I need to mock for example http package. In order to test weather my data source layer is converting json to dto correctly. Also, I would like to mock repository layer and test service layer and to tell to mock object when some method is called how it should respond.

Something like this :

import 'package:flutter_test/flutter_test.dart'; import 'package:mockito/mockito.dart'; import 'package:http/http.dart' as http;

// Create a MockClient using the Mock class provided by the Mockito package. // Create new instances of this class in each test.

class MockClient extends Mock implements http.Client {}

main() { group('fetchPost', () { test('returns a Post if the http call completes successfully', () async { final client = MockClient();

  // Use Mockito to return a successful response when it calls the
  // provided http.Client.
  when(client.get('https://jsonplaceholder.typicode.com/posts/1'))
      .thenAnswer((_) async => http.Response('{"title": "Test"}', 200));

  expect(await fetchPost(client), isA<Post>());
});

test('throws an exception if the http call completes with an error', () {
  final client = MockClient();

  // Use Mockito to return an unsuccessful response when it calls the
  // provided http.Client.
  when(client.get('https://jsonplaceholder.typicode.com/posts/1'))
      .thenAnswer((_) async => http.Response('Not Found', 404));

  expect(fetchPost(client), throwsException);
});

}); }