Update tests for null

Author: a-maurice

messaging/tests/android/cpp/messaging_test_util.cc

@@ -106,7 +106,7 @@ void OnTokenReceived(const char* tokenstr) {
 
 void OnRegistrationReceived(const char* registration_id) {
   flatbuffers::FlatBufferBuilder builder;
-  auto reg = builder.CreateString(registration_id);
+  auto reg = builder.CreateString(registration_id ? registration_id : "");
   auto regreceived = CreateSerializedRegistrationReceived(builder, reg);
   auto event = CreateSerializedEvent(
       builder, SerializedEventUnion_SerializedRegistrationReceived,
@@ -117,7 +117,7 @@ void OnRegistrationReceived(const char* registration_id) {
 
 void OnUnregistrationReceived(const char* registration_id) {
   flatbuffers::FlatBufferBuilder builder;
-  auto unreg = builder.CreateString(registration_id);
+  auto unreg = builder.CreateString(registration_id ? registration_id : "");
   auto unregreceived = CreateSerializedUnregistrationReceived(builder, unreg);
   auto event = CreateSerializedEvent(
       builder, SerializedEventUnion_SerializedUnregistrationReceived,

messaging/tests/ios/messaging_test_util.mm

@@ -56,12 +56,12 @@ void OnTokenReceived(const char *tokenstr) {
 
 void OnRegistrationReceived(const char *registration_id) {
   [[FIRMessaging messaging].delegate messaging:[FIRMessaging messaging]
-                        didReceiveRegistration:@(registration_id)];
+                        didReceiveRegistration:registration_id ? @(registration_id) : nil];
 }
 
 void OnUnregistrationReceived(const char *registration_id) {
   [[FIRMessaging messaging].delegate messaging:[FIRMessaging messaging]
-                                 didUnregister:@(registration_id)];
+                                 didUnregister:registration_id ? @(registration_id) : nil];
 }
 
 void SleepMessagingTest(double seconds) {