test: use immediate for chat refresh race

ui/src/ui/app-chat.test.ts

@@ -179,23 +179,13 @@ function createDeferred<T>() {
   return { promise, resolve, reject };
 }
 
-async function raceWithMacrotask(
-  promise: Promise<unknown>,
-  delayMs: number,
-): Promise<"resolved" | "pending"> {
-  let timer: NodeJS.Timeout | undefined;
-  try {
-    return await Promise.race([
-      promise.then(() => "resolved" as const),
-      new Promise<"pending">((resolve) => {
-        timer = setTimeout(() => resolve("pending"), delayMs);
-      }),
-    ]);
-  } finally {
-    if (timer) {
-      clearTimeout(timer);
-    }
-  }
+async function raceWithMacrotask(promise: Promise<unknown>): Promise<"resolved" | "pending"> {
+  return await Promise.race([
+    promise.then(() => "resolved" as const),
+    new Promise<"pending">((resolve) => {
+      setImmediate(() => resolve("pending"));
+    }),
+  ]);
 }
 
 describe("refreshChat", () => {
@@ -213,7 +203,7 @@ describe("refreshChat", () => {
     });
 
     const refresh = refreshChat(host);
-    const outcome = await raceWithMacrotask(refresh, 0);
+    const outcome = await raceWithMacrotask(refresh);
 
     expect(outcome).toBe("resolved");
     expect(host.chatLoading).toBe(true);
@@ -255,7 +245,7 @@ describe("refreshChat", () => {
     });
 
     const refresh = refreshChat(host, { awaitHistory: true, scheduleScroll: false });
-    const pendingOutcome = await raceWithMacrotask(refresh, 0);
+    const pendingOutcome = await raceWithMacrotask(refresh);
 
     expect(pendingOutcome).toBe("pending");
     history.resolve({
@@ -565,7 +555,7 @@ describe("refreshChat", () => {
         sessionKey: "main",
       });
 
-      const outcome = await raceWithMacrotask(refreshChat(host), 20);
+      const outcome = await raceWithMacrotask(refreshChat(host));
 
       expect(outcome).toBe("resolved");
       expect(host.chatMessages).toEqual([