Add expected count to Target (#10872)

Author: milaGGL

Firestore/Example/Tests/SpecTests/FSTMockDatastore.mm

@@ -115,6 +115,11 @@ void WatchQuery(const TargetData& query) override {
     // Snapshot version is ignored on the wire
     TargetData sentTargetData =
         query.WithResumeToken(query.resume_token(), SnapshotVersion::None());
+
+    if (query.expected_count().has_value()) {
+      sentTargetData = sentTargetData.WithExpectedCount(query.expected_count().value());
+    }
+
     datastore_->IncrementWatchStreamRequests();
     active_targets_[query.target_id()] = sentTargetData;
   }

Firestore/Example/Tests/SpecTests/FSTSpecTests.mm

@@ -780,6 +780,10 @@ - (void)validateExpectedState:(nullable NSDictionary *)expectedState {
                 target_data = target_data.WithResumeToken(
                     ByteString(), [self parseVersion:queryData[@"readTime"]]);
               }
+
+              if ([queryData objectForKey:@"expectedCount"] != nil) {
+                target_data = target_data.WithExpectedCount([queryData[@"expectedCount"] intValue]);
+              }
               queries.push_back(std::move(target_data));
             }
             expectedActiveTargets[targetID] = std::move(queries);
@@ -896,7 +900,13 @@ - (void)validateActiveTargets {
     XCTAssertEqual(actual.target_id(), targetData.target_id());
     XCTAssertEqual(actual.snapshot_version(), targetData.snapshot_version());
     XCTAssertEqual(actual.resume_token(), targetData.resume_token());
-
+    if (targetData.expected_count().has_value()) {
+      if (!actual.expected_count().has_value()) {
+        XCTFail("Actual target data doesn't have an expected_count.");
+      } else {
+        XCTAssertEqual(actual.expected_count().value(), targetData.expected_count().value());
+      }
+    }
     actualTargets.erase(targetID);
   }