What is the globals option?

With globals set to true you can use describe, it, expect, and vi without importing them, matching Jest behaviour. If you leave it off you must import from vitest in each file, which some teams prefer for explicitness.

v8 or istanbul for coverage?

v8 uses the engine's native coverage and is faster with no instrumentation step, which suits most projects. istanbul instruments the code and can be more precise for branch coverage but is slower. Install the matching @vitest/coverage package.

When do I need jsdom?

Choose jsdom or happy-dom whenever a test touches the DOM, such as React or Vue component tests using document, window, or testing-library. Pure logic and Node code should stay on node for speed.

What goes in the setup file?

Code that runs before each test file: importing jest-dom matchers, registering global mocks, or resetting state. List it in setupFiles so Vitest loads it automatically.

Can I merge this with vite.config.ts?

Yes. You can add the test key directly to vite.config.ts, but a separate vitest.config.ts keeps test settings isolated. When both exist, vitest.config.ts takes precedence for test runs.

vitest.config.ts Builder

Vitest configuration without the boilerplate

Vitest shares Vite’s transform pipeline, so its config is a defineConfig call with a test block. This tool assembles that block: the environment, coverage, matching patterns, setup files, and timeout, then emits a complete vitest.config.ts.

How it works

The environment value selects the global runtime each test file receives. node is a plain Node environment with no DOM, while jsdom and happy-dom install a simulated browser so document and window exist for component tests. globals: true injects describe, it, expect, and vi as globals so you do not import them, mirroring Jest.

include and exclude are glob arrays that decide which files Vitest treats as tests and which directories it skips. setupFiles lists modules run before every test file, the natural home for testing-library matchers or shared mocks. Coverage is delegated to a provider: v8 reads the engine’s built-in coverage with no instrumentation, while istanbul instruments the source for more detailed branch data. The reporters array controls output — text for the console, lcov for CI tools, and html for a browsable report under reportsDirectory.

Tips and example

Install the coverage package that matches your provider, for example @vitest/coverage-v8, or the run fails on first use. A typical DOM-test config:

import { defineConfig } from "vitest/config";

export default defineConfig({
  test: {
    globals: true,
    environment: "jsdom",
    include: ["src/**/*.{test,spec}.{ts,tsx}"],
    setupFiles: ["./test/setup.ts"],
    coverage: { provider: "v8", reporter: ["text", "lcov"] },
  },
});

Keep node as the environment for backend packages — jsdom adds noticeable startup cost you do not need when no test touches the DOM.

vitest.config.ts Builder

Email me this result

Vitest configuration without the boilerplate

How it works

Tips and example