Inject current `FlutterView` into tree and make available via `View.of(context)` (#116924)

* enable View.of

* tests

* ++

* greg review

* rewording

* hide view from public

packages/flutter/lib/src/widgets/binding.dart

@@ -19,6 +19,7 @@ import 'framework.dart';
 import 'platform_menu_bar.dart';
 import 'router.dart';
 import 'service_extensions.dart';
+import 'view.dart';
 import 'widget_inspector.dart';
 
 export 'dart:ui' show AppLifecycleState, Locale;
@@ -896,6 +897,22 @@ mixin WidgetsBinding on BindingBase, ServicesBinding, SchedulerBinding, GestureB
   @override
   bool get framesEnabled => super.framesEnabled && _readyToProduceFrames;
 
+  /// Used by [runApp] to wrap the provided `rootWidget` in the default [View].
+  ///
+  /// The [View] determines into what [FlutterView] the app is rendered into.
+  /// For backwards-compatibility reasons, this method currently chooses
+  /// [window] (which is a [FlutterView]) as the rendering target. This will
+  /// change in a future version of Flutter.
+  ///
+  /// The `rootWidget` widget provided to this method must not already be
+  /// wrapped in a [View].
+  Widget wrapWithDefaultView(Widget rootWidget) {
+    return View(
+      view: window,
+      child: rootWidget,
+    );
+  }
+
   /// Schedules a [Timer] for attaching the root widget.
   ///
   /// This is called by [runApp] to configure the widget tree. Consider using
@@ -1014,8 +1031,9 @@ mixin WidgetsBinding on BindingBase, ServicesBinding, SchedulerBinding, GestureB
 ///  * [WidgetsBinding.handleBeginFrame], which pumps the widget pipeline to
 ///    ensure the widget, element, and render trees are all built.
 void runApp(Widget app) {
-  WidgetsFlutterBinding.ensureInitialized()
-    ..scheduleAttachRootWidget(app)
+  final WidgetsBinding binding = WidgetsFlutterBinding.ensureInitialized();
+  binding
+    ..scheduleAttachRootWidget(binding.wrapWithDefaultView(app))
     ..scheduleWarmUpFrame();
 }
 

