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[flutter_test] Add flag to send device pointer events to the framework #108430

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Merged
merged 3 commits into from
Aug 3, 2022
Merged

[flutter_test] Add flag to send device pointer events to the framework #108430

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a5f40b4
[flutter_test] Add flag to send device pointer events to the framework
jiahaog Jul 27, 2022
947c01f
Update packages/flutter_test/lib/src/binding.dart
jiahaog Jul 27, 2022
cd16176
Add invariant check, tests
jiahaog Aug 1, 2022
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44 changes: 43 additions & 1 deletion packages/flutter_test/lib/src/binding.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -494,9 +494,25 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
///
/// When [handlePointerEvent] is called directly, [pointerEventSource]
/// is [TestBindingEventSource.device].
///
/// This means that pointer events triggered by the [WidgetController] (e.g.
/// via [WidgetController.tap]) will result in actual interactions with the
/// UI, but other pointer events such as those from physical taps will be
/// dropped. See also [shouldPropagateDevicePointerEvents] if this is
/// undesired.
TestBindingEventSource get pointerEventSource => _pointerEventSource;
TestBindingEventSource _pointerEventSource = TestBindingEventSource.device;

/// Whether pointer events from [TestBindingEventSource.device] will be
/// propagated to the framework, or dropped.
///
/// Setting this can be useful to interact with the app in some other way
/// besides through the [WidgetController], such as with `adb shell input tap`
/// on Android.
///
/// See also [pointerEventSource].
bool shouldPropagateDevicePointerEvents = false;
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If we land this, we'd need ways to make sure it gets reset after tests.

The frameworks normal solution here would be to subclass the bindings. Is that still not possible in google's testing environment?

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We can subclass the binding in Google3, just that it adds a bit of complexity and I don't think it's necessary if this is more formally supported through a setting like this.

Is it important for us to reset the value though? I think users should be free to change this value wherever as some sort of "global" - whether it is in a testWidgets() or at the top of their main(), depending on their use case.

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Done in the other comment below

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nit: maybe drop the should from the name?

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@jiahaog jiahaog Jul 27, 2022 •
edited
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Effective Dart tells us to prefix it with a should though. I don't feel very strongly about this though, happy to remove it.

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How do we make sure this setting doesn't leak between tests?

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Not sure I understand, can you elaborate more on what you mean by leaking the setting?

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Basically if you have several tests in a file, and one test changes the value of this, there should be some validation at the end of the test that makes sure it is unset.

If you grep the repo for debugAssertAllPaintingVarsUnset for example, we make sure that these global sorts of things get reset at the end of each testWidgets call.

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Thanks, I'll try to add that.

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Done


/// Dispatch an event to the targets found by a hit test on its position,
/// and remember its source as [pointerEventSource].
///
Expand Down Expand Up @@ -836,6 +852,7 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
final bool autoUpdateGoldensBeforeTest = autoUpdateGoldenFiles && !isBrowser;
final TestExceptionReporter reportTestExceptionBeforeTest = reportTestException;
final ErrorWidgetBuilder errorWidgetBuilderBeforeTest = ErrorWidget.builder;
final bool shouldPropagateDevicePointerEventsBeforeTest = shouldPropagateDevicePointerEvents;

// run the test
await testBody();
Expand All @@ -854,6 +871,7 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
_verifyAutoUpdateGoldensUnset(autoUpdateGoldensBeforeTest && !isBrowser);
_verifyReportTestExceptionUnset(reportTestExceptionBeforeTest);
_verifyErrorWidgetBuilderUnset(errorWidgetBuilderBeforeTest);
_verifyShouldPropagateDevicePointerEventsUnset(shouldPropagateDevicePointerEventsBeforeTest);
_verifyInvariants();
}

Expand Down Expand Up @@ -943,6 +961,21 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
}());
}

void _verifyShouldPropagateDevicePointerEventsUnset(bool valueBeforeTest) {
assert(() {
if (shouldPropagateDevicePointerEvents != valueBeforeTest) {
FlutterError.reportError(FlutterErrorDetails(
exception: FlutterError(
'The value of shouldPropagateDevicePointerEvents was changed by the test.',
),
stack: StackTrace.current,
library: 'Flutter test framework',
));
}
return true;
}());
}

