Why does the skill require the test to fail before I write code?

Watching a test fail (the RED phase) proves that the test is actually checking for the missing feature or bug. If a test passes immediately, it isn't testing anything new, or it's testing the wrong thing.

Can I use this for existing projects without tests?

Yes. When modifying existing code, the skill helps you write tests for the current behavior or the new desired behavior first, bringing TDD discipline to legacy projects.

How does this skill handle bug fixes?

For every bug, the skill guides you to write a failing test that reproduces the issue. Only after the test fails for the expected reason do you write the minimal code to fix it.

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

The Iron Law mandates that no production code is written without a failing test first. If code is written before the test, this skill advises deleting it and starting over to ensure the test truly verifies the requirement.

Test-Driven Development (TDD)

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

bydarthmolen

Security & Testing

Enforces a strict Red-Green-Refactor workflow to ensure high-quality, verified production code through failing tests.

About

This skill transforms Claude into a disciplined TDD practitioner, adhering to the 'Iron Law' of writing failing tests before any production code. It guides the development process through the complete Red-Green-Refactor cycle, ensuring that every feature, bug fix, or refactoring effort is backed by automated verification. By emphasizing behavior over implementation and mandating that tests fail correctly before implementation begins, this skill helps developers eliminate technical debt, discover edge cases early, and maintain high confidence in their codebase.

Key Features

Detection and prevention of common TDD shortcuts and rationalizations
0 GitHub stars
Mandatory verification of test failure reasons to prevent false positives
Minimalist implementation guidance to pass tests without over-engineering
Support for behavior-driven testing over implementation-heavy mocking
Strict enforcement of the Red-Green-Refactor development cycle

Use Cases

Developing new features with systematic verification and clear intent
Refactoring complex logic with the safety net of existing green tests
Fixing bugs by creating reproducible failing tests before applying code changes

About

Key Features

Detection and prevention of common TDD shortcuts and rationalizations
0 GitHub stars
Mandatory verification of test failure reasons to prevent false positives
Minimalist implementation guidance to pass tests without over-engineering
Support for behavior-driven testing over implementation-heavy mocking
Strict enforcement of the Red-Green-Refactor development cycle

Use Cases

Developing new features with systematic verification and clear intent
Refactoring complex logic with the safety net of existing green tests
Fixing bugs by creating reproducible failing tests before applying code changes