packages/flutter/lib/src/widgets/view.dart

+// 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 'dart:ui' show FlutterView;
+
+import 'framework.dart';
+import 'lookup_boundary.dart';
+
+/// Injects a [FlutterView] into the tree and makes it available to descendants
+/// within the same [LookupBoundary] via [View.of] and [View.maybeOf].
+///
+/// In a future version of Flutter, the functionality of this widget will be
+/// extended to actually bootstrap the render tree that is going to be rendered
+/// into the provided [view]. This will enable rendering content into multiple
+/// [FlutterView]s from a single widget tree.
+///
+/// Each [FlutterView] can be associated with at most one [View] widget in the
+/// widget tree. Two or more [View] widgets configured with the same
+/// [FlutterView] must never exist within the same widget tree at the same time.
+/// Internally, this limitation is enforced by a [GlobalObjectKey] that derives
+/// its identity from the [view] provided to this widget.
+class View extends InheritedWidget {
+  /// Injects the provided [view] into the widget tree.
+  View({required this.view, required super.child}) : super(key: GlobalObjectKey(view));
+
+  /// The [FlutterView] to be injected into the tree.
+  final FlutterView view;
+
+  @override
+  bool updateShouldNotify(View oldWidget) => view != oldWidget.view;
+
+  /// Returns the [FlutterView] that the provided `context` will render into.
+  ///
+  /// Returns null if the `context` is not associated with a [FlutterView].
+  ///
+  /// The method creates a dependency on the `context`, which will be informed
+  /// when the identity of the [FlutterView] changes (i.e. the `context` is
+  /// moved to render into a different [FlutterView] then before). The context
+  /// will not be informed when the properties on the [FlutterView] itself
+  /// change their values. To access the property values of a [FlutterView] it
+  /// is best practise to use [MediaQuery.maybeOf] instead, which will ensure
+  /// that the `context` is informed when the view properties change.
+  ///
+  /// See also:
+  ///
+  ///  * [View.of], which throws instead of returning null if no [FlutterView]
+  ///    is found.
+  static FlutterView? maybeOf(BuildContext context) {
+    return LookupBoundary.dependOnInheritedWidgetOfExactType<View>(context)?.view;
+  }
+
+  /// Returns the [FlutterView] that the provided `context` will render into.
+  ///
+  /// Throws if the `context` is not associated with a [FlutterView].
+  ///
+  /// The method creates a dependency on the `context`, which will be informed
+  /// when the identity of the [FlutterView] changes (i.e. the `context` is
+  /// moved to render into a different [FlutterView] then before). The context
+  /// will not be informed when the properties on the [FlutterView] itself
+  /// change their values. To access the property values of a [FlutterView] it
+  /// is best practise to use [MediaQuery.of] instead, which will ensure that
+  /// the `context` is informed when the view properties change.
+  ///
+  /// See also:
+  ///
+  ///  * [View.maybeOf], which throws instead of returning null if no
+  ///    [FlutterView] is found.
+  static FlutterView of(BuildContext context) {
+    final FlutterView? result = maybeOf(context);
+    assert(() {
+      if (result == null) {
+        final bool hiddenByBoundary = LookupBoundary.debugIsHidingAncestorWidgetOfExactType<View>(context);
+        final List<DiagnosticsNode> information = <DiagnosticsNode>[
+          if (hiddenByBoundary) ...<DiagnosticsNode>[
+            ErrorSummary('View.of() was called with a context that does not have access to a View widget.'),
+            ErrorDescription('The context provided to View.of() does have a View widget ancestor, but it is hidden by a LookupBoundary.'),
+          ] else ...<DiagnosticsNode>[
+            ErrorSummary('View.of() was called with a context that does not contain a View widget.'),
+            ErrorDescription('No View widget ancestor could be found starting from the context that was passed to View.of().'),
+          ],
+          ErrorDescription(
+            'The context used was:\n'
+            '  $context',
+          ),
+          ErrorHint('This usually means that the provided context is not associated with a View.'),
+        ];
+        throw FlutterError.fromParts(information);
+      }
+      return true;
+    }());
+    return result!;
+  }
+}

packages/flutter/lib/src/widgets/window.dart

+// 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.
+
+/// Placeholder to be used in a future version of Flutter.
+abstract class Window {
+  const Window._();
+}

packages/flutter/lib/widgets.dart

@@ -148,8 +148,11 @@ export 'src/widgets/transitions.dart';
 export 'src/widgets/tween_animation_builder.dart';
 export 'src/widgets/unique_widget.dart';
 export 'src/widgets/value_listenable_builder.dart';
+// TODO(goderbauer): Enable once clean-up in google3 is done.
+// export 'src/widgets/view.dart';
 export 'src/widgets/viewport.dart';
 export 'src/widgets/visibility.dart';
 export 'src/widgets/widget_inspector.dart';
 export 'src/widgets/widget_span.dart';
 export 'src/widgets/will_pop_scope.dart';
+export 'src/widgets/window.dart';

packages/flutter/test/material/debug_test.dart

@@ -8,7 +8,7 @@ import 'package:flutter_test/flutter_test.dart';
 
 void main() {
   testWidgets('debugCheckHasMaterial control test', (WidgetTester tester) async {
-    await tester.pumpWidget(const Chip(label: Text('label')));
+    await tester.pumpWidget(const Center(child: Chip(label: Text('label'))));
     final dynamic exception = tester.takeException();
     expect(exception, isFlutterError);
     final FlutterError error = exception as FlutterError;
@@ -25,7 +25,7 @@ void main() {
     expect(error.diagnostics[3], isA<DiagnosticsProperty<Element>>());
     expect(error.diagnostics[4], isA<DiagnosticsBlock>());
     expect(
-      error.toStringDeep(),
+      error.toStringDeep(), startsWith(
       'FlutterError\n'
       '   No Material widget found.\n'
       '   Chip widgets require a Material widget ancestor within the\n'
@@ -42,12 +42,13 @@ void main() {
       '   The specific widget that could not find a Material ancestor was:\n'
       '     Chip\n'
       '   The ancestors of this widget were:\n'
-      '     [root]\n',
-    );
+      '     Center\n'
+      // End of ancestor chain omitted, not relevant for test.
+    ));
   });
 
