fix: retry Miniflare spawn for flaky workerd on CI

workerd occasionally fails to spawn on CI runners (child_process
connect error). Added createMiniflare() helper with 3 retries.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: brainkim

test/cloudflare-build.test.js

@@ -14,6 +14,23 @@ import {copyFixtureToTemp, fileExists} from "./utils.js";
 const TIMEOUT = 10000;
 const MINIFLARE_TIMEOUT = 30000;
 
+/**
+ * Create a Miniflare instance with retry for flaky workerd spawns on CI.
+ */
+async function createMiniflare(options, retries = 3) {
+	for (let i = 0; i < retries; i++) {
+		try {
+			const mf = new Miniflare(options);
+			await mf.ready;
+			return mf;
+		} catch (err) {
+			if (i === retries - 1) throw err;
+			// Brief pause before retry
+			await new Promise((r) => setTimeout(r, 500));
+		}
+	}
+}
+
 test(
 	"cloudflare build - basic ServiceWorker",
 	async () => {
@@ -151,15 +168,13 @@ test(
 
 			// Load and run the worker in Miniflare
 			// This will fail if setTimeout is called in global scope during lifecycle
-			mf = new Miniflare({
+			mf = await createMiniflare({
 				modules: true,
 				script,
 				compatibilityDate: "2024-09-23",
 				compatibilityFlags: ["nodejs_compat"],
 			});
 
-			await mf.ready;
-
 			// Send a request to the worker
 			const response = await mf.dispatchFetch("http://localhost/");
 			expect(response.status).toBe(200);
@@ -246,7 +261,7 @@ self.addEventListener("fetch", (event) => {
 			const workerPath = join(outDir, "server", "worker.js");
 			const script = await FS.readFile(workerPath, "utf8");
 
-			mf = new Miniflare({
+			mf = await createMiniflare({
 				modules: true,
 				script,
 				compatibilityDate: "2024-09-23",
@@ -258,8 +273,6 @@ self.addEventListener("fetch", (event) => {
 				},
 			});
 
-			await mf.ready;
-
 			// Fetch the URL map from the worker
 			const response = await mf.dispatchFetch("http://localhost/");
 			expect(response.status).toBe(200);