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
      },
    };
  },
};