Specific Files

vitest.config.ts

// @vitest-environment jsdom
import { expect, test } from 'vitest'

test('test', () => {
  expect(typeof window).not.toBe('undefined')
})

Custom Environment

vitest.config.ts

import type { Environment } from 'vitest'

export default <Environment>{
  name: 'custom',
  transformMode: 'ssr',
  // optional - only if you support "experimental-vm" pool
  async setupVM() {
    const vm = await import('node:vm')
    const context = vm.createContext()
    return {
      getVmContext() {
        return context
      },
      teardown() {
        // called after all tests with this env have been run
      }
    }
  },
  setup() {
    // custom setup
    return {
      teardown() {
        // called after all tests with this env have been run
      }
    }
  }
}