vitest

Vite-native JavaScript testing framework

TLDR

Run tests in watch mode (default in development)

$ vitest

Run tests once and exit

$ vitest run

Run tests with coverage

$ vitest --coverage

Run specific test files

$ vitest [path/to/test.spec.ts]

Run tests matching a pattern

$ vitest -t "[pattern]"

Run tests in a specific directory

$ vitest [path/to/tests]

Run in UI mode (browser-based interface)

$ vitest --ui

Update snapshots

$ vitest -u

SYNOPSIS

vitest [run|watch|bench] [options] [filters...]

Vitest is a next-generation JavaScript/TypeScript testing framework powered by Vite. It provides fast test execution through native ES module support, intelligent watch mode similar to HMR, and a Jest-compatible API for easy migration.
The framework shares Vite's configuration, transformers, resolvers, and plugins, allowing tests to use the same setup as the application. It supports DOM mocking via JSDOM or happy-dom, component testing for Vue, React, Svelte, and other frameworks, and browser-based testing.
Vitest automatically enters watch mode in development environments and run mode in CI. Configuration can be placed in vitest.config.ts or within the existing vite.config.ts under the test property. Built-in features include snapshot testing, mocking with Tinyspy, and code coverage via v8 or istanbul.

PARAMETERS

run

Run tests once without watch mode.

watch

Run tests in watch mode, re-running on file changes.

bench

Run benchmark tests.

--coverage

Enable code coverage reporting (v8 or istanbul).

-t, --testNamePattern pattern

Run only tests with names matching the pattern.

--ui

Open the Vitest UI in a browser for interactive test viewing.

-u, --update

Update snapshot files.

--reporter name

Specify reporter: default, verbose, dot, json, junit.

--config file

Path to config file.

--root dir

Root directory for the project.

--environment env

Test environment: node, jsdom, happy-dom.

--threads

Enable multi-threading (default: true).

--browser

Run tests in browser mode.

--passWithNoTests

Exit successfully even if no tests are found.

--bail n

Stop after n test failures.

CAVEATS

Requires Node.js 18 or higher. Watch mode may have high CPU usage on large projects; configure ignore patterns appropriately. Some Jest features have slightly different implementations. Browser mode requires additional setup.

HISTORY

Vitest was created by Anthony Fu and the Vite team, with the first stable release in December 2022. It was designed to address the need for a testing framework that natively integrates with Vite's development server and build pipeline. The project rapidly gained adoption as the recommended testing solution for Vite-based applications.