Reland "LiveTestWidgetsFlutterBinding support for non-touch event" (#61901)

packages/flutter_test/lib/src/binding.dart

@@ -1468,6 +1468,11 @@ class LiveTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   /// Events dispatched by [TestGesture] are not affected by this.
   HitTestDispatcher deviceEventDispatcher;
 
+
+  /// Dispatch an event to a hit test result's path.
+  ///
+  /// Apart from forwarding the event to [GestureBinding.dispatchEvent],
+  /// This also paint all events that's down on the screen.
   @override
   void dispatchEvent(
     PointerEvent event,
@@ -1476,20 +1481,19 @@ class LiveTestWidgetsFlutterBinding extends TestWidgetsFlutterBinding {
   }) {
     switch (source) {
       case TestBindingEventSource.test:
-        if (!renderView._pointers.containsKey(event.pointer)) {
-          assert(event.down || event is PointerAddedEvent);
-          if (event.down) {
-            renderView._pointers[event.pointer] = _LiveTestPointerRecord(
-              event.pointer,
-              event.position,
-            );
-          }
-        } else {
+        if (renderView._pointers.containsKey(event.pointer)) {
           renderView._pointers[event.pointer].position = event.position;
           if (!event.down)
             renderView._pointers[event.pointer].decay = _kPointerDecay;
+          _handleViewNeedsPaint();
+        } else if (event.down) {
+          assert(event is PointerDownEvent);
+          renderView._pointers[event.pointer] = _LiveTestPointerRecord(
+            event.pointer,
+            event.position,
+          );
+          _handleViewNeedsPaint();
         }
-        _handleViewNeedsPaint();
         super.dispatchEvent(event, hitTestResult, source: source);
         break;
       case TestBindingEventSource.device:

packages/flutter_test/test/live_binding_test.dart

@@ -2,7 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'dart:ui';
+
 import 'package:flutter/material.dart';
+import 'package:flutter/gestures.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 // This file is for testings that require a `LiveTestWidgetsFlutterBinding`
@@ -15,5 +18,24 @@ void main() {
     // This mimics the start of a gesture as seen on a device, where inputs
     // starts with a PointerAddedEvent.
     await gesture.addPointer();
+    // The expected result of the test is not to trigger any assert.
+  });
+
+  testWidgets('Input PointerHoverEvent', (WidgetTester tester) async {
+    PointerHoverEvent hoverEvent;
+    await tester.pumpWidget(MaterialApp(home: MouseRegion(
+      child: const Text('Test'),
+      onHover: (PointerHoverEvent event){
+        hoverEvent = event;
+      },
+    )));
+    await tester.pump();
+    final TestGesture gesture = await tester.createGesture(kind: PointerDeviceKind.mouse);
+    final Offset location = tester.getCenter(find.text('Test'));
+    // for mouse input without a down event, moveTo generates a hover event
+    await gesture.moveTo(location);
+    expect(hoverEvent, isNotNull);
+    expect(hoverEvent.position, location);
+    await gesture.removePointer();
   });
 }