Unit test sample

.dart

import 'package:test/test.dart';

void main() {
  test('Test getNews() return successfuly', () {
    //Set up

    //Set up mocked version and control what it should return "News Gotten"
    final NetworkService mockedNetworkService = NetworkService();

    final NewsService newsServiceToTest =
        NewsService(network: mockedNetworkService);

    //act
    String result = newsServiceToTest.getNews();

    //assert
    expect(result, "News Gotten");
  });

  test('Test getNews() return fails', () {
    //Set up

    //Set up mocked version and control what it should return "News failed"
    final NetworkService mockedNetworkService = NetworkService();

    final NewsService newsServiceToTest =
        NewsService(network: mockedNetworkService);

    //act
    String result = newsServiceToTest.getNews();

    //assert

    expect(result, "News failed");
  });
}

class NewsService {
  NewsService({required this.network});

  final NetworkService network;

  String getNews() {
    if (network.makeNetworkCall()) {
      return "News Gotten";
    } else {
      return "News failed";
    }
  }
}

class NetworkService {
  bool makeNetworkCall() {
    return true;
  }
}