SchedulerBinding's framesEnabled state leaks between tests #141835
Description
Steps to reproduce
In a widget test, calling tester.binding.handleAppLifecycleStateChanged(AppLifecycleState.paused); in an earlier test may cause subsequent tests to fail because tester.binding.framesEnabled is not reset to true
When app lifecyclestate is paused, framesEnabled is set to false but it is not reset to initial value between tests
Expected results
tester.binding.framesEnabled should be true at the start of every test
Actual results
tester.binding.framesEnabled state can be false at the start of a test due to effects from previous unrelated tests
Code sample
Code sample
Test showing framesEnabled has leaky state:
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
void main() {
var lifecycleStateChanged = false;
testWidgets('set app lifecycle state to paused', (tester) async {
expect(tester.binding.framesEnabled, isTrue);
tester.binding.handleAppLifecycleStateChanged(AppLifecycleState.paused);
lifecycleStateChanged = true;
});
testWidgets('framesEnabled should be true', (tester) async {
// In case `testWidgets` runs out of order.
expect(lifecycleStateChanged, isTrue);
// Should pass but actually fails because of the previous test
expect(tester.binding.framesEnabled, isTrue);
});
}Example of test that fails because of framesEnabled being false:
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';
void main() {
testWidgets('set app lifecycle state to paused', (tester) async {
tester.binding.handleAppLifecycleStateChanged(AppLifecycleState.paused);
});
testWidgets('fails unless comment out previous test or uncomment line 10',
(tester) async {
// tester.binding.handleAppLifecycleStateChanged(AppLifecycleState.resumed);
await tester.createWidget(() => const SizedBox());
});
}
extension WidgetTesterExtension on WidgetTester {
Future<Widget> createWidget(Widget Function() builder) async {
late Widget result;
final testWidget = Builder(
builder: (_) {
result = builder();
return result;
},
);
await pumpWidget(testWidget);
return result;
}
}Earlier test sets app lifecycle state to paused which causes framesEnabled to be false. This causes await pumpWidget(testWidget) in the subsequent test to not do anything which causes late Widget result to never be initialised, thus causing LateInitializationError
Screenshots or Video
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Logs
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Flutter Doctor output
Doctor output
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