Why does the skill insist on watching a test fail first?

Watching a test fail (the Red phase) proves that the test is actually testing the right thing and that it isn't passing by accident or due to existing behavior.

How does this skill handle refactoring?

Refactoring is only permitted after a test passes (the Green phase). This ensures you are cleaning up the code design without accidentally changing its behavior.

When can I skip TDD while using this skill?

TDD is mandatory for all new features and bug fixes. Exceptions are only allowed for throwaway prototypes, generated code, or configuration files after consulting a human partner.

What is the 'Iron Law' of this TDD skill?

The Iron Law dictates that no production code is allowed to be written unless it is preceded by a failing test that specifically addresses the new behavior.

Test-Driven Development (TDD)

Name: Test-Driven Development (TDD)
Author: pedropaulovc

bypedropaulovc

0•

Security & Testing

Enforces a strict Red-Green-Refactor workflow to ensure all production code is verified by failing tests first.

The Test-Driven Development (TDD) skill provides a rigorous framework for Claude to follow the 'Iron Law' of software development: no production code without a failing test first. It guides the AI through the complete Red-Green-Refactor cycle, ensuring that tests are written to define behavior before implementation begins. This approach minimizes over-engineering, prevents regressions, and produces self-documenting codebases where every feature is backed by a systematic verification process. It is an essential tool for developers who prioritize high-quality, maintainable code over quick, unverified hacks.

Key Features

01Mandatory failure verification (Verify RED) to prove test validity

02Minimalist coding principles to prevent over-engineering (YAGNI)

03Refactoring guidance to clean up code while maintaining green states

040 GitHub stars

05Comprehensive test quality guidelines for clear and intent-based testing

06Strict Red-Green-Refactor cycle enforcement

Use Cases

01Safely refactoring complex legacy logic with a protective test suite

02Reproducing and fixing bugs by writing a failing test case first

03Developing new features with automated verification from the start

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add pedropaulovc/personal-marketplace test-driven-development

For use in Claude.ai and ChatGPT

Download Skill