GetX and Flutter Widget Testing: How to use Mock GetX controller?

One of the most important aspects of mobile app development is testing. Widget testing allows you to verify that your app's UI is behaving as expected and helps you catch bugs before they make it into production. With GetX, you can streamline your widget testing workflow and make it easier to write and execute tests.

In this blog post, we'll explore how you can use GetX to write efficient widget tests in Flutter especially explaining the usage of Mock controllers and Mock Getx services.

Creating a Mock Controller:

Mockito is a popular mocking library for Dart and Flutter that allows you to easily create mock objects for testing. Here's how you can install and use Mockito in your Flutter project: https://pub.dev/packages/mockito

• Open your project's pubspec.yaml file and add the following line under the dev_dependencies section:

dev_dependencies:
  flutter_test:
    sdk: flutter
  mockito: ^5.0.0

• Once you have installed the dependencies, you can start using Mockito in your tests by importing the library:

import 'package:mockito/mockito.dart';

• Now you can create a mock controller using the Mockito library. For example, let's say you have a UserController class that retrieves user data from an API. Here's how you can create a mock object for testing:

class UserControllerMock extends GetxController with Mock implements UserController {}

• Now you can inject the dependency of the mock controller using:

final userController = Get.put<UserController>(UserControllerMock());

• Now you can use this controller to perform the widget test for Widgets that are dependent on this particular controller as shown in below example test.

void main()
{

testWidgets('Validations of the text widget in Content detail page',
        (WidgetTester tester) async {
   final userController =       Get.put<UserController(UserControllerMock());
     when(userController.getUser())
      .thenAnswer((_) async => User(id: 1, name: 'John Doe'));
  await tester.pumpWidget(GetMaterialApp(
        home: UserDetailPage(),
      ));
    expect(find.text(userController.getUser().name),findsOneWidget);
    });
}

And that's it! You can now use Mockito to create and test mock objects in your Flutter project.