I’m new to unit test in flutter.
I’m trying to unit test a class.
This is my code:

class LoginRepository{

    Future<SignInResult> signIn(
          String email, String password) async {
         try {
          final result =
              await Amplify.Auth.signIn(username: email, password: password);
          return Right(result);
        } catch (e) {
          print('error sign in');
         }
      }
     }

I need to write unit tests for signIn function.

group('Test Amplify Cognito', () {
    TestWidgetsFlutterBinding.ensureInitialized();
    setUp(() async {
      try {
        final auth = MockAmplifyAuthCognito();
        await MockAmplifyClass().addPlugin(auth);
        var varv = ConfigAppStaging().amplifyConfig;
        await MockAmplifyClass().configure(jsonEncode(varv));
        safePrint('successo');
      } on PlatformException catch (e) {
        safePrint('An error occured configuring amplify ${e.toString()}');
      }
    });
    test('Sign In success', () async {
      mockUserRepository = MockUserRepository();
      mockAuthCategory = MockAuthCategory();
      mockSignInResult = MockSignInResult();
      when(() => MockAmplifyClass().Auth).thenReturn(mockAuthCategory);
      when(() async => await  mockAuthCategory.signIn(username: 'mail', password: 'password'))
          .thenAnswer((_) async => mockSignInResult);
      final results = await LoginRepository().signIn('mail', 'password');
      var value = results.fold((l) => l, (r) => r);
      expect(value, isA<SignInResult>());
     });

      });

I tried to test configuring amplify in setUp method and then mocking dependencies with mocktail package, but it doesn’t seem to work.
When i configure amplify i get ‘PlatformChannel Exception’.
How should I go about performing this test? There is another way to mock classes in flutter without using mockito or mocktail?