   testWidgets('debugCheckHasMaterialLocalizations control test', (WidgetTester tester) async {
-    await tester.pumpWidget(const BackButton());
+    await tester.pumpWidget(const Center(child: BackButton()));
     final dynamic exception = tester.takeException();
     expect(exception, isFlutterError);
     final FlutterError error = exception as FlutterError;
@@ -64,7 +65,7 @@ void main() {
     expect(error.diagnostics[4], isA<DiagnosticsProperty<Element>>());
     expect(error.diagnostics[5], isA<DiagnosticsBlock>());
     expect(
-      error.toStringDeep(),
+      error.toStringDeep(), startsWith(
       'FlutterError\n'
       '   No MaterialLocalizations found.\n'
       '   BackButton widgets require MaterialLocalizations to be provided\n'
@@ -78,8 +79,9 @@ void main() {
       '   ancestor was:\n'
       '     BackButton\n'
       '   The ancestors of this widget were:\n'
-      '     [root]\n',
-    );
+      '     Center\n'
+      // End of ancestor chain omitted, not relevant for test.
+    ));
   });
 
   testWidgets('debugCheckHasScaffold control test', (WidgetTester tester) async {
@@ -233,6 +235,7 @@ void main() {
       '     HeroControllerScope\n'
       '     ScrollConfiguration\n'
       '     MaterialApp\n'
+      '     View-[GlobalObjectKey TestWindow#00000]\n'
       '     [root]\n'
       '   Typically, the Scaffold widget is introduced by the MaterialApp\n'
       '   or WidgetsApp widget at the top of your application widget tree.\n'
@@ -377,6 +380,7 @@ void main() {
       '     Scaffold-[LabeledGlobalKey<ScaffoldState>#00000]\n'
       '     MediaQuery\n'
       '     Directionality\n'
+      '     View-[GlobalObjectKey TestWindow#00000]\n'
       '     [root]\n'
       '   Typically, the ScaffoldMessenger widget is introduced by the\n'
       '   MaterialApp at the top of your application widget tree.\n'

packages/flutter/test/material/scaffold_test.dart

@@ -2458,6 +2458,7 @@ void main() {
       '     Scaffold\n'
       '     MediaQuery\n'
       '     Directionality\n'
+      '     View-[GlobalObjectKey TestWindow#e6136]\n'
       '     [root]\n'
       '   Typically, the ScaffoldMessenger widget is introduced by the\n'
       '   MaterialApp at the top of your application widget tree.\n',

packages/flutter/test/material/text_field_test.dart

@@ -7390,7 +7390,6 @@ void main() {
     final dynamic exception = tester.takeException();
     expect(exception, isFlutterError);
     expect(exception.toString(), startsWith('No Material widget found.'));
-    expect(exception.toString(), endsWith(':\n  $textField\nThe ancestors of this widget were:\n  [root]'));
   });
 
   testWidgets('TextField loses focus when disabled', (WidgetTester tester) async {

packages/flutter/test/widgets/custom_multi_child_layout_test.dart

@@ -372,7 +372,8 @@ void main() {
           '   in its parent data.\n'
           '   The following child has no ID: RenderConstrainedBox#00000 NEEDS-LAYOUT NEEDS-PAINT:\n'
           '     creator: ConstrainedBox ← Container ← LayoutWithMissingId ←\n'
-          '       CustomMultiChildLayout ← Center ← [root]\n'
+          '       CustomMultiChildLayout ← Center ← View-[GlobalObjectKey\n'
+          '       TestWindow#00000] ← [root]\n'
           '     parentData: offset=Offset(0.0, 0.0); id=null\n'
           '     constraints: MISSING\n'
           '     size: MISSING\n'

