Fix GlowingOverscrollIndicator examples (#155203)

Part of https://github.com/flutter/flutter/issues/130459

This pull request adds tests for the example files shown in the [GlowingOverscrollIndicator](https://api.flutter.dev/flutter/widgets/GlowingOverscrollIndicator-class.html) Flutter API reference documentation.

dev/bots/check_code_samples.dart

@@ -321,6 +321,4 @@ final Set<String> _knownMissingTests = <String>{
   'examples/api/test/widgets/interactive_viewer/interactive_viewer.constrained.0_test.dart',
   'examples/api/test/widgets/interactive_viewer/interactive_viewer.transformation_controller.0_test.dart',
   'examples/api/test/widgets/notification_listener/notification.0_test.dart',
-  'examples/api/test/widgets/overscroll_indicator/glowing_overscroll_indicator.1_test.dart',
-  'examples/api/test/widgets/overscroll_indicator/glowing_overscroll_indicator.0_test.dart',
 };

examples/api/lib/widgets/overscroll_indicator/glowing_overscroll_indicator.0.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 
 /// Flutter code sample for [GlowingOverscrollIndicator].
@@ -14,6 +15,8 @@ class GlowingOverscrollIndicatorExampleApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
+      scrollBehavior: const AlwaysGlow(),
+      theme: ThemeData(colorSchemeSeed: Colors.amber),
       home: Scaffold(
         appBar: AppBar(title: const Text('GlowingOverscrollIndicator Sample')),
         body: const GlowingOverscrollIndicatorExample(),
@@ -22,12 +25,37 @@ class GlowingOverscrollIndicatorExampleApp extends StatelessWidget {
   }
 }
 
+const Set<PointerDeviceKind> allPointers = <PointerDeviceKind>{...PointerDeviceKind.values};
+
+// Passing this class into the MaterialApp constructor ensures that a
+// GlowingOverscrollIndicator is created, regardless of the target platform.
+class AlwaysGlow extends MaterialScrollBehavior {
+  const AlwaysGlow();
+
+  @override
+  Set<PointerDeviceKind> get dragDevices => allPointers;
+
+  @override
+  Widget buildOverscrollIndicator(
+    BuildContext context,
+    Widget child,
+    ScrollableDetails details,
+  ) {
+    return GlowingOverscrollIndicator(
+      axisDirection: details.direction,
+      color: Colors.amberAccent,
+      child: child,
+    );
+  }
+}
+
 class GlowingOverscrollIndicatorExample extends StatelessWidget {
   const GlowingOverscrollIndicatorExample({super.key});
 
   @override
   Widget build(BuildContext context) {
-    final double leadingPaintOffset = MediaQuery.of(context).padding.top + AppBar().preferredSize.height;
+    final double leadingPaintOffset = MediaQuery.paddingOf(context).top + kToolbarHeight;
+
     return NotificationListener<OverscrollIndicatorNotification>(
       onNotification: (OverscrollIndicatorNotification notification) {
         if (notification.leading) {
@@ -35,17 +63,33 @@ class GlowingOverscrollIndicatorExample extends StatelessWidget {
         }
         return false;
       },
-      child: CustomScrollView(
+      child: const CustomScrollView(
         slivers: <Widget>[
-          const SliverAppBar(title: Text('Custom PaintOffset')),
+          SliverAppBar(title: Text('Custom PaintOffset')),
           SliverToBoxAdapter(
-            child: Container(
+            child: DefaultTextStyle(
+              style: TextStyle(
                 color: Colors.amberAccent,
-              height: 100,
+                fontSize: 24,
-              child: const Center(child: Text('Glow all day!')),
+                fontWeight: FontWeight.w600,
+              ),
+              child: ColoredBox(
+                color: Colors.grey,
+                child: SizedBox(
+                  width: double.infinity,
+                  height: 80,
+                  child: Center(child: Text('Glow all day!')),
+                ),
+              ),
+            ),
+          ),
+          SliverFillRemaining(
+            child: Icon(
+              Icons.sunny,
+              color: Colors.amberAccent,
+              size: 128,
             ),
           ),
-          const SliverFillRemaining(child: FlutterLogo()),
         ],
       ),
     );

examples/api/lib/widgets/overscroll_indicator/glowing_overscroll_indicator.1.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/gestures.dart';
 import 'package:flutter/material.dart';
 
