Posted inCloudflare

Workers – Run integration tests against your Worker’s production build

3 minutesPosted inCloudflare

Wrangler now provides createTestHarness(), an API for running integration tests against Workers built with Wrangler or the Cloudflare Vite plugin from any Node.js test runner.

The test harness starts a local Worker server with helpers for dispatching requests, resetting storage, and inspecting runtime logs.

This is useful for tests that need to:

For example, this test starts two Workers and mocks an upstream API:

tests/vitest.test.jsjs
import { afterAll, afterEach, beforeAll, test } from "vitest";
import { http, HttpResponse } from "msw";
import { setupServer } from "msw/node";
import { createTestHarness } from "wrangler";

const network = setupServer();
const server = createTestHarness({
	workers: [
		/** Includes `"routes": ["example.com/*"]` */
		{ configPath: "./workers/web/wrangler.jsonc" },
		/** Includes `"routes": ["api.example.com/v1/*"]` */
		{ configPath: "./workers/api/wrangler.jsonc" },
	],
});

beforeAll(async () => {
	network.listen({ onUnhandledRequest: "error" });
	await server.listen();
});

afterEach(async () => {
	network.resetHandlers();
	await server.reset();
});

afterAll(async () => {
	network.close();
	await server.close();
});

test("routes requests to each Worker", async ({ expect }) => {
	// Mock the outbound fetch used to load user profiles.
	network.use(
		http.get("http://identity.example.com/profile/123", ({ params }) => {
			return HttpResponse.json({ id: 123, name: "Ada" });
		}),
	);

	const apiWorkerResponse = await server.fetch(
		"http://api.example.com/v1/users/123",
	);
	expect(await apiWorkerResponse.json()).toEqual({
		id: 123,
		name: "Ada",
	});

	const webWorkerResponse = await server.fetch("http://example.com/users/123");
	expect(await webWorkerResponse.text()).toBe("Profile: Ada");
});
tests/vitest.test.tsts
import { afterAll, afterEach, beforeAll, test } from "vitest";
import { http, HttpResponse } from "msw";
import { setupServer } from "msw/node";
import { createTestHarness } from "wrangler";

const network = setupServer();
const server = createTestHarness({
	workers: [
		/** Includes `"routes": ["example.com/*"]` */
		{ configPath: "./workers/web/wrangler.jsonc" },
		/** Includes `"routes": ["api.example.com/v1/*"]` */
		{ configPath: "./workers/api/wrangler.jsonc" },
	],
});

beforeAll(async () => {
	network.listen({ onUnhandledRequest: "error" });
	await server.listen();
});

afterEach(async () => {
	network.resetHandlers();
	await server.reset();
});

afterAll(async () => {
	network.close();
	await server.close();
});

test("routes requests to each Worker", async ({ expect }) => {
	// Mock the outbound fetch used to load user profiles.
	network.use(
		http.get("http://identity.example.com/profile/123", ({ params }) => {
			return HttpResponse.json({ id: 123, name: "Ada" });
		}),
	);

	const apiWorkerResponse = await server.fetch(
		"http://api.example.com/v1/users/123",
	);
	expect(await apiWorkerResponse.json()).toEqual({
		id: 123,
		name: "Ada",
	});

	const webWorkerResponse = await server.fetch("http://example.com/users/123");
	expect(await webWorkerResponse.text()).toBe("Profile: Ada");
});

Cloudflare now recommends createTestHarness() for integration tests instead of unstable_startWorker() or unstable_dev(). To start a development server programmatically, use the Vite createServer() ↗ API with the Cloudflare Vite plugin.

For more information about createTestHarness(), refer to the Integration test harness guide.

Source: Cloudflare

Share This Update