packages/flutter/test/widgets/debug_test.dart

@@ -79,14 +79,13 @@ void main() {
             expect(error.diagnostics[2], isA<DiagnosticsProperty<Element>>());
             expect(
               error.toStringDeep(),
-              equalsIgnoringHashCodes(
+              startsWith(
                 'FlutterError\n'
                 '   No Table widget found.\n'
                 '   Builder widgets require a Table widget ancestor.\n'
                 '   The specific widget that could not find a Table ancestor was:\n'
                 '     Builder\n'
-                '   The ownership chain for the affected widget is: "Builder ←\n'
-                '     [root]"\n',
+                '   The ownership chain for the affected widget is: "Builder ←', // End of ownership chain omitted, not relevant for test.
               ),
             );
           }
@@ -122,15 +121,20 @@ void main() {
             );
             expect(
               error.toStringDeep(),
-              equalsIgnoringHashCodes(
+              startsWith(
                 'FlutterError\n'
                 '   No MediaQuery widget ancestor found.\n'
                 '   Builder widgets require a MediaQuery widget ancestor.\n'
                 '   The specific widget that could not find a MediaQuery ancestor\n'
                 '   was:\n'
                 '     Builder\n'
-                '   The ownership chain for the affected widget is: "Builder ←\n'
-                '     [root]"\n'
+                '   The ownership chain for the affected widget is: "Builder ←' // Full chain omitted, not relevant for test.
+              ),
+            );
+            expect(
+              error.toStringDeep(),
+              endsWith(
+                '[root]"\n' // End of ownership chain.
                 '   No MediaQuery ancestor could be found starting from the context\n'
                 '   that was passed to MediaQuery.of(). This can happen because you\n'
                 '   have not added a WidgetsApp, CupertinoApp, or MaterialApp widget\n'

packages/flutter/test/widgets/focus_manager_test.dart

@@ -1228,7 +1228,8 @@ void main() {
         equalsIgnoringHashCodes(
           'FocusManager#00000\n'
           ' │ primaryFocus: FocusNode#00000(Child 4 [PRIMARY FOCUS])\n'
-          ' │ primaryFocusCreator: Container-[GlobalKey#00000] ← [root]\n'
+          ' │ primaryFocusCreator: Container-[GlobalKey#00000] ←\n'
+          ' │   View-[GlobalObjectKey TestWindow#00000] ← [root]\n'
           ' │\n'
           ' └─rootScope: FocusScopeNode#00000(Root Focus Scope [IN FOCUS PATH])\n'
           '   │ IN FOCUS PATH\n'
@@ -1266,7 +1267,6 @@ void main() {
     });
   });
 
-
   group('Autofocus', () {
     testWidgets(
       'works when the previous focused node is detached',
@@ -1695,7 +1695,6 @@ void main() {
       debugPrint = oldDebugPrint;
     }
     final String messagesStr = messages.toString();
-    expect(messagesStr.split('\n').length, equals(58));
     expect(messagesStr, contains(RegExp(r'   └─Child 1: FocusScopeNode#[a-f0-9]{5}\(parent1 \[PRIMARY FOCUS\]\)')));
     expect(messagesStr, contains('FOCUS: Notified 2 dirty nodes'));
     expect(messagesStr, contains(RegExp(r'FOCUS: Scheduling update, current focus is null, next focus will be FocusScopeNode#.*parent1')));

packages/flutter/test/widgets/framework_test.dart

@@ -1183,13 +1183,13 @@ void main() {
     expect(exception, isFlutterError);
     expect(
       exception.toString(),
-      equalsIgnoringHashCodes(
+      startsWith(
         'The children of `MultiChildRenderObjectElement` must each has an associated render object.\n'
         'This typically means that the `_EmptyWidget` or its children\n'
         'are not a subtype of `RenderObjectWidget`.\n'
         'The following element does not have an associated render object:\n'
         '  _EmptyWidget\n'
-        'debugCreator: _EmptyWidget ← Column ← [root]',
+        'debugCreator: _EmptyWidget ← Column ← ', // Omitted end of debugCreator chain because it's irrelevant for test.
       ),
     );
   });
@@ -1216,13 +1216,13 @@ void main() {
     expect(exception, isFlutterError);
     expect(
       exception.toString(),
-      equalsIgnoringHashCodes(
+      startsWith(
         'The children of `MultiChildRenderObjectElement` must each has an associated render object.\n'
         'This typically means that the `_EmptyWidget` or its children\n'
         'are not a subtype of `RenderObjectWidget`.\n'
         'The following element does not have an associated render object:\n'
         '  _EmptyWidget\n'
-        'debugCreator: _EmptyWidget ← Column ← [root]',
+        'debugCreator: _EmptyWidget ← Column ← ', // Omitted end of debugCreator chain because it's irrelevant for test.
       ),
     );
   });

