What testing framework does this skill support?

This skill is specifically optimized for Jest, providing domain-specific guidance on Jest matchers, mocking functions, and timer utilities.

Can this skill help with TypeScript projects?

Yes, it fully supports TypeScript, offering implementation patterns for constructor injection, type-safe mocks, and interface-based testing.

How should I name my tests when using this skill?

The skill promotes the USE pattern: [U]nit, [S]cenario, [E]xpectation (e.g., 'sum, with two valid numbers, returns their sum').

How does it handle external dependencies like APIs or databases?

It provides techniques to break dependencies using stubs and mocks, ensuring your unit tests remain fast, isolated, and run entirely in-memory.

Does it follow a specific testing philosophy?

Yes, it is based on the principles from 'The Art of Unit Testing' by Roy Osherove, which emphasizes readability, maintainability, and trust in the test suite.

JavaScript Unit Testing Expert

Name: JavaScript Unit Testing Expert
Author: el-feo

byel-feo

Security & Testing

Generates maintainable, reliable JavaScript and TypeScript unit tests using Jest and industry-standard patterns.

About

This skill equips Claude with advanced expertise in unit testing for JavaScript and TypeScript, specifically leveraging the Jest framework and the principles from 'The Art of Unit Testing' (3rd Edition). It guides developers through the entire testing lifecycle—from structuring tests with the AAA pattern and USE naming convention to handling complex scenarios like breaking external dependencies with mocks and stubs. By focusing on readability, speed, and isolation, it helps teams eliminate flaky tests and build a high-trust test suite that scales with their production codebase.

Key Features

Implements the Arrange-Act-Assert (AAA) pattern for consistent test structure
Applies USE (Unit, Scenario, Expectation) naming conventions for readable test results
Provides strategies for breaking dependencies via stubs, mocks, and dependency injection
Offers specialized patterns for testing asynchronous code, promises, and timers
Identifies and refactors common test anti-patterns and code smells
0 GitHub stars

Use Cases

Refactoring existing test suites to improve maintainability and reduce flakiness
Implementing Test-Driven Development (TDD) for new JavaScript or TypeScript features
Debugging complex test failures and improving error clarity through better assertions

About

Key Features

Implements the Arrange-Act-Assert (AAA) pattern for consistent test structure
Applies USE (Unit, Scenario, Expectation) naming conventions for readable test results
Provides strategies for breaking dependencies via stubs, mocks, and dependency injection
Offers specialized patterns for testing asynchronous code, promises, and timers
Identifies and refactors common test anti-patterns and code smells
0 GitHub stars

Use Cases

Refactoring existing test suites to improve maintainability and reduce flakiness
Implementing Test-Driven Development (TDD) for new JavaScript or TypeScript features
Debugging complex test failures and improving error clarity through better assertions