Atom.

import { afterAll, beforeAll, describe, expect, it } from 'vitest';
import { unstable_dev, type UnstableDevWorker } from 'wrangler';

describe('Worker', () => {
  let worker: UnstableDevWorker;

  beforeAll(async () => {
    worker = await unstable_dev('src/index.ts');
  });

  afterAll(async () => {
    await worker.stop();
  });

  it('should return a response', async () => {
    const resp = await worker.fetch('/');
    if (resp) {
      const text = await resp.text();
      expect(text).toMatchInlineSnapshot();
    }
  });
})

    "vitest": "0.29.8",
    "wrangler": "2.13.0"