test-driven-development

Enforces red-green-refactor test-driven development workflow before writing implementation code.

Updated May 16, 2026
One-click install
npx skills add https://github.com/michalo1334/ScenarioImpactDSL --skill test-driven-development-michalo1334
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: test-driven-development
Source: https://github.com/michalo1334/ScenarioImpactDSL/tree/main/.opencode/skills/test-driven-development
Command: npx skills add https://github.com/michalo1334/ScenarioImpactDSL --skill test-driven-development-michalo1334

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Developers often write production code first and add tests afterward, which produces tests that pass immediately and prove nothing about correctness. This Skill enforces a strict test-first discipline so every feature and bugfix is backed by a test that was watched failing before implementation. ## Core Features & Use Cases - Red-Green-Refactor Enforcement: Guides the full TDD cycle with mandatory verification that each test fails for the right reason before any implementation code is written. - Rationalization Detection: Lists common excuses for skipping TDD (such as "too simple to test" or "I'll test after") and explains why each one fails, with red flags that trigger starting over. - Testing Anti-Pattern Reference: A companion reference covers testing mock behavior, test-only methods in production classes, incomplete mocks, and mocking without understanding dependencies. - Use Case: When fixing a bug where an empty email is accepted, write a failing test asserting the rejection, watch it fail, implement the minimal validation, verify it passes, then refactor. ## Quick Start Ask the AI to implement a new feature or bugfix using strict test-driven development with a failing test written and verified first.

Frequently Asked Questions about test-driven-development

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

FAQPage Schema
How do I practice test-driven development on a new feature?▼

Write one minimal failing test describing the desired behavior, run it to confirm it fails for the right reason, then write the simplest code that passes. After green, refactor while keeping tests passing, and repeat for the next behavior.

How do I write a failing test for a bug fix?▼

Write a test that reproduces the bug, such as asserting that an empty email returns an error, and run it to watch it fail. Then implement the minimal fix, verify the test passes, and confirm no other tests break.

Why should tests be written before implementation code?▼

Tests written after code pass immediately, which proves nothing about whether they test the right behavior. Watching a test fail first confirms it actually exercises the missing feature rather than existing behavior or a typo.

When is it acceptable to skip test-driven development?▼

Exceptions are limited to throwaway prototypes, generated code, and configuration files, and only with explicit approval from your human partner. Exploration is allowed, but the exploratory code must be discarded before restarting with TDD.

What are common testing anti-patterns with mocks?▼

Common anti-patterns include asserting on mock elements instead of real behavior, adding test-only methods to production classes, mocking without understanding side effects, and creating incomplete mocks missing fields downstream code uses.