tdd

Execute test-first development with RED-GREEN-REFACTOR cycles to prevent regressions.

1|Updated Mar 17, 2026
One-click install
npx skills add https://github.com/yknothing/prodcraft --skill tdd-yknothing
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: tdd
Source: https://github.com/yknothing/prodcraft/tree/main/skills/04-implementation/tdd
Command: npx skills add https://github.com/yknothing/prodcraft --skill tdd-yknothing

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Writing and maintaining robust software requires a safety net that prevents unnoticed regressions. Test-Driven Development (TDD) enforces a process where tests drive the design, ensuring code is written only to satisfy failing, explicit specifications.

Core Features & Use Cases

  • Failing-First cycles: Write a failing test to specify the desired behavior before coding.
  • RED-GREEN-REFACTOR discipline: Iterate from a minimal implementation to a cleaner design with confidence.
  • Regression protection: Maintain a living specification to guard against future changes.

Quick Start

Start by drafting a failing test that captures the next planned task slice, then implement the simplest code that makes the test pass.

Frequently Asked Questions about tdd

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

FAQPage Schema
What is test-driven development and how does it protect against regressions?▼

Test-driven development is a workflow requiring a failing test before implementation. It shields code from regressions by treating tests as living specifications, ensuring code is written only to satisfy explicit, failing specifications.

How do I start writing code using the RED-GREEN-REFACTOR cycle?▼

Start the RED-GREEN-REFACTOR cycle by drafting a failing test that captures the next planned task slice. Then, implement the simplest code that makes the test pass before refactoring to a cleaner design.

Can I apply test-first development to existing brownfield codebases?▼

Yes, test-first development is widely applicable to both greenfield and brownfield work. It proves contract behavior, safety checks, and coexistence boundaries across discovery through integration phases.

When should I use unit testing to drive software design instead of writing tests after implementation?▼

Use unit testing to drive design when you need deterministic, traceable quality gates and living specifications. Writing tests first enforces the RED-GREEN-REFACTOR discipline to maintain regression protection.