packages/flutter/test/widgets/init_state_test.dart

@@ -30,7 +30,7 @@ class TestWidgetState extends State<TestWidget> {
 void main() {
   testWidgets('initState() is called when we are in the tree', (WidgetTester tester) async {
     await tester.pumpWidget(const Parent(child: TestWidget()));
-    expect(ancestors, equals(<String>['Parent', 'RenderObjectToWidgetAdapter<RenderBox>']));
+    expect(ancestors, equals(<String>['Parent', 'View', 'RenderObjectToWidgetAdapter<RenderBox>']));
   });
 }
 

packages/flutter/test/widgets/media_query_test.dart

@@ -63,15 +63,20 @@ void main() {
     expect(error.diagnostics.last, isA<ErrorHint>());
     expect(
       error.toStringDeep(),
-      equalsIgnoringHashCodes(
+      startsWith(
         'FlutterError\n'
         '   No MediaQuery widget ancestor found.\n'
         '   Builder widgets require a MediaQuery widget ancestor.\n'
         '   The specific widget that could not find a MediaQuery ancestor\n'
         '   was:\n'
         '     Builder\n'
-        '   The ownership chain for the affected widget is: "Builder ←\n'
-        '     [root]"\n'
+        '   The ownership chain for the affected widget is: "Builder ←', // Full ownership chain omitted, not relevant for test.
+      ),
+    );
+    expect(
+      error.toStringDeep(),
+      endsWith(
+        '[root]"\n' // End of ownership chain.
         '   No MediaQuery ancestor could be found starting from the context\n'
         '   that was passed to MediaQuery.of(). This can happen because you\n'
         '   have not added a WidgetsApp, CupertinoApp, or MaterialApp widget\n'

packages/flutter/test/widgets/parent_data_test.dart

@@ -274,7 +274,7 @@ void main() {
     expect(exception, isFlutterError);
     expect(
       exception.toString(),
-      equalsIgnoringHashCodes(
+      startsWith(
         'Incorrect use of ParentDataWidget.\n'
         'The following ParentDataWidgets are providing parent data to the same RenderObject:\n'
         '- Positioned(left: 7.0, top: 6.0) (typically placed directly inside a Stack widget)\n'
@@ -283,7 +283,7 @@ void main() {
         'Usually, this indicates that at least one of the offending ParentDataWidgets listed '
         'above is not placed directly inside a compatible ancestor widget.\n'
         'The ownership chain for the RenderObject that received the parent data was:\n'
-        '  DecoratedBox ← Positioned ← Positioned ← Stack ← Directionality ← [root]',
+        '  DecoratedBox ← Positioned ← Positioned ← Stack ← Directionality ← ', // End of chain omitted, not relevant for test.
       ),
     );
 
@@ -311,7 +311,7 @@ void main() {
     expect(exception, isFlutterError);
     expect(
       exception.toString(),
-      equalsIgnoringHashCodes(
+      startsWith(
         'Incorrect use of ParentDataWidget.\n'
         'The ParentDataWidget Positioned(left: 7.0, top: 6.0) wants to apply ParentData of type '
         'StackParentData to a RenderObject, which has been set up to accept ParentData of '
@@ -320,7 +320,7 @@ void main() {
         'Typically, Positioned widgets are placed directly inside Stack widgets.\n'
         'The offending Positioned is currently placed inside a Row widget.\n'
         'The ownership chain for the RenderObject that received the incompatible parent data was:\n'
-        '  DecoratedBox ← Positioned ← Row ← DummyWidget ← Directionality ← [root]',
+        '  DecoratedBox ← Positioned ← Row ← DummyWidget ← Directionality ← ', // End of chain omitted, not relevant for test.
       ),
     );
 
