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test-driven-development

Guides test-first development using the red-green-refactor cycle for code changes and bug fixes.

Updated May 19, 2026
Search Tags:#tdd#unit testing#mocks#regression testing#red green refactor#bug reproduction#test pyramid
One-click install
npx skills add https://github.com/LonelyTraderBay/vittrade-flutter --skill test-driven-development-lonelytraderbay
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: test-driven-development
Source: https://github.com/LonelyTraderBay/vittrade-flutter/tree/main/.agents/skills/test-driven-development
Command: npx skills add https://github.com/LonelyTraderBay/vittrade-flutter --skill test-driven-development-lonelytraderbay

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve? Code changes made without tests are unverified and fragile. This Skill enforces a test-first workflow so every new behavior, bug fix, or refactor is proven by a failing-then-passing test instead of manual spot checks. ## Core Features & Use Cases - Red-Green-Refactor Cycle: Write a failing test first, implement the minimal code to pass it, then refactor with tests staying green. - Prove-It Pattern for Bugs: Reproduce any reported bug with a failing test before attempting a fix, creating a permanent regression guard. - Test Quality Guidance: Apply the test pyramid, test size classification, DAMP-over-DRY style, state-based assertions, and a real-over-mocks preference order. - Use Case: A bug report says completing a task does not set its timestamp. Write a reproduction test that fails, implement the fix, watch the test pass, then run the full suite to confirm no regressions. ## Quick Start Ask the agent to implement the next feature or fix the reported bug using test-driven development with a failing test written 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 a failing test that describes the desired behavior first, then write the minimal code to make it pass, then refactor while keeping tests green. Repeat this red-green-refactor cycle for each increment of functionality.

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

Reproduce the bug with a test before fixing anything. Confirm the test fails, proving the bug exists, then implement the fix and confirm the test passes. This creates a permanent guard against the bug returning.

When should I use mocks versus real implementations in tests?▼

Prefer real implementations first, then fakes, stubs, and finally mocks. Reserve mocks for dependencies that are too slow, non-deterministic, or have uncontrollable side effects like external APIs or email sending.

When is test-driven development not appropriate?▼

Skip TDD for pure configuration changes, documentation updates, or static content with no behavioral impact. Any change that alters logic or behavior should be covered by a test written first.

Why do my tests break every time I refactor code?▼

Tests that assert on internal method calls or implementation details break during refactoring even when behavior is unchanged. Assert on inputs and outputs instead, testing state rather than interactions.

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