fix tests

flutter/test/default_integrations_test.dart

@@ -219,7 +219,9 @@ void main() {
   });
 
   test('nativeSdkIntegration adds integration', () async {
-    _channel.setMockMethodCallHandler((MethodCall methodCall) async {});
+    _channel.setMockMethodCallHandler((MethodCall methodCall) async {
+      return {'deviceId': 'test'};
+    });
 
     final integration = NativeSdkIntegration(_channel);
 

flutter/test/native_sdk_integration_test.dart

@@ -128,7 +128,9 @@ void main() {
     });
 
     test('adds integration', () async {
-      final channel = createChannelWithCallback((call) async {});
+      final channel = createChannelWithCallback((call) async {
+        return {'deviceId': 'test'};
+      });
       var sut = fixture.getSut(channel);
 
       final options = createOptions();