fix: Aggregate query readtime bug (#2331)

* fix: Aggregate query readtime bug

* improve test

Author: tom-andersen

dev/src/reference/aggregate-query.ts

@@ -335,7 +335,7 @@ export class AggregateQuery<
     if (transactionOrReadTime instanceof Uint8Array) {
       runQueryRequest.transaction = transactionOrReadTime;
     } else if (transactionOrReadTime instanceof Timestamp) {
-      runQueryRequest.readTime = transactionOrReadTime;
+      runQueryRequest.readTime = transactionOrReadTime.toProto().timestampValue;
     } else if (transactionOrReadTime) {
       runQueryRequest.newTransaction = transactionOrReadTime;
     }

dev/system-test/firestore.ts

@@ -5010,6 +5010,26 @@ describe('Aggregation queries', () => {
     return Promise.all(sets);
   }
 
+  it('can run count within a transaction with readtime', async () => {
+    const doc = col.doc();
+    const writeResult: WriteResult = await doc.create({some: 'data'});
+
+    const count = await firestore.runTransaction(t => t.get(col.count()), {
+      readOnly: true,
+      readTime: writeResult.writeTime,
+    });
+    expect(count.data().count).to.equal(1);
+
+    const countBefore = await firestore.runTransaction(
+      t => t.get(col.count()),
+      {
+        readOnly: true,
+        readTime: Timestamp.fromMillis(writeResult.writeTime.toMillis() - 1),
+      }
+    );
+    expect(countBefore.data().count).to.equal(0);
+  });
+
   it('can run count query using aggregate api', async () => {
     const testDocs = {
       a: {author: 'authorA', title: 'titleA'},