vitest

by @antfu in AI & LLM

868

# Install this skill:

npx skills add antfu/skills --skill "vitest"

Install specific skill from multi-skill repository

# Description

Vitest fast unit testing framework powered by Vite with Jest-compatible API. Use when writing tests, mocking, configuring coverage, or working with test filtering and fixtures.

# SKILL.md

name: vitest
description: Vitest fast unit testing framework powered by Vite with Jest-compatible API. Use when writing tests, mocking, configuring coverage, or working with test filtering and fixtures.
metadata:
author: Anthony Fu
version: "2026.1.28"
source: Generated from https://github.com/vitest-dev/vitest, scripts located at https://github.com/antfu/skills

Vitest is a next-generation testing framework powered by Vite. It provides a Jest-compatible API with native ESM, TypeScript, and JSX support out of the box. Vitest shares the same config, transformers, resolvers, and plugins with your Vite app.

Key Features:
- Vite-native: Uses Vite's transformation pipeline for fast HMR-like test updates
- Jest-compatible: Drop-in replacement for most Jest test suites
- Smart watch mode: Only reruns affected tests based on module graph
- Native ESM, TypeScript, JSX support without configuration
- Multi-threaded workers for parallel test execution
- Built-in coverage via V8 or Istanbul
- Snapshot testing, mocking, and spy utilities

The skill is based on Vitest 3.x, generated at 2026-01-28.

Core

Topic	Description	Reference
Configuration	Vitest and Vite config integration, defineConfig usage	core-config
CLI	Command line interface, commands and options	core-cli
Test API	test/it function, modifiers like skip, only, concurrent	core-test-api
Describe API	describe/suite for grouping tests and nested suites	core-describe
Expect API	Assertions with toBe, toEqual, matchers and asymmetric matchers	core-expect
Hooks	beforeEach, afterEach, beforeAll, afterAll, aroundEach	core-hooks

Features

Topic	Description	Reference
Mocking	Mock functions, modules, timers, dates with vi utilities	features-mocking
Snapshots	Snapshot testing with toMatchSnapshot and inline snapshots	features-snapshots
Coverage	Code coverage with V8 or Istanbul providers	features-coverage
Test Context	Test fixtures, context.expect, test.extend for custom fixtures	features-context
Concurrency	Concurrent tests, parallel execution, sharding	features-concurrency
Filtering	Filter tests by name, file patterns, tags	features-filtering

Advanced

Topic	Description	Reference
Vi Utilities	vi helper: mock, spyOn, fake timers, hoisted, waitFor	advanced-vi
Environments	Test environments: node, jsdom, happy-dom, custom	advanced-environments
Type Testing	Type-level testing with expectTypeOf and assertType	advanced-type-testing
Projects	Multi-project workspaces, different configs per project	advanced-projects

# Supported AI Coding Agents

This skill is compatible with the SKILL.md standard and works with all major AI coding agents:

⚡ Amp 🚀 Antigravity 🤖 Claude Code 🦀 Clawdbot 📝 Codex ▶️ Cursor 🤖 Droid 💎 Gemini CLI 🐙 GitHub Copilot 🪿 Goose 📊 Kilo Code 🔧 Kiro CLI 💻 OpenCode 🦘 Roo Code 🌲 Trae 🏄 Windsurf

Learn more about the SKILL.md standard and how to use these skills with your preferred AI coding agent.