Getting Started

Overview

Vitest (pronounced as "veetest") is a next generation testing 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

Learn how to install by Video

npm

npm install -D vitest

yarn

yarn add -D vitest

pnpm

pnpm add -D vitest

bun

bun add -D vitest

TIP

Vitest requires Vite >=v6.0.0 and Node >=v20.0.0

It is recommended that you install a copy of vitest in your package.json, using one of the methods listed above. However, if you would prefer to run vitest directly, you can use npx vitest (the npx tool comes with npm and Node.js).

The npx tool will execute the specified command. By default, npx will first check if the command exists in the local project's binaries. If it is not found there, npx will look in the system's $PATH and execute it if found. If the command is not found in either location, npx will install it in a temporary location prior to execution.

Writing Tests

As an example, we will write a simple test that verifies the output of a function that adds two numbers.

sum.js

export function sum(a, b) {
  return a + b
}

sum.test.js

import { expect, test } from 'vitest'
import { sum } from './sum.js'

test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3)
})

TIP

By default, tests must contain .test. or .spec. in their file name.

Next, in order to execute the test, add the following section to your package.json:

package.json

{
  "scripts": {
    "test": "vitest"
  }
}

Finally, run npm run test, yarn test or pnpm test, depending on your package manager, and Vitest will print this message:

✓ sum.test.js (1)
  ✓ adds 1 + 2 to equal 3

Test Files  1 passed (1)
     Tests  1 passed (1)
  Start at  02:15:44
  Duration  311ms

WARNING

If you are using Bun as your package manager, make sure to use bun run test command instead of bun test, otherwise Bun will run its own test runner.

Your first test is passing! Continue to Writing Tests to learn about organizing tests, reading test output, and the core testing patterns you'll use every day.

To run tests once without watching for file changes, use vitest run. You can also pass additional flags like --reporter or --coverage. For a full list of CLI options, run npx vitest --help or see the CLI guide.

Configuring Vitest

Vitest reads your vite.config.* by default, so your existing Vite plugins and configuration work out-of-the-box. You can also create a dedicated vitest.config.* for test-specific settings. See the Config Reference for details.

IDE Integrations

We also provided an official extension for Visual Studio Code to enhance your testing experience with Vitest.

Install from VS Code Marketplace

Learn more about IDE Integrations

Examples

Example	Source	Playground
basic	GitHub	Play Online
fastify	GitHub	Play Online
in-source-test	GitHub	Play Online
lit	GitHub	Play Online
vue	GitHub	Play Online
marko	GitHub	Play Online
preact	GitHub	Play Online
qwik	GitHub	Play Online
react	GitHub	Play Online
solid	GitHub	Play Online
svelte	GitHub	Play Online
profiling	GitHub	Not Available
typecheck	GitHub	Play Online
projects	GitHub	Play Online

Community

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