Testing
Flutter News Toolkit applications come with 100% test coverage out of the box. Tests are located in a parallel file structure relative to your source code, residing in a test directory that mirrors the source code lib directory. Tests are automatically run on your app using Very Good Workflows.
Changes made to your source code, such as removing advertisements, might reduce test coverage or cause existing tests to fail. We recommend maintaining 100% test coverage within your application to support stability and scalability, but your application functionality won't be compromised if you forgo 100% test coverage.
To support 100% test coverage in your application, ensure that your tests capture any changes you make to the app behavior. For example, if you implement a new widget, your_widget.dart, create a corresponding your_widget_test.dart file that properly tests the new widget's behavior.
Your Flutter app's test suite contains bloc, unit, and widget tests.
The Flutter community offers excellent testing resources to guide you in developing effective tests for your application.
Unit tests
Unit tests evaluate a single method, function, or class within your codebase. You should test that your unit behaves appropriately under all conditions under which it might be executed.
For example, news_repository_test.dart tests whether the NewsRepository class can be instantiated, handle error cases correctly, and correctly execute its behavior under both success and error conditions.
Flutter's Introduction to unit testing recipe provides further information on unit testing.
Widget tests
Widget tests verify that a single widget behaves correctly within the Flutter framework using a testing environment that enables UI interactions and behaviors.
For example the following test from bottom_nav_bar_test.dart checks that the proper behavior is executed when the user interacts with the BottomNavBar widget:
testWidgets('calls onTap when navigation bar item is tapped', (tester) async {
final completer = Completer<void>();
await tester.pumpApp(
Scaffold(
body: Container(),
bottomNavigationBar: BottomNavBar(
currentIndex: 0,
onTap: (value) => completer.complete(),
),
),
);
await tester.ensureVisible(find.byType(BottomNavigationBar));
await tester.tap(find.byIcon(Icons.home_outlined));
expect(completer.isCompleted, isTrue);
});
Flutter's Introduction to widget testing recipe provides further information on widget testing.
Bloc tests
Bloc tests verify that your app's bloc state management library behaves as expected under a variety of conditions.
A bloc test sets up the test's initial conditions, instantiates the block, and tests whether the bloc behaves as expected. The following test from analytics_bloc_test.dart checks whether the AnalyticsBloc responds appropriately to user authentication:
blocTest<AnalyticsBloc, AnalyticsState>(
'calls AnalyticsRepository.setUserId '
'with user id when user is authenticated',
setUp: () => when(() => userRepository.user)
.thenAnswer((_) => Stream.value(user)),
build: () => AnalyticsBloc(
analyticsRepository: analyticsRepository,
userRepository: userRepository,
),
verify: (_) {
verify(() => analyticsRepository.setUserId(user.id)).called(1);
},
);
The test above verifies that a mocked repository is called correctly. Depending on what bloc behavior you are testing, bloc tests can also verify that an error is thrown or that the bloc's state is correct.
The bloc library testing documentation provides a thorough introduction to testing blocs.