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.
When & Why to Use This Skill
This Claude skill facilitates professional Test-Driven Development (TDD) by enforcing Kent Beck's Red-Green-Refactor cycle. It streamlines the software engineering process by guiding users through writing failing tests, implementing minimal code solutions, and performing systematic refactoring to ensure high-quality, maintainable codebases and reduced technical debt.
Use Cases
- Feature Implementation: Build new software components from scratch using a test-first approach to ensure 100% functional alignment and high code coverage.
- Legacy Code Refactoring: Safely improve existing code structures by applying 'Tidy First' principles, ensuring behavioral consistency through incremental testing and small commits.
- Technical Plan Execution: Systematically follow complex development instructions (such as those in a plan.md) while maintaining strict adherence to professional TDD quality standards.
- Code Quality Optimization: Eliminate duplication and improve code readability by integrating mandatory refactoring phases into the daily development loop.
| name | tdd |
|---|---|
| description | 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. |
INSTRUCTIONS
Follow Kent Beck's TDD and Tidy First principles using the three-phase workflow:
- RED -
/tdd:red- Write ONE small failing test - GREEN -
/tdd:green- Make it pass with minimal code, then commit - 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