Does this skill support both Jest and Vitest?

Yes, it provides standardized patterns for both frameworks, including 'jest.mock' and 'vi.mock' syntax.

How does it handle mock state between tests?

The skill includes best practices for mock lifecycle management, utilizing clearAllMocks and restoreAllMocks to ensure test isolation.

Can I use this for testing asynchronous code?

Absolutely. It covers mocking resolved/rejected promises and using fake timers to test async behavior without actual delays.

What common mistakes does this skill help avoid?

It specifically warns against anti-patterns like over-mocking internal modules, forgetting to restore timers, and leaking mock state between test cases.

Is it useful for both frontend and backend projects?

Yes, the mocking patterns are applicable to any JavaScript or TypeScript environment where Jest or Vitest is used for testing.

Advanced JS Mocking Patterns

Name: Advanced JS Mocking Patterns
Author: Agentient

byAgentient

0•

Security & Testing

Master complex testing scenarios in Jest and Vitest using advanced module mocking, spies, and temporal control techniques.

This skill provides specialized guidance and implementation patterns for JavaScript testing using Jest and Vitest. It equips Claude with the expertise to handle sophisticated mocking requirements, such as isolating external dependencies, managing mock lifecycles to prevent state leakage, and simulating time-sensitive logic with fake timers. By enforcing best practices like proper mock restoration and avoiding implementation-detail testing, this skill ensures that test suites remain clean, reliable, and maintainable across both frontend and backend projects.

Key Features

01Full and partial module mocking for Jest and Vitest frameworks

02Precise function spying and call tracking using spyOn

03Sequential and conditional mock implementations for complex logic branching

04Fake timer implementation for testing debounces, timeouts, and delays

050 GitHub stars

06Automated mock lifecycle management with clear, reset, and restore patterns

Use Cases

01Testing time-dependent features like auto-saving or rate-limiting without waiting

02Verifying that specific callbacks are triggered within complex UI components

03Isolating network requests or database modules during unit testing

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add agentient/vibekit advanced-js-mocking-patterns

For use in Claude.ai and ChatGPT

Key Features

01Full and partial module mocking for Jest and Vitest frameworks

02Precise function spying and call tracking using spyOn

03Sequential and conditional mock implementations for complex logic branching

04Fake timer implementation for testing debounces, timeouts, and delays

050 GitHub stars

06Automated mock lifecycle management with clear, reset, and restore patterns

Use Cases

01Testing time-dependent features like auto-saving or rate-limiting without waiting

02Verifying that specific callbacks are triggered within complex UI components

03Isolating network requests or database modules during unit testing

What are Skills?·How to Install

Install with 🐟 Skill.Fish

npx skillfish add agentient/vibekit advanced-js-mocking-patterns

For use in Claude.ai and ChatGPT