Agent skill

tdd

Guide Test-Driven Development using Kent Beck's Red-Green-Refactor cycle. Use when writing tests, implementing features via TDD, or following plan.md test instructions.

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npx add-skill https://github.com/majiayu000/claude-skill-registry/tree/main/skills/data/tdd

SKILL.md

INSTRUCTIONS

Follow Kent Beck's TDD and Tidy First principles using the three-phase workflow:

  1. RED - /tdd:red - Write ONE small failing test
  2. GREEN - /tdd:green - Make it pass with minimal code, then commit
  3. REFACTOR - /tdd:refactor - Improve structure without changing behavior, commit each step

Workflow Pattern

/tdd:red → write failing test → /tdd:green → pass test → /git:commit
                                                              ↓
        ← next feature ← /tdd:red ← satisfied? ← /tdd:refactor (repeat as needed)

Core Principles

  • One test at a time: Each RED adds exactly ONE failing test
  • Minimal code: GREEN phase writes just enough to pass
  • Never skip REFACTOR: Every TDD cycle must complete all three phases
  • Tidy First: Separate structural changes (refactor) from behavioral changes (feat/fix)
  • Small commits: Commit after GREEN, commit after EACH refactor step

Strategy Selection (GREEN Phase)

Confidence Strategy Use When
Low Fake It Return constant, generalize later
High Obvious Implementation Solution is clear
Generalizing Triangulation Add test to break a fake

Quality Standards

  • Eliminate duplication between test and production code
  • Express intent through clear naming
  • Keep methods small and focused
  • Run ALL tests after EVERY change

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