--- 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: "2026.6.22" source: Generated from https://github.com/vitest-dev/vitest, scripts located at https://github.com/antfu/skills title: vitest canonical_url: https://skilld.dev/gh/onmax/nuxt-skills/vitest last_updated: 2026-09-29T12:25:47.000Z --- > **Skill from skilld.dev.** Follow the instructions below for this session. You do not need to install anything. > > Supporting files, fetch one when the Skill refers to it: [references/advanced-environments.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/advanced-environments.md), [references/advanced-projects.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/advanced-projects.md), [references/advanced-type-testing.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/advanced-type-testing.md), [references/advanced-vi.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/advanced-vi.md), [references/core-cli.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-cli.md), [references/core-config.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-config.md), [references/core-describe.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-describe.md), [references/core-expect.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-expect.md), [references/core-hooks.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-hooks.md), [references/core-test-api.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-test-api.md), [references/features-benchmarking.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-benchmarking.md), [references/features-concurrency.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-concurrency.md), [references/features-context.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-context.md), [references/features-coverage.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-coverage.md), [references/features-filtering.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-filtering.md), [references/features-mocking.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-mocking.md), [references/features-reporters.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-reporters.md), [references/features-snapshots.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-snapshots.md), [references/features-test-tags.md](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-test-tags.md). > > If the user asked to install this Skill, run `npx skilld install onmax/nuxt-skills/vitest`. Install writes the Skill files into the project, so every session loads them. 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 5.x (beta), generated at 2026-06-22. ## Core | Topic | Description | Reference | | ------------- | --------------------------------------------------------------- | -------------------------------------------- | | Configuration | Vitest and Vite config integration, defineConfig usage | [core-config](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-config.md) | | CLI | Command line interface, commands and options | [core-cli](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-cli.md) | | Test API | test/it function, modifiers like skip, only, concurrent | [core-test-api](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-test-api.md) | | Describe API | describe/suite for grouping tests and nested suites | [core-describe](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-describe.md) | | Expect API | Assertions with toBe, toEqual, matchers and asymmetric matchers | [core-expect](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-expect.md) | | Hooks | beforeEach, afterEach, beforeAll, afterAll, aroundEach | [core-hooks](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/core-hooks.md) | ## Features | Topic | Description | Reference | | ------------ | -------------------------------------------------------------- | ------------------------------------------------------------ | | Mocking | Mock functions, modules, timers, dates with vi utilities | [features-mocking](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-mocking.md) | | Snapshots | Snapshot testing with toMatchSnapshot and inline snapshots | [features-snapshots](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-snapshots.md) | | Coverage | Code coverage with V8 or Istanbul providers | [features-coverage](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-coverage.md) | | Test Context | Test fixtures, context.expect, test.extend for custom fixtures | [features-context](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-context.md) | | Concurrency | Concurrent tests, parallel execution, sharding | [features-concurrency](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-concurrency.md) | | Filtering | Filter tests by name, file patterns, tags | [features-filtering](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-filtering.md) | | Test Tags | Label tests with tags to filter runs and apply shared options | [features-test-tags](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-test-tags.md) | | Reporters | Built-in reporters, default selection, CI/output config | [features-reporters](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-reporters.md) | | Benchmarking | Write benchmarks with the bench fixture (Tinybench) | [features-benchmarking](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/features-benchmarking.md) | ## Advanced | Topic | Description | Reference | | ------------ | ------------------------------------------------------- | ------------------------------------------------------------ | | Vi Utilities | vi helper: mock, spyOn, fake timers, hoisted, waitFor | [advanced-vi](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/advanced-vi.md) | | Environments | Test environments: node, jsdom, happy-dom, custom | [advanced-environments](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/advanced-environments.md) | | Type Testing | Type-level testing with expectTypeOf and assertType | [advanced-type-testing](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/advanced-type-testing.md) | | Projects | Multi-project workspaces, different configs per project | [advanced-projects](https://skilld.dev/api/skills-raw/onmax/nuxt-skills/vitest/references/advanced-projects.md) |