@@ -410,7 +410,7 @@ void main() {
     expect(exception, isFlutterError);
     expect(
       exception.toString(),
-      equalsIgnoringHashCodes(
+      startsWith(
         'Incorrect use of ParentDataWidget.\n'
         'The ParentDataWidget Expanded(flex: 1) wants to apply ParentData of type '
         'FlexParentData to a RenderObject, which has been set up to accept ParentData of '
@@ -419,7 +419,7 @@ void main() {
         'Typically, Expanded widgets are placed directly inside Flex widgets.\n'
         'The offending Expanded is currently placed inside a Stack widget.\n'
         'The ownership chain for the RenderObject that received the incompatible parent data was:\n'
-        '  LimitedBox ← Container ← Expanded ← Stack ← Row ← Directionality ← [root]',
+        '  LimitedBox ← Container ← Expanded ← Stack ← Row ← Directionality ← ', // Omitted end of debugCreator chain because it's irrelevant for test.
       ),
     );
   });

packages/flutter/test/widgets/platform_view_test.dart

@@ -2486,7 +2486,7 @@ void main() {
 
         expect(
           tester.allWidgets.map((Widget widget) => widget.runtimeType.toString()).toList(),
-          equals(<String>['PlatformViewLink', '_PlatformViewPlaceHolder']),
+          containsAllInOrder(<String>['PlatformViewLink', '_PlatformViewPlaceHolder']),
         );
 
         onPlatformViewCreatedCallBack(createdPlatformViewId);
@@ -2495,7 +2495,7 @@ void main() {
 
         expect(
           tester.allWidgets.map((Widget widget) => widget.runtimeType.toString()).toList(),
-          equals(<String>['PlatformViewLink', 'Focus', '_FocusMarker', 'Semantics', 'PlatformViewSurface']),
+          containsAllInOrder(<String>['PlatformViewLink', 'Focus', '_FocusMarker', 'Semantics', 'PlatformViewSurface']),
         );
 
         expect(createdPlatformViewId, currentViewId + 1);
@@ -2535,7 +2535,7 @@ void main() {
 
         expect(
           tester.allWidgets.map((Widget widget) => widget.runtimeType.toString()).toList(),
-          equals(<String>['Center', 'SizedBox', 'PlatformViewLink', '_PlatformViewPlaceHolder']),
+          containsAllInOrder(<String>['Center', 'SizedBox', 'PlatformViewLink', '_PlatformViewPlaceHolder']),
         );
 
         // 'create' should not have been called by PlatformViewLink, since its
@@ -2580,7 +2580,7 @@ void main() {
 
         expect(
           tester.allWidgets.map((Widget widget) => widget.runtimeType.toString()).toList(),
-          equals(<String>['PlatformViewLink', '_PlatformViewPlaceHolder']),
+          containsAllInOrder(<String>['PlatformViewLink', '_PlatformViewPlaceHolder']),
         );
 
         // Layout should have triggered a create call. Simulate the callback
@@ -2592,7 +2592,7 @@ void main() {
 
         expect(
           tester.allWidgets.map((Widget widget) => widget.runtimeType.toString()).toList(),
-          equals(<String>['PlatformViewLink', 'Focus', '_FocusMarker', 'Semantics', 'PlatformViewSurface']),
+          containsAllInOrder(<String>['PlatformViewLink', 'Focus', '_FocusMarker', 'Semantics', 'PlatformViewSurface']),
         );
 
         expect(createdPlatformViewId, currentViewId + 1);
@@ -2678,7 +2678,7 @@ void main() {
 
         expect(
           tester.allWidgets.map((Widget widget) => widget.runtimeType.toString()).toList(),
-          equals(<String>['PlatformViewLink', '_PlatformViewPlaceHolder']),
+          containsAllInOrder(<String>['PlatformViewLink', '_PlatformViewPlaceHolder']),
         );
 
         onPlatformViewCreatedCallBack(createdPlatformViewId);
@@ -2687,7 +2687,7 @@ void main() {
 
         expect(
           tester.allWidgets.map((Widget widget) => widget.runtimeType.toString()).toList(),
-          equals(<String>['PlatformViewLink', 'Focus', '_FocusMarker', 'Semantics', 'PlatformViewSurface']),
+          containsAllInOrder(<String>['PlatformViewLink', 'Focus', '_FocusMarker', 'Semantics', 'PlatformViewSurface']),
         );
 
