make it possible to add fetch init options

.changeset/quiet-olives-fry.md

@@ -2,7 +2,27 @@
 "wrangler": patch
 ---
 
-feat: implement fetch, and write our first integration test
+feat: implement fetch for wrangler's unstable_dev API, and write our first integration test.
+
+Prior to this PR, users of `unstable_dev` had to provide their own fetcher, and guess the address and port that the wrangler dev server was using.
+
+With this implementation, it's now possible to test wrangler, using just wrangler (and a test framework):
+
+```js
+describe("worker", async () => {
+  const worker = await wrangler.unstable_dev("src/index.ts");
+
+  const resp = await worker.fetch();
+
+  expect(resp).not.toBe(undefined);
+  if (resp) {
+    const text = await resp.text();
+    expect(text).toMatchInlineSnapshot(`"Hello World!"`);
+  }
+
+  worker.stop();
+}
+```
 
 Closes #1383
 Closes #1384

fixtures/local-mode-tests/tests/unstableDev.test.ts

@@ -1,7 +1,10 @@
 import wrangler from "wrangler";
 
 describe("worker", () => {
-	let worker: { fetch: () => Promise<Response | undefined>; stop: () => void };
+	let worker: {
+		fetch: (init?: RequestInit) => Promise<Response | undefined>;
+		stop: () => void;
+	};
 
 	beforeAll(async () => {
 		//since the script is invoked from the directory above, need to specify index.js is in src/

packages/wrangler/src/api/dev.ts

@@ -1,7 +1,7 @@
 import { startDev } from "../dev";
 import { logger } from "../logger";
 
-import type { Response } from "undici";
+import type { RequestInit, Response } from "undici";
 
 interface DevOptions {
 	env?: string;
@@ -29,7 +29,7 @@ export async function unstable_dev(script: string, options: DevOptions) {
 
 	return new Promise<{
 		stop: () => void;
-		fetch: () => Promise<Response | undefined>;
+		fetch: (init?: RequestInit) => Promise<Response | undefined>;
 	}>((resolve) => {
 		//lmao
 		return new Promise<Awaited<ReturnType<typeof startDev>>>((ready) => {

packages/wrangler/src/dev.tsx

@@ -24,6 +24,7 @@ import {
 
 import type { Config } from "./config";
 import type { Route } from "./config/environment";
+import type { RequestInit } from "undici";
 import type { Argv, ArgumentsCamelCase } from "yargs";
 
 interface DevArgs {
@@ -509,11 +510,11 @@ export async function startDev(args: ArgumentsCamelCase<DevArgs>) {
 				devReactElement.unmount();
 				await watcher?.close();
 			},
-			fetch: async () => {
+			fetch: async (init?: RequestInit) => {
 				const port = args.port || config.dev.port || (await getLocalPort());
 				const address = args.ip || config.dev.ip || "localhost";
 
-				return await fetch(`http://${address}:${port}/`);
+				return await fetch(`http://${address}:${port}/`, init);
 			},
 		};
 	} finally {

packages/wrangler/src/dev/local.tsx

@@ -255,7 +255,7 @@ function useLocalWorker({
 			});
 			//TODO: instead of being lucky with spawn's timing, have miniflare-cli notify wrangler that it's ready in packages/wrangler/src/miniflare-cli/index.ts, after the mf.startScheduler promise resolves
 			if (onReady) {
-				await new Promise((resolve) => setTimeout(resolve, 400));
+				await new Promise((resolve) => setTimeout(resolve, 500));
 				onReady();
 			}