 /// Flutter code sample for [GlowingOverscrollIndicator].
@@ -14,6 +15,8 @@ class GlowingOverscrollIndicatorExampleApp extends StatelessWidget {
   @override
   Widget build(BuildContext context) {
     return MaterialApp(
+      scrollBehavior: const AlwaysGlow(),
+      theme: ThemeData(colorSchemeSeed: Colors.amber),
       home: Scaffold(
         appBar: AppBar(title: const Text('GlowingOverscrollIndicator Sample')),
         body: const GlowingOverscrollIndicatorExample(),
@@ -22,6 +25,31 @@ class GlowingOverscrollIndicatorExampleApp extends StatelessWidget {
   }
 }
 
+const Set<PointerDeviceKind> allPointers = <PointerDeviceKind>{...PointerDeviceKind.values};
+
+// Passing this class into the MaterialApp constructor ensures that a
+// GlowingOverscrollIndicator is created, regardless of the target platform.
+class AlwaysGlow extends MaterialScrollBehavior {
+  const AlwaysGlow();
+
+  @override
+  Set<PointerDeviceKind> get dragDevices => allPointers;
+
+  @override
+  Widget buildOverscrollIndicator(
+    BuildContext context,
+    Widget child,
+    ScrollableDetails details,
+  ) {
+    return GlowingOverscrollIndicator(
+      axisDirection: details.direction,
+      color: Colors.amberAccent,
+      child: child,
+    );
+  }
+}
+
+
 class GlowingOverscrollIndicatorExample extends StatelessWidget {
   const GlowingOverscrollIndicatorExample({super.key});
 
@@ -33,16 +61,32 @@ class GlowingOverscrollIndicatorExample extends StatelessWidget {
           SliverAppBar(title: Text('Custom NestedScrollViews')),
         ];
       },
-      body: CustomScrollView(
+      body: const CustomScrollView(
         slivers: <Widget>[
           SliverToBoxAdapter(
-            child: Container(
+            child: DefaultTextStyle(
+              style: TextStyle(
                 color: Colors.amberAccent,
-              height: 100,
+                fontSize: 24,
-              child: const Center(child: Text('Glow all day!')),
+                fontWeight: FontWeight.w600,
+              ),
+              child: ColoredBox(
+                color: Colors.grey,
+                child: SizedBox(
+                  width: double.infinity,
+                  height: 80,
+                  child: Center(child: Text('Glow all day!')),
+                ),
+              ),
+            ),
+          ),
+          SliverFillRemaining(
+            child: Icon(
+              Icons.sunny,
+              color: Colors.amberAccent,
+              size: 128,
             ),
           ),
-          const SliverFillRemaining(child: FlutterLogo()),
         ],
       ),
     );

examples/api/test/widgets/overscroll_indicator/glowing_overscroll_indicator.0_test.dart

