Do not continue with fetch if we do not get a valid IID. (#4745)

* Do not continue with fetch if we do not get a valid IID.

* Address review changes to test file.

* Update test file based on review comments.

* Fix warnings.

* Fix build.

* Fix build.

Author: dmandar

FirebaseRemoteConfig/Sources/RCNFetch.m

@@ -197,58 +197,76 @@ - (void)fetchConfigWithExpirationDuration:(NSTimeInterval)expirationDuration
 
 #pragma mark - Fetch helpers
 
-/// Refresh instance ID token before fetching config. Instance ID is an optional field in config
-/// request.
+/// Refresh instance ID token before fetching config. Instance ID is now mandatory for fetch
+/// requests to work.(b/14751422).
 - (void)refreshInstanceIDTokenAndFetchCheckInInfoWithCompletionHandler:
     (FIRRemoteConfigFetchCompletion)completionHandler {
   FIRInstanceID *instanceID = [FIRInstanceID instanceID];
-  // Only refresh instance ID when a valid sender ID is provided. If not, continue without
-  // fetching instance ID. Instance ID is for data analytics purpose, which is only optional for
-  // config fetching.
   if (!_options.GCMSenderID) {
-    [self fetchCheckinInfoWithCompletionHandler:completionHandler];
-    return;
+    NSString *errorDescription = @"Failed to get GCMSenderID";
+    FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000074", @"%@",
+                [NSString stringWithFormat:@"%@", errorDescription]);
+    return [self
+        reportCompletionOnHandler:completionHandler
+                       withStatus:FIRRemoteConfigFetchStatusFailure
+                        withError:[NSError errorWithDomain:FIRRemoteConfigErrorDomain
+                                                      code:FIRRemoteConfigErrorInternalError
+                                                  userInfo:@{
+                                                    NSLocalizedDescriptionKey : errorDescription
+                                                  }]];
   }
   FIRInstanceIDTokenHandler instanceIDHandler = ^(NSString *token, NSError *error) {
-    if (error) {
-      FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000020",
-                  @"Failed to register InstanceID with error : %@.", error);
+    if (!token || error) {
+      NSString *errorDescription =
+          [NSString stringWithFormat:@"Failed to get InstanceID token. Error : %@.", error];
+      FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000073", @"%@",
+                  [NSString stringWithFormat:@"%@", errorDescription]);
+      return [self
+          reportCompletionOnHandler:completionHandler
+                         withStatus:FIRRemoteConfigFetchStatusFailure
+                          withError:[NSError errorWithDomain:FIRRemoteConfigErrorDomain
+                                                        code:FIRRemoteConfigErrorInternalError
+                                                    userInfo:@{
+                                                      NSLocalizedDescriptionKey : errorDescription
+                                                    }]];
     }
 
     // If the token is available, try to get the instanceID.
     __weak RCNConfigFetch *weakSelf = self;
-    if (token) {
-      [instanceID getIDWithHandler:^(NSString *_Nullable identity, NSError *_Nullable error) {
-        RCNConfigFetch *strongSelf = weakSelf;
-
-        // Dispatch to the RC serial queue to update settings on the queue.
-        dispatch_async(strongSelf->_lockQueue, ^{
-          RCNConfigFetch *strongSelfQueue = weakSelf;
+    [instanceID getIDWithHandler:^(NSString *_Nullable identity, NSError *_Nullable error) {
+      RCNConfigFetch *strongSelf = weakSelf;
 
-          // Update config settings with the IID and token.
-          strongSelfQueue->_settings.configInstanceIDToken = [token copy];
-          strongSelfQueue->_settings.configInstanceID = identity;
+      // Dispatch to the RC serial queue to update settings on the queue.
+      dispatch_async(strongSelf->_lockQueue, ^{
+        RCNConfigFetch *strongSelfQueue = weakSelf;
 
-          if (identity && !error) {
-            FIRLogInfo(kFIRLoggerRemoteConfig, @"I-RCN000022", @"Success to get iid : %@.",
-                       strongSelfQueue->_settings.configInstanceID);
-          } else {
-            FIRLogWarning(kFIRLoggerRemoteConfig, @"I-RCN000055", @"Error getting iid : %@.",
-                          error);
-          }
+        // Update config settings with the IID and token.
+        strongSelfQueue->_settings.configInstanceIDToken = [token copy];
+        strongSelfQueue->_settings.configInstanceID = identity;
+
+        if (!identity || error) {
+          NSString *errorDescription =
+              [NSString stringWithFormat:@"Error getting iid : %@.", error];
+          FIRLogError(kFIRLoggerRemoteConfig, @"I-RCN000055", @"%@",
+                      [NSString stringWithFormat:@"%@", errorDescription]);
+          return [self
+              reportCompletionOnHandler:completionHandler
+                             withStatus:FIRRemoteConfigFetchStatusFailure
+                              withError:[NSError
+                                            errorWithDomain:FIRRemoteConfigErrorDomain
+                                                       code:FIRRemoteConfigErrorInternalError
+                                                   userInfo:@{
+                                                     NSLocalizedDescriptionKey : errorDescription
+                                                   }]];
+        }
 
-          // Continue the fetch regardless of whether fetch of instance ID succeeded.
-          [strongSelfQueue fetchCheckinInfoWithCompletionHandler:completionHandler];
-        });
-      }];
+        FIRLogInfo(kFIRLoggerRemoteConfig, @"I-RCN000022", @"Success to get iid : %@.",
+                   strongSelfQueue->_settings.configInstanceID);
 
-    } else {
-      dispatch_async(self->_lockQueue, ^{
-        RCNConfigFetch *strongSelfQueue = weakSelf;
         // Continue the fetch regardless of whether fetch of instance ID succeeded.
         [strongSelfQueue fetchCheckinInfoWithCompletionHandler:completionHandler];
       });
-    }
+    }];
   };
   FIRLogDebug(kFIRLoggerRemoteConfig, @"I-RCN000039", @"Starting requesting token.");
   // Note: We expect the GCMSenderID to always be available by the time this request is made.