I have encountered an error when trying to test my Flutter App. I have a custom widget that is at the bottom (out of the first viewport) of a CustomScrollView widget. In my test, I want to verify that it is actually there.
I have already tried to use WidgetTester.scrollUntilVisible as well as WidgetTester.drag (like it was done in the tests of the flutter framework). Additionally, I tried to refactor my tests with the FlutterDriver which just messed everything else up completely.
How do I scroll to the bottom of a CustomScrollView inside of a test?
This minimal reproduction shows the application containing the CustomScrollView which has a Container widget with the height of one screen (so that the widget I want to find is out of the initial view)
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
body: CustomScrollView(
slivers: [
SliverToBoxAdapter(
child: Container(
height: MediaQuery.of(context).size.height,
),
),
MyWidget(),
],
)),
);
}
}
class MyWidget extends StatelessWidget {
@override
Widget build(BuildContext context) {
return SliverToBoxAdapter(
child: Container(
height: 100,
width: 100,
),
);
}
}
Here is the test I initially wrote to find the widget, which failed of course.
void main() {
testWidgets('main contains mywidget', (WidgetTester tester) async {
// arange
await tester.pumpWidget(MyApp());
// act
final myWidget = find.byType(MyWidget);
// assert
expect(myWidget, findsOneWidget);
});
}
In this iteration, I used the WidgetTester.scrollUntilVisible function but got the error below.
void main() {
testWidgets('main contains mywidget', (WidgetTester tester) async {
// arange
await tester.pumpWidget(MyApp());
// act
final myWidget = find.byType(MyWidget);
final customScrollView = find.byType(CustomScrollView);
await tester.scrollUntilVisible(myWidget, 100,
scrollable: customScrollView);
await tester.pump();
// assert
expect(myWidget, findsOneWidget);
});
}
══╡ EXCEPTION CAUGHT BY FLUTTER TEST FRAMEWORK ╞════════════════════════════════════════════════════
The following _CastError was thrown running a test:
type 'CustomScrollView' is not a subtype of type 'Scrollable' in type cast
When the exception was thrown, this was the stack:
#0 WidgetController.widget (package:flutter_test/src/controller.dart:66:44)
#1 WidgetController.scrollUntilVisible.<anonymous closure> (package:flutter_test/src/controller.dart:995:15)
#2 WidgetController.scrollUntilVisible.<anonymous closure> (package:flutter_test/src/controller.dart:993:39)
#5 TestAsyncUtils.guard (package:flutter_test/src/test_async_utils.dart:72:41)
#6 WidgetController.scrollUntilVisible (package:flutter_test/src/controller.dart:993:27)
#7 main.<anonymous closure> (file:///C:/Users/X/test_example/test/main_test.dart:12:18)
<asynchronous suspension>
<asynchronous suspension>
(elided 3 frames from dart:async and package:stack_trace)
I appreciate any help or suggestions on how to fix this issue and successfully test my CustomScrollView