WidgetTester class

Class that programmatically interacts with widgets and the test environment.

Typically, a test uses pumpWidget to load a widget tree (in a manner very similar to how runApp works in a Flutter application). Then, methods such as tap, drag, enterText, fling, longPress, etc, can be used to interact with the application. The application runs in a FakeAsync zone, which allows time to be stepped forward deliberately; this is done using the pump method.

The expect function can then be used to examine the state of the application, typically using Finders such as those in the find namespace, and Matchers such as findsOneWidget.

testWidgets('MyWidget', (WidgetTester tester) async {
  await tester.pumpWidget(const MyWidget());
  await tester.tap(find.text('Save'));
  await tester.pump(); // allow the application to handle
  await tester.pump(const Duration(seconds: 1)); // skip past the animation
  expect(find.text('Success'), findsOneWidget);
});

For convenience, instances of this class (such as the one provided by testWidgets) can be used as the vsync for AnimationController objects.

When the binding is LiveTestWidgetsFlutterBinding, events from LiveTestWidgetsFlutterBinding.deviceEventDispatcher will be handled in dispatchEvent. Thus, using flutter run to run a test lets one tap on the screen to generate Finders relevant to the test.