1---
2name: vitest
3description: 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.
4metadata:
5  author: Anthony Fu
6  version: "2026.1.28"
7  source: Generated from https://github.com/vitest-dev/vitest, scripts located at https://github.com/antfu/skills
8---
9 
10Vitest 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.
11 
12**Key Features:**
13- Vite-native: Uses Vite's transformation pipeline for fast HMR-like test updates
14- Jest-compatible: Drop-in replacement for most Jest test suites
15- Smart watch mode: Only reruns affected tests based on module graph
16- Native ESM, TypeScript, JSX support without configuration
17- Multi-threaded workers for parallel test execution
18- Built-in coverage via V8 or Istanbul
19- Snapshot testing, mocking, and spy utilities
20 
21> The skill is based on Vitest 3.x, generated at 2026-01-28.
22 
23## Core
24 
25| Topic | Description | Reference |
26|-------|-------------|-----------|
27| Configuration | Vitest and Vite config integration, defineConfig usage | [core-config](references/core-config.md) |
28| CLI | Command line interface, commands and options | [core-cli](references/core-cli.md) |
29| Test API | test/it function, modifiers like skip, only, concurrent | [core-test-api](references/core-test-api.md) |
30| Describe API | describe/suite for grouping tests and nested suites | [core-describe](references/core-describe.md) |
31| Expect API | Assertions with toBe, toEqual, matchers and asymmetric matchers | [core-expect](references/core-expect.md) |
32| Hooks | beforeEach, afterEach, beforeAll, afterAll, aroundEach | [core-hooks](references/core-hooks.md) |
33 
34## Features
35 
36| Topic | Description | Reference |
37|-------|-------------|-----------|
38| Mocking | Mock functions, modules, timers, dates with vi utilities | [features-mocking](references/features-mocking.md) |
39| Snapshots | Snapshot testing with toMatchSnapshot and inline snapshots | [features-snapshots](references/features-snapshots.md) |
40| Coverage | Code coverage with V8 or Istanbul providers | [features-coverage](references/features-coverage.md) |
41| Test Context | Test fixtures, context.expect, test.extend for custom fixtures | [features-context](references/features-context.md) |
42| Concurrency | Concurrent tests, parallel execution, sharding | [features-concurrency](references/features-concurrency.md) |
43| Filtering | Filter tests by name, file patterns, tags | [features-filtering](references/features-filtering.md) |
44 
45## Advanced
46 
47| Topic | Description | Reference |
48|-------|-------------|-----------|
49| Vi Utilities | vi helper: mock, spyOn, fake timers, hoisted, waitFor | [advanced-vi](references/advanced-vi.md) |
50| Environments | Test environments: node, jsdom, happy-dom, custom | [advanced-environments](references/advanced-environments.md) |
51| Type Testing | Type-level testing with expectTypeOf and assertType | [advanced-type-testing](references/advanced-type-testing.md) |
52| Projects | Multi-project workspaces, different configs per project | [advanced-projects](references/advanced-projects.md) |
53