Can this skill be used for legacy codebases?

Yes, it is highly effective for improving legacy code by adding tests for new features or bug fixes, gradually increasing the overall test coverage and stability.

How does the Red-Green-Refactor cycle work?

First, you write a failing test (Red). Second, you write the minimal code necessary to make the test pass (Green). Finally, you clean up the code while keeping the tests passing (Refactor).

Why is watching a test fail (Verify RED) mandatory?

Watching a test fail proves that the test actually checks the intended behavior. If a test passes immediately, it may be testing the wrong thing or existing functionality.

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

The Iron Law states that no production code should be written without a failing test existing first. If code is written before the test, it must be deleted and rewritten test-first.

Test-Driven Development

Name: Test-Driven Development
Author: julianromli

byjulianromli

•

Security & Testing

Enforces a rigorous Red-Green-Refactor workflow to ensure every line of production code is backed by a failing test.

The Test-Driven Development (TDD) skill transforms how Claude approaches software construction by mandating a test-first philosophy. By strictly adhering to the 'Iron Law'—no production code without a failing test first—this skill ensures that software behavior is verified, predictable, and maintainable. It guides the AI through the cycle of writing minimal tests, watching them fail, implementing the simplest possible solution, and refactoring with confidence, ultimately reducing technical debt and preventing regressions in complex codebases.

Key Features

0112 GitHub stars

02Strict Red-Green-Refactor cycle enforcement

03Mandatory verification of failing test states to prevent false positives

04Guidance on writing minimal, behavior-focused implementation code

05Structured refactoring protocols to maintain code quality after passing tests

06Comprehensive verification checklists for feature and bugfix completion

Use Cases

01Safely refactoring existing code by establishing a verified test baseline

02Building new features with high reliability and automated documentation

03Reproducing and fixing bugs with regression test coverage

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add julianromli/opencode-template test-driven-development

For use in Claude.ai and ChatGPT

Download Skill