test-driven-development

name	test-driven-development
description	Write the test first, watch it fail, write minimal code to pass
version	3.2.0
category	testing
author	Jesse Vincent
license	MIT
source	https://github.com/obra/superpowers-skills/tree/main/skills/testing/test-driven-development
progressive_disclosure	{"entry_point":{"summary":"Enforce test-first development with strict RED/GREEN/REFACTOR cycle. Never write implementation before failing test.","when_to_use":"When implementing any feature or bugfix, before writing implementation code. Always for new features, bug fixes, refactoring, and behavior changes.","quick_start":"1. Write failing test 2. Watch it fail (verify) 3. Write minimal code to pass 4. Watch it pass (verify) 5. Refactor if needed 6. Repeat"},"references":["workflow.md","examples.md","philosophy.md","anti-patterns.md","integration.md"]}
context_limit	800
tags	["tdd","testing","red-green-refactor","test-first"]
effort	high

Test-Driven Development (TDD)

Overview

Write the test first. Watch it fail. Write minimal code to pass.

Core principle: If you didn't watch the test fail, you don't know if it tests the right thing.

This skill enforces strict test-first development following the RED/GREEN/REFACTOR cycle. Violating the letter of the rules is violating the spirit of the rules.

When to Use This Skill

Always:

• New features
• Bug fixes
• Refactoring
• Behavior changes

Exceptions (ask human partner):

• Throwaway prototypes
• Generated code
• Configuration files

Thinking "skip TDD just this once"? Stop. That's rationalization.

The Iron Law

NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST

Write code before the test? Delete it. Start over.

No exceptions:

• Don't keep it as "reference"
• Don't "adapt" it while writing tests
• Delete means delete

Core Principles

1. RED: Write a failing test first
2. GREEN: Write minimal code to make test pass
3. REFACTOR: Improve code while keeping tests green
4. NEVER: Write implementation before tests

Quick Start

The RED/GREEN/REFACTOR Cycle

RED → Verify RED → GREEN → Verify GREEN → REFACTOR → Repeat

1. RED: Write one minimal test showing desired behavior
2. Verify RED: Run test, confirm it fails for right reason
3. GREEN: Write simplest code to pass test
4. Verify GREEN: Run test, confirm it passes
5. REFACTOR: Clean up while keeping tests green
6. Repeat: Next test for next feature

Cycle Details

RED: Write one minimal test (one behavior, clear name, real code) Verify RED: MANDATORY - watch it fail for right reason GREEN: Write simplest code to pass (no extras) Verify GREEN: MANDATORY - watch it pass, all tests pass REFACTOR: Clean up while keeping tests green (optional)

Navigation