Wrangler's unstable_startWorker()

Note

For most users, Cloudflare recommends using the Workers Vitest integration. If you have been using unstable_dev(), refer to the Migrate from unstable_dev() guide.

Warning

unstable_startWorker() is an experimental API subject to breaking changes.

If you do not want to use Vitest, consider using Wrangler's unstable_startWorker() API. This API exposes the internals of Wrangler's dev server, and allows you to customise how it runs. Compared to using Miniflare directly for testing, you can pass in a Wrangler configuration file, and it will automatically load the configuration for you.

This example uses node:test, but should apply to any testing framework:

import assert from "node:assert";
import test, { after, before, describe } from "node:test";
import { unstable_startWorker } from "wrangler";

describe("worker", () => {
  let worker;

  before(async () => {
    worker = await unstable_startWorker({ config: "wrangler.json" });
  });

  test("hello world", async () => {
    assert.strictEqual(
      await (await worker.fetch("http://example.com")).text(),
      "Hello world",
    );
  });

  after(async () => {
    await worker.dispose();
  });
});