@@ -0,0 +1,85 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter_api_samples/widgets/overscroll_indicator/glowing_overscroll_indicator.0.dart' as example;
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('Displays widget tree when the example app is run', (WidgetTester tester) async {
+    await tester.pumpWidget(const example.GlowingOverscrollIndicatorExampleApp());
+
+    expect(find.descendant(
+      of: find.byType(Scaffold),
+      matching: find.widgetWithText(AppBar, 'GlowingOverscrollIndicator Sample'),
+    ), findsOne);
+
+    final Finder customScrollViewFinder = find.byType(CustomScrollView);
+    final Finder sliverAppBarFinder = find.descendant(
+      of: customScrollViewFinder,
+      matching: find.widgetWithText(SliverAppBar, 'Custom PaintOffset'),
+    );
+
+    expect(sliverAppBarFinder, findsOne);
+
+    expect(find.descendant(
+      of: customScrollViewFinder,
+      matching: find.widgetWithText(Center, 'Glow all day!'),
+    ), findsOne);
+
+    expect(find.descendant(
+      of: customScrollViewFinder,
+      matching: find.byType(SliverToBoxAdapter),
+    ), findsOne);
+
+    expect(find.descendant(
+      of: customScrollViewFinder,
+      matching: find.widgetWithIcon(SliverFillRemaining, Icons.sunny),
+    ), findsOne);
+
+    expect(find.descendant(
+      of: customScrollViewFinder,
+      matching: find.byType(GlowingOverscrollIndicator),
+    ), findsOne);
+
+    // Check if GlowingOverscrollIndicator overlays the SliverAppBar.
+    final RenderBox overscrollIndicator = tester.renderObject<RenderBox>(
+      find.descendant(
+        of: customScrollViewFinder,
+        matching: find.byType(GlowingOverscrollIndicator),
+      ),
+    );
+    final RenderSliver sliverAppBar = tester.renderObject<RenderSliver>(sliverAppBarFinder);
+    final Matrix4 transform = overscrollIndicator.getTransformTo(sliverAppBar);
+    final Offset? offset = MatrixUtils.getAsTranslation(transform);
+    expect(offset?.dy, 0);
+  });
+
+  testWidgets('Triggers a notification listener when the screen is dragged', (WidgetTester tester) async {
+    bool overscrollNotified = false;
+    double leadingPaintOffset = 0.0;
+
+    await tester.pumpWidget(
+      NotificationListener<OverscrollIndicatorNotification>(
+        onNotification: (OverscrollIndicatorNotification notification) {
+          overscrollNotified = true;
+          leadingPaintOffset = notification.paintOffset;
+          return false;
+        },
+        child: const example.GlowingOverscrollIndicatorExampleApp(),
+      ),
+    );
+
+    expect(leadingPaintOffset, 0);
+    expect(overscrollNotified, isFalse);
+    final BuildContext context = tester.element(find.byType(MaterialApp));
+
+    await tester.drag(find.byType(CustomScrollView), const Offset(0, 500));
+    await tester.pump();
+
+    expect(leadingPaintOffset, MediaQuery.paddingOf(context).top + kToolbarHeight);
+    expect(overscrollNotified, isTrue);
+  });
+}

examples/api/test/widgets/overscroll_indicator/glowing_overscroll_indicator.1_test.dart

@@ -0,0 +1,60 @@
+// Copyright 2014 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter_api_samples/widgets/overscroll_indicator/glowing_overscroll_indicator.1.dart' as example;
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('Displays widget tree when the example app is run', (WidgetTester tester) async {
+    await tester.pumpWidget(const example.GlowingOverscrollIndicatorExampleApp());
+
+    expect(find.descendant(
+      of: find.byType(Scaffold),
+      matching: find.widgetWithText(AppBar, 'GlowingOverscrollIndicator Sample'),
+    ), findsOne);
+
+    expect(find.descendant(
+      of: find.byType(NestedScrollView),
+      matching: find.widgetWithText(SliverAppBar, 'Custom NestedScrollViews'),
+    ), findsOne);
+
+    expect(find.descendant(
+      of: find.byType(NestedScrollView),
+      matching: find.widgetWithText(Center, 'Glow all day!'),
+    ), findsOne);
+
+    final Finder customScrollViewFinder = find.byType(CustomScrollView);
+
+    expect(find.descendant(
+      of: customScrollViewFinder,
+      matching: find.byType(SliverToBoxAdapter),
+    ), findsOne);
+
+    expect(find.descendant(
+      of: customScrollViewFinder,
+      matching: find.widgetWithIcon(SliverFillRemaining, Icons.sunny),
+    ), findsOne);
+
+    expect(find.descendant(
+      of: customScrollViewFinder,
+      matching: find.byType(GlowingOverscrollIndicator),
+    ), findsOne);
+
+    // Check if GlowingOverscrollIndicator starts just after the SliverAppBar.
+    final RenderBox overscrollIndicator = tester.renderObject<RenderBox>(
+      find.descendant(
+        of: customScrollViewFinder,
+        matching: find.byType(GlowingOverscrollIndicator),
+      ),
+    );
+    final RenderSliver sliverAppBar = tester.renderObject<RenderSliver>(
+      find.widgetWithText(SliverAppBar, 'Custom NestedScrollViews'),
+    );
+    final Matrix4 transform = overscrollIndicator.getTransformTo(sliverAppBar);
+    final Offset? offset = MatrixUtils.getAsTranslation(transform);
+    expect(offset?.dy, sliverAppBar.geometry?.paintExtent);
+  });
+}