feat: testing scheduled events with wrangler dev remote mode (#1815)

Using the new middleware (#1735), we implement a way of testing scheduled workers from a fetch using `wrangler dev` in remote mode, by passing a new command line flag `--test-scheduled`. This exposes a route `/__scheduled` which will trigger the scheduled event.

```sh
$ npx wrangler dev index.js --test-scheduled

$ curl http://localhost:8787/__scheduled
```

Closes #570

.changeset/fair-chairs-rhyme.md

@@ -0,0 +1,15 @@
+---
+"wrangler": patch
+---
+
+feat: testing scheduled events with `wrangler dev` remote mode
+
+Using the new middleware (https://github.com/cloudflare/wrangler2/pull/1735), we implement a way of testing scheduled workers from a fetch using `wrangler dev` in remote mode, by passing a new command line flag `--test-scheduled`. This exposes a route `/__scheduled` which will trigger the scheduled event.
+
+```sh
+$ npx wrangler dev index.js --test-scheduled
+
+$ curl http://localhost:8787/__scheduled
+```
+
+Closes https://github.com/cloudflare/wrangler2/issues/570

packages/wrangler/src/__tests__/dev.test.tsx

@@ -1027,7 +1027,8 @@ describe("wrangler dev", () => {
 			      --node-compat                                Enable node.js compatibility  [boolean]
 			      --persist                                    Enable persistence for local mode, using default path: .wrangler/state  [boolean]
 			      --persist-to                                 Specify directory to use for local persistence (implies --persist)  [string]
-			      --inspect                                    Enable dev tools  [deprecated] [boolean]",
+			      --inspect                                    Enable dev tools  [deprecated] [boolean]
+			      --test-scheduled                             Test scheduled events by visiting /__scheduled in browser  [boolean] [default: false]",
 			  "warn": "",
 			}
 		`);

packages/wrangler/src/__tests__/middleware.scheduled.test.ts

@@ -0,0 +1,135 @@
+import * as fs from "node:fs";
+import { unstable_dev } from "../api";
+import { runInTempDir } from "./helpers/run-in-tmp";
+
+jest.unmock("undici");
+
+describe("run scheduled events with middleware", () => {
+	describe("module workers", () => {
+		runInTempDir();
+
+		beforeEach(() => {
+			const scriptContent = `
+			export default {
+				fetch(request, env, ctx) {
+					const url = new URL(request.url);
+					if (url.pathname === "/__scheduled") {
+						return new Response("Fetch triggered at /__scheduled");
+					}
+					return new Response("Hello world!");
+				},
+				scheduled(controller, env, ctx) {
+					console.log("Doing something scheduled in modules...");
+				},
+			};
+			`;
+			fs.writeFileSync("index.js", scriptContent);
+		});
+
+		it("should not intercept when middleware is not enabled", async () => {
+			const worker = await unstable_dev(
+				"index.js",
+				{},
+				{ disableExperimentalWarning: true }
+			);
+
+			const resp = await worker.fetch("/__scheduled");
+			let text;
+			if (resp) text = await resp.text();
+			expect(text).toMatchInlineSnapshot(`"Fetch triggered at /__scheduled"`);
+			await worker.stop();
+		});
+
+		it("should intercept when middleware is enabled", async () => {
+			const worker = await unstable_dev(
+				"index.js",
+				{ testScheduled: true },
+				{ disableExperimentalWarning: true }
+			);
+
+			const resp = await worker.fetch("/__scheduled");
+			let text;
+			if (resp) text = await resp.text();
+			expect(text).toMatchInlineSnapshot(`"Ran scheduled event"`);
+			await worker.stop();
+		});
+
+		it("should not trigger scheduled event on wrong route", async () => {
+			const worker = await unstable_dev(
+				"index.js",
+				{ testScheduled: true },
+				{ disableExperimentalWarning: true }
+			);
+
+			const resp = await worker.fetch("/test");
+			let text;
+			if (resp) text = await resp.text();
+			expect(text).toMatchInlineSnapshot(`"Hello world!"`);
+			await worker.stop();
+		});
+	});
+
+	describe("service workers", () => {
+		runInTempDir();
+
+		beforeEach(() => {
+			const scriptContent = `
+			addEventListener("scheduled", (event) => {
+				console.log("Doing something scheduled in service worker...");
+			});
+
+			addEventListener("fetch", (event) => {
+				const url = new URL(event.request.url);
+				if (url.pathname === "/__scheduled") {
+					event.respondWith(new Response("Fetch triggered at /__scheduled"));
+				} else {
+					event.respondWith(new Response("Hello world!"));
+				}
+			});
+			`;
+			fs.writeFileSync("index.js", scriptContent);
+		});
+
+		it("should not intercept when middleware is not enabled", async () => {
+			const worker = await unstable_dev(
+				"index.js",
+				{},
+				{ disableExperimentalWarning: true }
+			);
+
+			const resp = await worker.fetch("/__scheduled");
+			let text;
+			if (resp) text = await resp.text();
+			expect(text).toMatchInlineSnapshot(`"Fetch triggered at /__scheduled"`);
+			await worker.stop();
+		});
+
+		it("should intercept when middleware is enabled", async () => {
+			const worker = await unstable_dev(
+				"index.js",
+				{ testScheduled: true },
+				{ disableExperimentalWarning: true }
+			);
+
+			const resp = await worker.fetch("/__scheduled");
+			let text;
+			if (resp) text = await resp.text();
+			expect(text).toMatchInlineSnapshot(`"Ran scheduled event"`);
+			await worker.stop();
+		});
+
+		it("should not trigger scheduled event on wrong route", async () => {
+			const worker = await unstable_dev(
+				"index.js",
+				{ testScheduled: true },
+				{ disableExperimentalWarning: true }
+			);
+
+			const resp = await worker.fetch("/test");
+			let text;
+			if (resp) text = await resp.text();
+			expect(text).toMatchInlineSnapshot(`"Hello world!"`);
+			await worker.stop();
+		});
+	});
+});