What is the 'Iron Law' in this Claude Code skill?

The Iron Law dictates that no production code should be written without a failing test first. If code is written before a test, the skill mandates deleting that code and starting over to ensure the test truly validates the behavior.

Can I use this TDD skill for existing bug fixes?

Absolutely. For bug fixes, the skill requires writing a test that reproduces the bug (RED), then implementing the fix (GREEN), and finally cleaning up the implementation (REFACTOR).

Does this skill support mocking?

Yes, but it encourages real code over mocks whenever possible. Mocks should only be used when dependencies are unavoidable, ensuring the tests remain focused on actual code behavior rather than mock configuration.

Why is watching a test fail mandatory?

Watching a test fail (the RED phase) is critical because it proves the test is actually testing the intended functionality and is not passing for the wrong reasons, such as pre-existing code or incorrect test logic.

Test-Driven Development (TDD) Mastery

Name: Test-Driven Development (TDD) Mastery
Author: julianromli

byjulianromli

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101

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セキュリティとテスト

Enforces strict Red-Green-Refactor cycles to ensure production-grade code reliability and architectural clarity.

The Test-Driven Development (TDD) skill transforms Claude into a disciplined coding partner that adheres to the 'Iron Law': no production code without a failing test first. By strictly following the Red-Green-Refactor cycle, this skill prevents technical debt, minimizes regressions, and ensures that every piece of logic is verified by automated tests. It is an essential capability for developers who prioritize high-quality, maintainable codebases and want to avoid the common pitfalls of post-implementation testing or manual verification.

主な機能

01Automated verification of minimal code solutions

02Refactoring guidance while maintaining green status

03Anti-rationalization protection to prevent 'test-after' shortcuts

04101 GitHub stars

05Mandatory test failure verification before implementation

06Strict Red-Green-Refactor cycle enforcement

ユースケース

01Refactoring legacy codebases while ensuring no regression errors

02Fixing bugs by reproducing them first with a failing test case

03Implementing new features with 100% confidence and behavior verification

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