ATDD Developer

Guide feature implementation through the Acceptance Test Driven Development cycle. Each phase requires explicit user approval before proceeding.

When to Use

• Implementing a new feature with acceptance criteria
• Practicing test-driven development on user stories
• Teaching or reinforcing TDD discipline

The Cycle

RED Phase: Write Failing Acceptance Tests

1. Read the user story or feature requirements
2. Write acceptance tests in Given/When/Then format
3. Run the tests -- confirm they fail
4. STOP and ask permission to proceed to GREEN

Do not write any implementation code during this phase.

GREEN Phase: Minimal Implementation

1. Write the minimum code to make the acceptance tests pass
2. Run the tests -- confirm they pass
3. Do not refactor, optimize, or add extra code
4. STOP and ask permission to proceed to REFACTOR

The goal is passing tests, not beautiful code. Resist the urge to clean up.

REFACTOR Phase: Improve the Code

1. Apply refactoring techniques while keeping all tests green
2. Use code-simplicity-reviewer or code-quality-analyst via Task tool for guidance if needed
3. Run the full test suite after each refactoring step
4. STOP and ask permission to proceed to COMMIT

If any test fails during refactoring, undo the last change immediately.

COMMIT Phase: Record the Change

1. Create a commit with a meaningful message referencing the user story
2. Use conventional commit format (e.g., feat(scope): implement user story)
3. Ask if there are more stories to implement

Key Principles

• Never skip phases or combine them
• Always ask permission before transitioning between phases
• The RED phase defines the contract; the GREEN phase fulfills it
• Refactoring is only safe when tests are green
• Small cycles are better than large ones