/// Called by the [testWidgets] function after a test is executed.
void postTest() {
assert(inTest);
Expand Down Expand Up @@ -1595,7 +1628,8 @@ class LiveTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
///
/// Normally, device events are silently dropped. However, if this property is
/// set to a non-null value, then the events will be routed to its
/// [HitTestDispatcher.dispatchEvent] method instead.
/// [HitTestDispatcher.dispatchEvent] method instead, unless
/// [shouldPropagateDevicePointerEvents] is true.
///
/// Events dispatched by [TestGesture] are not affected by this.
HitTestDispatcher? deviceEventDispatcher;
Expand Down Expand Up @@ -1630,6 +1664,10 @@ class LiveTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
super.handlePointerEvent(event);
break;
case TestBindingEventSource.device:
if (shouldPropagateDevicePointerEvents) {
super.handlePointerEvent(event);
break;
}
if (deviceEventDispatcher != null) {
// The pointer events received with this source has a global position
// (see [handlePointerEventForSource]). Transform it to the local
Expand All @@ -1651,6 +1689,10 @@ class LiveTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
break;
case TestBindingEventSource.device:
assert(hitTestResult != null || event is PointerAddedEvent || event is PointerRemovedEvent);
if (shouldPropagateDevicePointerEvents) {
super.dispatchEvent(event, hitTestResult);
break;
}
assert(deviceEventDispatcher != null);
if (hitTestResult != null) {
deviceEventDispatcher!.dispatchEvent(event, hitTestResult);
Expand Down
8 changes: 8 additions & 0 deletions packages/flutter_test/lib/src/widget_tester.dart
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Expand Up @@ -502,6 +502,10 @@ Future<void> expectLater(
///
/// 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].
class WidgetTester extends WidgetController implements HitTestDispatcher, TickerProvider {
WidgetTester._(super.binding) {
if (binding is LiveTestWidgetsFlutterBinding) {
Expand Down Expand Up @@ -817,6 +821,10 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
}

/// Handler for device events caught by the binding in live test mode.
///
/// [PointerDownEvent]s received here will only print a diagnostic message
/// showing possible [Finder]s that can be used to interact with the widget at
/// the location of [result].
@override
void dispatchEvent(PointerEvent event, HitTestResult result) {
if (event is PointerDownEvent) {
Expand Down
55 changes: 54 additions & 1 deletion packages/flutter_test/test/live_binding_test.dart
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Expand Up @@ -8,7 +8,7 @@ import 'package:flutter_test/flutter_test.dart';

// This file is for testings that require a `LiveTestWidgetsFlutterBinding`
void main() {
LiveTestWidgetsFlutterBinding();
final LiveTestWidgetsFlutterBinding binding = LiveTestWidgetsFlutterBinding();
testWidgets('Input PointerAddedEvent', (WidgetTester tester) async {
await tester.pumpWidget(const MaterialApp(home: Text('Test')));
await tester.pump();
Expand Down Expand Up @@ -99,4 +99,57 @@ void main() {

await expectLater(tester.binding.reassembleApplication(), completes);
}, timeout: const Timeout(Duration(seconds: 30)));

testWidgets('shouldPropagateDevicePointerEvents can override events from ${TestBindingEventSource.device}', (WidgetTester tester) async {
binding.shouldPropagateDevicePointerEvents = true;

await tester.pumpWidget(_ShowNumTaps());

final Offset position = tester.getCenter(find.text('0'));

// Simulates a real device tap.
//
// `handlePointerEventForSource defaults to sending events using
// TestBindingEventSource.device. This will not be forwarded to the actual
// gesture handlers, unless `shouldPropagateDevicePointerEvents` is true.
binding.handlePointerEventForSource(
PointerDownEvent(position: position),
);
binding.handlePointerEventForSource(
PointerUpEvent(position: position),
);

await tester.pump();

expect(find.text('1'), findsOneWidget);

// Reset the value, otherwise the test will fail when it checks that this
// has not been changed as an invariant.
binding.shouldPropagateDevicePointerEvents = false;
});
}

/// A widget that shows the number of times it has been tapped.
class _ShowNumTaps extends StatefulWidget {
@override
_ShowNumTapsState createState() => _ShowNumTapsState();
}

class _ShowNumTapsState extends State<_ShowNumTaps> {
int _counter = 0;

@override
Widget build(BuildContext context) {
return GestureDetector(
onTap: () {
setState(() {
_counter++;
});
},
child: Directionality(
textDirection: TextDirection.ltr,
child: Text(_counter.toString()),
),
);
}
}