The tdd skill guides developers through test-driven development using a red-green-refactor loop, emphasizing behavior-driven tests through public interfaces rather than implementation details. It's designed for developers building features or fixing bugs who want to practice TDD, and it solves the problem of writing brittle tests that break during refactoring by teaching vertical slicing (one test-implementation cycle at a time) instead of writing all tests upfront. The skill prioritizes integration-style tests that read like specifications and survive code changes because they verify what the system does, not how it does it internally.
npx skills add https://github.com/mattpocock/skills --skill tdd