Can I use this skill for existing codebases without tests?

Absolutely. It encourages adding tests for new changes or bug fixes in legacy code, gradually improving the test coverage and stability of the project.

Does this skill work for bug fixes?

Yes, for bug fixes, the skill requires writing a test that reproduces the bug (RED), verifying the failure, and then implementing the minimal fix to pass (GREEN).

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

The Iron Law dictates that no production code can be written without a failing test first. If code is written before a test, it must be deleted and started over to ensure the test truly verifies the requirement.

Why is 'Verify RED' a mandatory step?

Verifying the failure ensures that the test is actually testing the missing feature or bug and isn't passing by accident or failing due to a simple syntax error.

Test-Driven Development (TDD)

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

bypyinx

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Security & Testing

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

The TDD skill integrates the rigorous discipline of Test-Driven Development into Claude's coding workflow, mandating that no production code is written without a prior failing test. By following the 'Iron Law' of TDD, it helps developers create more reliable, maintainable, and self-documenting codebases while eliminating technical debt and regressions from the outset. It provides domain-specific guidance on the Red-Green-Refactor cycle, helping Claude distinguish between testing behavior versus implementation and ensuring every code change is minimal, purposeful, and verified.

Key Features

01Strict Red-Green-Refactor cycle enforcement

02Refactoring best practices within a green state

03Minimal production code implementation guidance

04Detailed TDD anti-pattern detection

052 GitHub stars

06Mandatory failure verification (Verify RED)

Use Cases

01Implementing new features with high reliability and zero regressions

02Fixing bugs by reproducing them with failing tests before writing fixes

03Safely refactoring complex logic with continuous test verification

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add pyinx/ceo-skills-plugin tdd

For use in Claude.ai and ChatGPT

Download Skill