Why does it recommend a flat structure?

A flat structure avoids overly deep nesting in describe blocks, making tests easier to scan, read, and maintain as the project grows.

When should I use mocks according to these rules?

Mocks are restricted to external dependencies like HTTP requests, database connections, file system access, and time-dependent logic to ensure tests verify actual code behavior.

What is the recommended ratio for the testing pyramid?

The skill suggests a distribution of 70-80% unit tests, 15-25% integration tests, and 5-10% E2E tests for optimal stability and speed.

Which testing frameworks are supported?

This skill is specifically designed for projects using Vitest or Jest.

TypeScript Unit Testing Rules

Name: TypeScript Unit Testing Rules
Author: DIO0550

byDIO0550

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Security & Testing

Enforces standardized unit testing practices and architectural patterns for TypeScript projects using Vitest or Jest.

This skill provides a comprehensive framework for writing high-quality unit tests in TypeScript. It guides Claude to implement a flat test structure, minimize the use of mocks to favor real-world behavior, and utilize parameterized testing with test.each for better coverage. By adhering to the testing pyramid principles and emphasizing behavior over implementation details, it ensures that test suites remain maintainable, readable, and effective at catching bugs across normal, error, and boundary cases.

Key Features

011 GitHub stars

02Enforces a flat test structure to improve readability and reduce nesting

03Promotes behavior-driven testing over implementation detail verification

04Defines a clear testing pyramid to balance unit, integration, and E2E tests

05Implements strict guidelines for minimal mocking of internal logic

06Standardizes the use of parameterized tests for comprehensive edge case coverage

Use Cases

01Standardizing test suites across a large TypeScript codebase or team

02Migrating from heavy mocking to more resilient, behavior-based unit tests

03Refactoring messy, deeply nested test files into a maintainable flat structure

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add dio0550/d-market testing

For use in Claude.ai and ChatGPT

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