test-driven-development

Enforce test-driven development with failing tests before production code.

Updated May 5, 2026

Search Tags:#testing #tdd #red-green-refactor #software-quality #unit-tests #regression-prevention

Ready to run

npx skills add https://github.com/Z43L/zeus-agent --skill test-driven-development-z43l

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: test-driven-development
Source: https://github.com/Z43L/zeus-agent/tree/main/skills/software-development/test-driven-development
Command: npx skills add https://github.com/Z43L/zeus-agent --skill test-driven-development-z43l

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill helps you prevent bugs and regressions by enforcing a test-first workflow where behavior is specified by a failing test before production code is written.

Core Features & Use Cases

RED-GREEN-REFACTOR discipline: write a failing test, implement the smallest change to pass, then refactor safely while keeping tests green.
Strict verification steps: require that you watch tests fail for the expected reason and then pass without regressions.
Anti-rationalization guardrails: detects common TDD bypasses like “tests after,” mock-only verification, or missing coverage for edge cases.

Quick Start

Ask your AI to implement your next feature using strict test-driven-development, ensuring each step runs the specific failing test first and only then writes the minimal code to make it pass.

Frequently Asked Questions about test-driven-development

High-intent search queries and answers about installing and using this skill.

FAQPage Schema

What is test-driven development and how does it prevent software regressions?▼

Test-driven development is a workflow requiring a failing unit test before writing production code. This test-first approach specifies behavior precisely, preventing bugs and regressions by ensuring code changes are always verified by passing tests.

How do I use the red-green-refactor workflow for new features?▼

To use red-green-refactor, write a failing test for the new feature, implement the minimal code change to make it pass, then refactor safely. You must verify the test fails for the expected reason before writing code to ensure strict TDD discipline.

Can I write tests after coding instead of using a test-first approach?▼

Writing tests after coding is strongly discouraged. The Skill includes anti-rationalization guardrails that detect and bypass common TDD shortcuts like 'tests after,' ensuring you strictly enforce the test-first workflow for reliable regression protection.

Does test-driven development work for bug fixes and refactoring existing code?▼

Yes, test-driven development applies to bug fixes, refactoring, and behavior changes. You write a failing test that reproduces the bug or specifies the new behavior, then modify the code until all tests pass without regressions.

What are the limitations of relying on mock-only verification in unit tests?▼

Mock-only verification is a known TDD bypass. The Skill's guardrails detect this and missing edge case coverage, requiring you to watch tests fail for expected reasons and pass via full test-suite verification to ensure actual regression protection.