This Claude skill provides a comprehensive Test-Driven Development (TDD) framework centered on the Red-Green-Refactor cycle. It streamlines the software engineering process by enforcing a 'test-first' methodology, which significantly improves code quality, ensures high test coverage, and reduces technical debt during both new feature development and bug fixing.
Use Cases
New Feature Development: Use the Red-Green-Refactor cycle to define software behavior through tests before implementation, ensuring code aligns perfectly with requirements.
Bug Fixing and Regression Testing: Reproduce reported issues by writing a failing test first, then implementing the fix to ensure the bug is resolved and won't reappear.
Codebase Refactoring: Safely improve internal code structure and readability by relying on the existing test suite to maintain functional integrity during the 'Refactor' phase.
AI-Augmented Programming: Implement multi-agent workflows where different AI roles handle test generation, implementation, and optimization to create a self-verifying development loop.
name
tdd-workflow
description
Test-Driven Development workflow principles. RED-GREEN-REFACTOR cycle.
allowed-tools
Read, Write, Edit, Glob, Grep, Bash
TDD Workflow
Write tests first, code second.
1. The TDD Cycle
🔴 RED → Write failing test
↓
🟢 GREEN → Write minimal code to pass
↓
🔵 REFACTOR → Improve code quality
↓
Repeat...
2. The Three Laws of TDD
Write production code only to make a failing test pass
Write only enough test to demonstrate failure
Write only enough code to make the test pass
3. RED Phase Principles
What to Write
Focus
Example
Behavior
"should add two numbers"
Edge cases
"should handle empty input"
Error states
"should throw for invalid data"
RED Phase Rules
Test must fail first
Test name describes expected behavior
One assertion per test (ideally)
4. GREEN Phase Principles
Minimum Code
Principle
Meaning
YAGNI
You Aren't Gonna Need It
Simplest thing
Write the minimum to pass
No optimization
Just make it work
GREEN Phase Rules
Don't write unneeded code
Don't optimize yet
Pass the test, nothing more
5. REFACTOR Phase Principles
What to Improve
Area
Action
Duplication
Extract common code
Naming
Make intent clear
Structure
Improve organization
Complexity
Simplify logic
REFACTOR Rules
All tests must stay green
Small incremental changes
Commit after each refactor
6. AAA Pattern
Every test follows:
Step
Purpose
Arrange
Set up test data
Act
Execute code under test
Assert
Verify expected outcome
7. When to Use TDD
Scenario
TDD Value
New feature
High
Bug fix
High (write test first)
Complex logic
High
Exploratory
Low (spike, then TDD)
UI layout
Low
8. Test Prioritization
Priority
Test Type
1
Happy path
2
Error cases
3
Edge cases
4
Performance
9. Anti-Patterns
❌ Don't
✅ Do
Skip the RED phase
Watch test fail first
Write tests after
Write tests before
Over-engineer initial
Keep it simple
Multiple asserts
One behavior per test
Test implementation
Test behavior
10. AI-Augmented TDD
Multi-Agent Pattern
Agent
Role
Agent A
Write failing tests (RED)
Agent B
Implement to pass (GREEN)
Agent C
Optimize (REFACTOR)
Remember: The test is the specification. If you can't write a test, you don't understand the requirement.
