a2mus/speckit-tdd

Speckit Tdd Skill

TDD Command

This command invokes the agent to enforce test-driven development methodology.

What This Command Does

1. Scaffold Interfaces - Define types/interfaces first
2. Generate Tests First - Write failing tests (RED)
3. Implement Minimal Code - Write just enough to pass (GREEN)
4. Refactor - Improve code while keeping tests green (REFACTOR)
5. Verify Coverage - Ensure 80%+ test coverage

When to Use

Use /tdd when:

• Implementing new features
• Adding new functions/components
• Fixing bugs (write test that reproduces bug first)
• Refactoring existing code
• Building critical business logic

TDD Cycle

RED → GREEN → REFACTOR → REPEAT

RED:      Write a failing test
GREEN:    Write minimal code to pass
REFACTOR: Improve code, keep tests passing
REPEAT:   Next feature/scenario

TDD Best Practices

DO:

• ✅ Write the test FIRST, before any implementation
• ✅ Run tests and verify they FAIL before implementing
• ✅ Write minimal code to make tests pass
• ✅ Refactor only after tests are green
• ✅ Add edge cases and error scenarios
• ✅ Aim for 80%+ coverage (100% for critical code)

DON'T:

• ❌ Write implementation before tests
• ❌ Skip running tests after each change
• ❌ Write too much code at once
• ❌ Ignore failing tests
• ❌ Test implementation details (test behavior)

MANDATORY: Tests must be written BEFORE implementation. Never skip the RED phase.