fix: replace polling with direct read in data-emulator log tests

The log increment tests used waitForLog() which polled Firestore in a
loop for up to 30s. Under CI load with parallel test files, the
combined time for two requests + two polling cycles often exceeded the
30s jest timeout, causing flaky failures.

Since writeLog() is awaited inside apiData before the response is sent,
the log document is guaranteed to exist by the time saveData() returns.
Replace the polling with a simple direct read after a small delay,
and remove the now-unused waitForLog helper.

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

Author: jodeleeuw

functions/src/__tests__/data-emulator.test.js

@@ -30,17 +30,6 @@ const config = {
 
 jest.setTimeout(30000);
 
-async function waitForLog(db, docId, field, expectedValue, timeoutMs = 30000) {
-  const start = Date.now();
-  while (Date.now() - start < timeoutMs) {
-    const doc = await db.collection("logs").doc(docId).get();
-    if (doc.exists && doc.data()?.[field] === expectedValue) {
-      return doc;
-    }
-    await new Promise((resolve) => setTimeout(resolve, 250));
-  }
-  return db.collection("logs").doc(docId).get();
-}
 
 beforeAll(async () => {
   initializeApp(config);
@@ -78,20 +67,26 @@ describe("apiData", () => {
   it("should increment the write request log for the experiment when there is a complete request", async () => {
     const db = getFirestore();
     await db.collection("logs").doc("testlog").delete();
+    // writeLog is awaited inside apiData before the response is sent,
+    // so the log document should exist by the time we get the response.
     await saveData({
       experimentID: "testlog",
       data: "test",
       filename: "test",
     });
-    let doc = await waitForLog(db, "testlog", "saveData", 1);
+    // Small delay to allow Firestore emulator to sync
+    await new Promise((resolve) => setTimeout(resolve, 500));
+    let doc = await db.collection("logs").doc("testlog").get();
+    expect(doc.exists).toBe(true);
     expect(doc.data().saveData).toBe(1);
 
     await saveData({
       experimentID: "testlog",
       data: "test",
       filename: "test",
     });
-    doc = await waitForLog(db, "testlog", "saveData", 2);
+    await new Promise((resolve) => setTimeout(resolve, 500));
+    doc = await db.collection("logs").doc("testlog").get();
     expect(doc.data().saveData).toBe(2);
   });
 
@@ -106,7 +101,9 @@ describe("apiData", () => {
       filename: "test",
     });
 
-    let doc = await waitForLog(db, "data-testexp", "logError", 1);
+    await new Promise((resolve) => setTimeout(resolve, 500));
+    let doc = await db.collection("logs").doc("data-testexp").get();
+    expect(doc.exists).toBe(true);
     expect(doc.data().logError).toBe(1);
 
     await db.collection("experiments").doc("data-testexp").set(
@@ -124,7 +121,8 @@ describe("apiData", () => {
       filename: "test",
     });
 
-    doc = await waitForLog(db, "data-testexp", "logError", 2);
+    await new Promise((resolve) => setTimeout(resolve, 500));
+    doc = await db.collection("logs").doc("data-testexp").get();
     expect(doc.data().logError).toBe(2);
 
   });