete piece of behaviour. It is lighter than the superpowers version and fits teams that want the discipline without adopting a whole methodology. Choose one of the two, because running both produces contradictory instructions.",
  "bestFor": "Feature work where you want working behaviour end to end early, and a light process.",
  "skipIf": "You already run superpowers, whose test-driven-development skill covers the same ground.",
  "keyTakeaways": [
    "Vertical slices keep the system runnable at every step.",
    "It is lighter than superpowers TDD, which suits teams that do not want a full methodology.",
    "Two TDD skills at once is a conflict, not a belt and braces setup.",
    "The refactor step is the one people skip, and the one that pays."
  ],
  "quickStart": [
    "Install it with the skills CLI from mattpocock/skills, published under MIT.",
    "Define the first slice narrowly enough that it can be finished in one cycle.",
    "Refactor while the tests are green, never while they are red."
  ],
  "sections": [
    {
      "heading": "What it changes in practice",
      "paragraphs": [
        "Slicing vertically means each cycle produces something that runs, rather than a layer that only becomes useful once three more layers exist. With an agent that matters more than usual, because a half built layer cake is impossible to verify.",
        "The narrower the slice, the more useful the cycle. A slice that takes six steps to pass has already stopped being a slice."
      ]
    },
    {
      "heading": "Where it disappoints",
      "paragraphs": [
        "It assumes a test setup that already works. In a codebase where running one test takes minutes, the loop is too slow to hold anyone's discipline.",
        "It also does not decide what to build. Slicing well is a design skill that the process supports but does not supply."
      ]
    }
  ],
  "faq": [
    {
      "question": "How is it different from the superpowers TDD skill?",
      "answer": "It is lighter and slice oriented, while superpowers embeds TDD in a wider methodology with planning and verification skills around it."
    },
    {
      "question": "Can I install both?",
      "answer": "You can, but you should not. They will give the agent conflicting instructions for the same job."
    },
    {
      "question": "What is a vertical slice?",
      "answer": "A thin path through the whole system that actually runs, rather than one complete layer that does nothing on its own."
    }
  ],
  "sources": [
    {
      "label": "mattpocock/skills on GitHub",
      "url": "https://github.com/mattpocock/skills",
      "kind": "repository"
    },
    {
      "label": "Agent skills directory listing",
      "url": "https://skills.sh",
      "kind": "directory"
    }
  ],
  "machineReadable": {
    "markdown": "https://bestskillsforclaude.com/en/skills/tdd/content.md",
    "json": "https://bestskillsforclaude.com/en/skills/tdd/skill.json"
  },
  "disclosure": "Editorial desk review based on the publisher's own repository. Not a security audit, a benchmark or a guarantee of maintenance."
}