| name | tdd-workflow |
| description | Strict Red-Green-Refactor workflow for feature development and bug fixing. Use when the user wants to ensure high-quality, behavior-verified code by writing tests first. |
TDD Workflow
This skill implements a strict TDD approach to building features or fixing bugs, emphasizing behavior verification through public interfaces.
Core Philosophy
- Behavior over Implementation: Tests verify what the system does, not how it does it.
- Public Interfaces Only: Exercise code through public APIs. Tests that break during internal refactoring are likely coupled to implementation and should be revised.
- Vertical Slicing: Use "tracer bullets"—one test, one implementation, repeat. Avoid writing all tests upfront.
Workflow Phases
1. Planning (Mandatory)
Before writing any code:
- Identify the behavior to implement or bug to fix.
- Design the public interface (input/output).
- List and prioritize specific behaviors to be tested.
- Ask: "What should the public interface look like? Which behaviors are most important to test?"
2. The Cycle (Red-Green-Refactor)
Phase A: RED (Write a Failing Test)
- Write exactly ONE test for the next behavior.
- Verify it fails with a relevant error message (not just a syntax error).
Phase B: GREEN (Pass the Test)
- Write the absolute minimal code required to make the test pass.
- Do not anticipate future requirements or add speculative features.
Phase C: REFACTOR (Improve the Code)
- ONLY refactor when in a GREEN state.
- Improve code structure, readability, and performance without changing behavior.
- Run tests after every small refactor step to ensure no regressions.
Checklist
Refer to references/checklist.md for a step-by-step cycle checklist.
