Why does verify(() => mockObject.someGetter) throw 'Used on a non-mockito object' even though the object is a Mock?
I'm currently writing unit tests for a Flutter app using mockito, and I'm running into an issue with verifying a getter call using the latest version of mockito (v5.x).
Here's my test setup:
@GenerateMocks([InternetConnectionChecker])
void main() {
late MockInternetConnectionChecker internetConnectionChecker;
late NetworkInfoImpl networkInfo;
setUp(() {
internetConnectionChecker = MockInternetConnectionChecker();
networkInfo = NetworkInfoImpl(internetConnectionChecker);
});
test('should check internet connection', () async {
// Arrange
when(() => internetConnectionChecker.hasConnection)
.thenAnswer((_) async => true);
// Act
final result = await networkInfo.isConnect;
// Assert
verify(() => internetConnectionChecker.hasConnection); // ❌ Throws error
expect(result, true);
});
}
Even though internetConnectionChecker is clearly a MockInternetConnectionChecker, the test throws this error:
Used on a non-mockito object
package:matcher fail
package:mockito/src/mock.dart 1155:7 _makeVerify.<fn>
test\core\network\network_info_test.dart 30:13 main.<fn>.<fn>
However, if I write it like this, it works:
verify(internetConnectionChecker.hasConnection); // ✅ Works, but discouraged?
From what I understand, using verify(() => ...) is the recommended way to ensure that the method or getter was actually called. So why does this error happen?
Ran
flutter pub run build_runner build --delete-conflicting-outputsVerified that the correct imports are used:
package:mockito/mockito.dartConfirmed the type via
print(internetConnectionChecker.runtimeType)→MockInternetConnectionChecker
Is there something special about getters in the latest versions of mockito? Or has there been a breaking change that I missed?
Answer
This error usualy means that the object you're verifying is not a Mockito mock.
To fix it, make sure the objec you're calling `verify()` on is created using `Mockito.mock()` or annotated with `@Mock`.
Example:
java
SomeClass someObject = mock(SomeClass.class);
verify(someObject).getSomething();
If someObject is not a mock Mockito can't track method calls thats why youre getting the exception.
Hope this helps Ive seen this issue come up when acidentally mixing real and mock objects in tets.