vitest
Use when writing unit/integration tests for Vite projects - configure vitest.config.ts, write test suites with describe/it, create mock implementations with vi.fn and vi.mock, set up code coverage thresholds, and run tests in parallel
Best use case
vitest is best used when you need a repeatable AI agent workflow instead of a one-off prompt.
Use when writing unit/integration tests for Vite projects - configure vitest.config.ts, write test suites with describe/it, create mock implementations with vi.fn and vi.mock, set up code coverage thresholds, and run tests in parallel
Teams using vitest should expect a more consistent output, faster repeated execution, less prompt rewriting.
When to use this skill
- You want a reusable workflow that can be run more than once with consistent structure.
When not to use this skill
- You only need a quick one-off answer and do not need a reusable workflow.
- You cannot install or maintain the underlying files, dependencies, or repository context.
Installation
Claude Code / Cursor / Codex
Manual Installation
- Download SKILL.md from GitHub
- Place it in
.claude/skills/vitest/SKILL.mdinside your project - Restart your AI agent — it will auto-discover the skill
How vitest Compares
| Feature / Agent | vitest | Standard Approach |
|---|---|---|
| Platform Support | Not specified | Limited / Varies |
| Context Awareness | High | Baseline |
| Installation Complexity | Unknown | N/A |
Frequently Asked Questions
What does this skill do?
Use when writing unit/integration tests for Vite projects - configure vitest.config.ts, write test suites with describe/it, create mock implementations with vi.fn and vi.mock, set up code coverage thresholds, and run tests in parallel
Where can I find the source code?
You can find the source code on GitHub using the link provided at the top of the page.
Related Guides
SKILL.md Source
# Vitest
Vite-native testing framework with Jest-compatible API.
## When to Use
- Writing unit/integration tests for Vite projects
- Testing Vue/React/Svelte components
- Mocking modules, timers, or dates
- Running concurrent/parallel tests
- Type testing with TypeScript
## Quick Start
```bash
npm i -D vitest
```
```ts
// vitest.config.ts
import { defineConfig } from 'vitest/config'
export default defineConfig({
test: {
globals: true,
environment: 'node', // or 'jsdom' for DOM tests
},
})
```
```ts
// example.test.ts
import { describe, expect, it, vi } from 'vitest'
describe('math', () => {
it('adds numbers', () => {
expect(1 + 1).toBe(2)
})
})
```
## Reference Files
| Task | File |
| ---------------------------------------- | --------------------------------------- |
| Configuration, CLI, projects | [config.md](references/config.md) |
| test/describe, hooks, fixtures | [test-api.md](references/test-api.md) |
| vi.fn, vi.mock, timers, spies | [mocking.md](references/mocking.md) |
| expect, snapshots, coverage, filtering | [utilities.md](references/utilities.md) |
| Environments, type testing, browser mode | [advanced.md](references/advanced.md) |
## Loading Files
**Consider loading these reference files based on your task:**
- [ ] [references/config.md](references/config.md) - if setting up vitest.config.ts, CLI, or workspace projects
- [ ] [references/test-api.md](references/test-api.md) - if writing test/describe blocks, using hooks, or test fixtures
- [ ] [references/mocking.md](references/mocking.md) - if mocking modules, timers, dates, or using spies
- [ ] [references/utilities.md](references/utilities.md) - if writing assertions, snapshots, or configuring coverage
- [ ] [references/advanced.md](references/advanced.md) - if configuring test environments, type testing, or browser mode
**DO NOT load all files at once.** Load only what's relevant to your current task.
## Cross-Skill References
- **Vue component testing** → Use `vue` skill for component patterns
- **Library testing** → Use `ts-library` skill for library patterns
- **Vite configuration** → Use `vite` skill for shared configRelated Skills
writing-web-documentation
Write, rewrite, review, and organize developer-facing documentation for web software projects. Use when creating or improving README files, docs homepages, quickstarts, tutorials, how-to guides, API/reference pages, conceptual explanations, migration guides, or troubleshooting content for frontend, backend, full-stack, SDK, API, or framework-based web products. This skill applies strong information architecture, task-first page structure, clear voice, runnable examples, version and prerequisite hygiene, accessibility rules, and docs-as-code maintenance habits. Do not use it for marketing copy, legal text, or non-technical customer-support articles.
vueuse
Use when working with VueUse composables - track mouse position with useMouse, manage localStorage with useStorage, detect network status with useNetwork, debounce values with refDebounced, and access browser APIs reactively. Check VueUse before writing custom composables - most patterns already implemented.
vue
Use when editing .vue files, creating Vue 3 components, writing composables, or testing Vue code - provides Composition API patterns, props/emits best practices, VueUse integration, and reactive destructuring guidance
vite
Vite build tool configuration, plugin API, SSR, and Vite 8 Rolldown migration. Use when working with Vite projects, vite.config.ts, Vite plugins, or building libraries/SSR apps with Vite.
tsdown
Use when bundling TypeScript libraries - provides tsdown configuration, dual ESM/CJS output, .d.ts generation, package validation, and plugin authoring
ts-library
Use when authoring TypeScript libraries or npm packages - covers project setup, package.json exports, build tooling (tsdown/unbuild), API design patterns, type inference tricks, testing, and publishing to npm. Use when bundling, configuring dual CJS/ESM output, or setting up release workflows.
tresjs
Use when building 3D scenes with TresJS (Vue Three.js) - provides TresCanvas, composables (useTres, useLoop), Cientos helpers (OrbitControls, useGLTF, Environment), and post-processing effects
reka-ui
Use when building with Reka UI (headless Vue components) - provides component API, accessibility patterns, composition (asChild), controlled/uncontrolled state, virtualization, and styling integration. Formerly Radix Vue.
pnpm
Use when managing Node.js dependencies with pnpm - install packages, configure monorepo workspaces, set up pnpm catalogs, resolve dependency conflicts with overrides, patch third-party packages, and configure CI pipelines for pnpm projects
phaser-best-practices
Builds and refactors Phaser 3 browser games. Use for creating a new Phaser project, adding scenes, entities, physics, UI, tilemaps, animations, input, audio, camera, or for fixing Phaser-specific bugs and performance problems.
nuxthub
Use when building NuxtHub v0.10.6 applications - provides database (Drizzle ORM with sqlite/postgresql/mysql), KV storage, blob storage, and cache APIs. Covers configuration, schema definition, migrations, multi-cloud deployment (Cloudflare, Vercel), and the new hub:db, hub:kv, hub:blob virtual module imports.
nuxt
Use when working on Nuxt 4+ projects - provides server routes, file-based routing, middleware patterns, Nuxt-specific composables, and configuration with latest docs. Covers h3 v1 helpers (validation, WebSocket, SSE) and nitropack v2 patterns. Updated for Nuxt 4.3+.