more work on the implementation

Author: dconeybe

Firestore/Example/Tests/Integration/API/FIRQueryTests.mm

@@ -1153,6 +1153,7 @@ - (void)testUseInWithArrayContains {
   [self checkOnlineAndOfflineQuery:[collRef queryWhereFilter:filter4] matchesResult:@[ @"doc3" ]];
 }
 
+
 - (void)testOrderByEquality {
   // TODO(orquery): Enable this test against production when possible.
   XCTSkipIf(![FSTIntegrationTestCase isRunningAgainstEmulator],
@@ -1180,7 +1181,7 @@ - (void)testOrderByEquality {
                      matchesResult:@[ @"doc6", @"doc3" ]];
 }
 
-- (void)resumingAQueryShouldUseExistenceFilterToDetectDeletes {
+- (void)testResumingAQueryShouldUseExistenceFilterToDetectDeletes {
   // Prepare the names and contents of the 100 documents to create.
   NSMutableDictionary<NSString*, NSDictionary<NSString *, id>*>* testData = [[NSMutableDictionary alloc] init];
   for (int i=0; i<100; i++) {
@@ -1193,15 +1194,53 @@ - (void)resumingAQueryShouldUseExistenceFilterToDetectDeletes {
   // Run a query to populate the local cache with the 100 documents and a resume token.
   NSArray<FIRDocumentReference*>* createdDocuments;
   {
-    FIRQuerySnapshot *querySnapshot = [self readDocumentSetForRef:collRef source:FIRFirestoreSourceDefault];
+    FIRQuerySnapshot *querySnapshot1 = [self readDocumentSetForRef:collRef source:FIRFirestoreSourceDefault];
     NSMutableArray<FIRDocumentReference*>* createdDocumentsAccumulator = [[NSMutableArray alloc] init];
-    for (FIRDocumentSnapshot* documentSnapshot in querySnapshot.documents) {
+    for (FIRDocumentSnapshot* documentSnapshot in querySnapshot1.documents) {
       [createdDocumentsAccumulator addObject:documentSnapshot.reference];
     }
     createdDocuments = [createdDocumentsAccumulator copy];
   }
 
-  (void)createdDocuments;
+  // Delete 50 of the 100 documents. Do this in a transaction, rather than
+  // [FIRDocumentReference deleteDocument], to avoid affecting the local cache.
+  NSSet<NSString*>* deletedDocumentIds;
+  {
+    NSMutableSet<NSString*>* deletedDocumentIdsAccumulator = [[NSMutableSet alloc] init];
+    deletedDocumentIds = [deletedDocumentIdsAccumulator copy];
+    XCTestExpectation *expectation = [self expectationWithDescription:@"DeleteTransaction"];
+    [collRef.firestore runTransactionWithBlock:
+        ^id _Nullable(FIRTransaction* transaction, NSError** error) {
+          for (NSUInteger i=0; i<createdDocuments.count; i+=2) {
+            FIRDocumentReference* documentToDelete = createdDocuments[i];
+            [transaction deleteDocument:documentToDelete];
+            [deletedDocumentIdsAccumulator addObject:documentToDelete.documentID];
+          }
+          return @"document deletion successful";
+        }
+      completion:
+        ^(id, NSError *){
+          [expectation fulfill];
+        }
+    ];
+    [self awaitExpectation:expectation];
+  }
+
+  // Wait for 10 seconds, during which Watch will stop tracking the query and will send an existence
+  // filter rather than "delete" events when the query is resumed.
+  [NSThread sleepForTimeInterval:10.0f];
+
+  // Resume the query and save the resulting snapshot for verification.
+  FIRQuerySnapshot *querySnapshot2 = [self readDocumentSetForRef:collRef source:FIRFirestoreSourceDefault];
+
+  // Verify that the snapshot from the resumed query contains the expected documents; that is,
+  // that it contains the 50 documents that were _not_ deleted.
+  // TODO(b/270731363): Remove the "if" condition below once the Firestore Emulator is fixed to
+  // send an existence filter. At the time of writing, the Firestore emulator fails to send an
+  // existence filter, resulting in the client including the deleted documents in the snapshot
+  // of the resumed query.
+  if (!([FSTIntegrationTestCase isRunningAgainstEmulator] && querySnapshot2.count == 100)) {
+  }
 }
 
 @end