Setting Up Firebase Remote Config in Test in Flutter

Question

I'm trying to add firebase remote config mock to test my Flutter app. I have this file as a mock https://github.com/pusp/flutterfire/blob/c3b13af41e2fadc22a44ebbcd14a8ac4736d9e75/packages/firebase_remote_config/firebase_remote_config/test/mock.dart

typedef Callback(MethodCall call);

setupFirebaseRemoteConfigMocks([Callback customHandlers]) {
  TestWidgetsFlutterBinding.ensureInitialized();

  MethodChannelFirebase.channel.setMockMethodCallHandler((call) async {
    if (call.method == 'Firebase#initializeCore') {
      return [
        {
          'name': defaultFirebaseAppName,
          'options': {
            'apiKey': '123',
            'appId': '123',
            'messagingSenderId': '123',
            'projectId': '123',
          },
          'pluginConstants': {},
        }
      ];
    }

    if (call.method == 'Firebase#initializeApp') {
      return {
        'name': call.arguments['appName'],
        'options': call.arguments['options'],
        'pluginConstants': {},
      };
    }

    if (customHandlers != null) {
      customHandlers(call);
    }

    return null;
  });
}

and added following in setUpAll function in my Flutter test file

setUpAll(() async {
    setupFirebaseRemoteConfigMocks();
    await Firebase.initializeApp();
  });

Here is how I'm loading Firebase remote config in the source file

RemoteConfig remoteConfig = RemoteConfig.instance;
await remoteConfig.setConfigSettings(RemoteConfigSettings(
  fetchTimeout: const Duration(seconds: 10),
  minimumFetchInterval: const Duration(hours: 1),
));
await remoteConfig.fetchAndActivate();

But when I try running the test, I'm getting the following error. What could have gone wrong?

   ══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following _TypeError was thrown running a test:
type 'Null' is not a subtype of type 'int'

When the exception was thrown, this was the stack:
#0      MethodChannelFirebaseRemoteConfig.setInitialValues (package:firebase_remote_config_platform_interface/src/method_channel/method_channel_firebase_remote_config.dart:63:62)
#1      new FirebaseRemoteConfigPlatform.instanceFor (package:firebase_remote_config_platform_interface/src/platform_interface/platform_interface_firebase_remote_config.dart:32:10)
#2      RemoteConfig._delegate (package:firebase_remote_config/src/remote_config.dart:24:55)
#3      RemoteConfig._delegate (package:firebase_remote_config/src/remote_config.dart)
#4      RemoteConfig.setConfigSettings (package:firebase_remote_config/src/remote_config.dart:131:12)

Answer 1

your pluginConstants is not quite right. Try this:

'pluginConstants': {
            'plugins.flutter.io/firebase_remote_config': {
              'minimumFetchInterval': 0,
              'fetchTimeout': 0,
              'lastFetchTime': 0,
              'lastFetchStatus': 'success',
              'parameters': {}
            }
          },