Getting Started #

Overview #

Vitest is a blazing fast unit test framework powered by Vite.

You can learn more about the rationale behind the project in the Why Vitest section.

Trying Vitest Online #

You can try Vitest online on StackBlitz. It runs Vitest directly in the browser, and it is almost identical to the local setup but doesn't require installing anything on your machine.

Adding Vitest to your Project #

// with npm
$ npm install -D vitest

// or with yarn
$ yarn add -D vitest

// or with pnpm
$ pnpm add -D vitest

Configuring Vitest #

One of the main advantages of Vitest is its unified configuration with Vite. If present, vitest will read your root vite.config.ts to match with the plugins and setup as your Vite app. For example, your Vite resolve.alias and plugins configuration will work out-of-the-box. If you want a different configuration during testing, you can:

• Create vitest.config.ts, which will have the higher priority
• Pass --config option to CLI, e.g. vitest --config ./path/to/vitest.config.ts
• Use process.env.VITEST or mode property on defineConfig (will be set to test if not overridden) to conditionally apply different configuration in vite.config.ts

To configure vitest itself, add test property in your Vite config. You'll also need to add a reference to Vitest types using a triple slash command at the top of your config file, if you are importing defineConfig from vite itself.

import { defineConfig } from 'vitest/config'

export default defineConfig({
  test: {
    // ...
  },
})

See the list of config options in the Config Reference

Command Line Interface #

In a project where Vitest is installed, you can use the vitest binary in your npm scripts, or run it directly with npx vitest. Here are the default npm scripts in a scaffolded Vitest project:

{
  "scripts": {
    "test": "vitest",
    "coverage": "vitest run --coverage"
  }
}

To run tests once without watching for file changes, use vitest run. You can specify additional CLI options like --port or --https. For a full list of CLI options, run npx vitest --help in your project.

Commands #

• vitest watch

  Run all test suites but watch for changes and rerun tests when they change. Same as calling vitest without a command. In CI environments this command will fallback to vitest run

• vitest run

  Perform a single run without watch mode.

• vitest dev

  Run vitest in development mode.

• vitest related

  Run only tests that cover a list of source files. Works with static lazy imports, but not the dynamic ones. All files should be relative to root folder.

  Useful to run with lint-staged or with your CI setup.

  vitest related /src/index.ts /src/hello-world.js
  

Options #

Examples #

Projects using Vitest #

• unocss
• unplugin-auto-import
• unplugin-vue-components
• vitesse
• vitesse-lite
• fluent-vue
• vueuse
• milkdown
• gridjs-svelte
• spring-easing
• bytemd
• faker
• million
• Vitamin
• neodrag
• svelte-multiselect
• iconify

Using Unreleased Commits #

If you can't wait for a new release to test the latest features, you will need to clone the vitest repo to your local machine and then build and link it yourself (pnpm is required):

git clone https://github.com/vitest-dev/vitest.git
cd vitest
pnpm install
cd packages/vitest
pnpm run build
pnpm link --global # you can use your preferred package manager for this step

Then go to the project where you are using Vitest and run pnpm link --global vitest (or the package manager that you used to link vitest globally).

Community #

If you have questions or need help, reach out to the community at Discord and GitHub Discussions.