* Add test_spec for FCM
* FIRMessagingRemoteNotificationsProxyTest - don't use OCMPartialMock([UIApplication sharedApplication]) to avoid crashing tests on iOS 8 (#3094)
* Migrate Firebase off @import statements
* - Migrate tests and test utils from @import to #import.
- Update Xcode projects for tests to explicitly link in framework deps.
- Update check_no_module_imports.sh to look for @imports in tests/test utils/
integration tests.
* Ensure check_no_module_imports.sh explicitly exits with code 0 on success.
FCM's swizzling of the user notification center currently swizzles only one of the two optional delegate methods (userNotificationCenter:willPresentNotification:withCompletionHandler:), but not the other (userNotificationCenter:didReceiveNotificationResponse:withCompletionHandler:).
The didReceiveNotificationResponse, if implemented by the delegate, is the sole receiver of all user action on a notification, including simply tapping on the notification itself. Prior to this change, if the developer had implemented didReceiveNotificationResponse, then FCM would not be able to collect this event for analytics.
Additionally, I changed the logic in FIRMessagingRemoteNotificationsProxy to check whether these methods are actually implemented before swizzling them. It was always swizzling, which meant it was adding an implementation if the method didn't exist. This would confuse iOS into thinking the developer did implement these methods and NOT fall back to delivering the notifications to the application delegate.
With this change, if the developer did not implement these methods, then FCM will not swizzle those methods. That keeps the behavior true to what the developer intended.
Chen Liang