vitest

Enforces Given/When/Then Vitest testing patterns for React components.

Updated Mar 26, 2026

Search Tags:#vitest #unit-testing #rtl #async-testing #react-testing #testing-guidelines #user-event

Ready to run

npx skills add https://github.com/johnnystefan/test-saas-business --skill vitest-johnnystefan

💬 Prompt for ChatGPT / Claude Chat▼

Please help me install this Agent Skill.
Skill: vitest
Source: https://github.com/johnnystefan/test-saas-business/tree/main/skills/vitest
Command: npx skills add https://github.com/johnnystefan/test-saas-business --skill vitest-johnnystefan

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

Ensures Vitest unit tests stay structured, readable, and reliable so React teams avoid flaky assertions and undocumented behaviors.

Core Features & Use Cases

Given/When/Then structure enforces the AAA pattern for component, hook, and utility tests.
Query priority guidelines steer testers toward accessible selectors and reduce fragile queries.
Async and mocking best practices cover userEvent, waitFor usage, and vi spies to keep suites deterministic.
Use Case: When introducing a new admin dashboard feature that fetches data asynchronously, follow these instructions to validate user interactions, state transitions, and API mocks without targeting implementation internals.

Quick Start

Apply Vitest with React Testing Library following the Given/When/Then pattern and preferred queries when validating a new component.

Frequently Asked Questions about vitest

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

FAQPage Schema

How do I structure React unit tests with Vitest and React Testing Library?▼

Use the Given/When/Then structure to organize your Vitest and React Testing Library tests. This pattern enforces the AAA standard, keeping suites readable and reliable by separating setup, execution, and assertions for components and hooks.

What is the best way to handle async testing and user events in Vitest?▼

Handle async testing in Vitest by using userEvent for interactions and waitFor for asynchronous assertions. Applying these async and mocking best practices keeps React Testing Library suites deterministic and avoids flaky behavior.

How do I choose the right React Testing Library queries to avoid fragile tests?▼

Choose React Testing Library queries based on prioritized guidelines that favor accessible selectors. This reduces reliance on fragile DOM queries and ensures component assertions remain reliable across refactoring.

Can I use Vitest unit testing for both admin and customer React apps?▼

Yes, you can apply Vitest unit testing patterns across both admin and customer React apps. Consistent guidelines validate user interactions, state transitions, and API mocks without targeting implementation internals.

Why does my Vitest suite have flaky assertions when testing API mocks?▼

Vitest suites often have flaky assertions due to undocumented behaviors or improper async handling. Enforcing structured testing patterns with vi spies and waitFor ensures API mocks are validated deterministically without targeting internals.