         expect(createdPlatformViewId, currentViewId + 1);

packages/flutter/test/widgets/slotted_render_object_widget_test.dart

@@ -219,27 +219,30 @@ void main() {
 
     expect(
       tester.renderObject(find.byType(_Diagonal)).toStringDeep(),
-      equalsIgnoringHashCodes(r'''
-_RenderDiagonal#00000 relayoutBoundary=up1
- │ creator: _Diagonal ← Align ← Directionality ← [root]
- │ parentData: offset=Offset(0.0, 0.0) (can use size)
- │ constraints: BoxConstraints(0.0<=w<=800.0, 0.0<=h<=600.0)
- │ size: Size(190.0, 220.0)
- │
- ├─topLeft: RenderConstrainedBox#00000 relayoutBoundary=up2
- │   creator: SizedBox ← _Diagonal ← Align ← Directionality ← [root]
- │   parentData: offset=Offset(0.0, 0.0) (can use size)
- │   constraints: BoxConstraints(unconstrained)
- │   size: Size(80.0, 100.0)
- │   additionalConstraints: BoxConstraints(w=80.0, h=100.0)
- │
- └─bottomRight: RenderConstrainedBox#00000 relayoutBoundary=up2
-     creator: SizedBox ← _Diagonal ← Align ← Directionality ← [root]
-     parentData: offset=Offset(80.0, 100.0) (can use size)
-     constraints: BoxConstraints(unconstrained)
-     size: Size(110.0, 120.0)
-     additionalConstraints: BoxConstraints(w=110.0, h=120.0)
-''')
+      equalsIgnoringHashCodes(
+        '_RenderDiagonal#00000 relayoutBoundary=up1\n'
+        ' │ creator: _Diagonal ← Align ← Directionality ←\n'
+        ' │   View-[GlobalObjectKey TestWindow#00000] ← [root]\n'
+        ' │ parentData: offset=Offset(0.0, 0.0) (can use size)\n'
+        ' │ constraints: BoxConstraints(0.0<=w<=800.0, 0.0<=h<=600.0)\n'
+        ' │ size: Size(190.0, 220.0)\n'
+        ' │\n'
+        ' ├─topLeft: RenderConstrainedBox#00000 relayoutBoundary=up2\n'
+        ' │   creator: SizedBox ← _Diagonal ← Align ← Directionality ←\n'
+        ' │     View-[GlobalObjectKey TestWindow#00000] ← [root]\n'
+        ' │   parentData: offset=Offset(0.0, 0.0) (can use size)\n'
+        ' │   constraints: BoxConstraints(unconstrained)\n'
+        ' │   size: Size(80.0, 100.0)\n'
+        ' │   additionalConstraints: BoxConstraints(w=80.0, h=100.0)\n'
+        ' │\n'
+        ' └─bottomRight: RenderConstrainedBox#00000 relayoutBoundary=up2\n'
+        '     creator: SizedBox ← _Diagonal ← Align ← Directionality ←\n'
+        '       View-[GlobalObjectKey TestWindow#00000] ← [root]\n'
+        '     parentData: offset=Offset(80.0, 100.0) (can use size)\n'
+        '     constraints: BoxConstraints(unconstrained)\n'
+        '     size: Size(110.0, 120.0)\n'
+        '     additionalConstraints: BoxConstraints(w=110.0, h=120.0)\n',
+      )
     );
   });
 }

packages/flutter/test/widgets/stack_test.dart

@@ -783,21 +783,27 @@ void main() {
     await tester.pumpWidget(
       Stack(),
     );
+    final String exception = tester.takeException().toString();
+
     expect(
-      tester.takeException().toString(),
+      exception, startsWith(
       'No Directionality widget found.\n'
       "Stack widgets require a Directionality widget ancestor to resolve the 'alignment' argument.\n"
       "The default value for 'alignment' is AlignmentDirectional.topStart, which requires a text direction.\n"
       'The specific widget that could not find a Directionality ancestor was:\n'
       '  Stack\n'
-      'The ownership chain for the affected widget is: "Stack ← [root]"\n'
+      'The ownership chain for the affected widget is: "Stack ← ', // Omitted full ownership chain because it is not relevant for the test.
+    ));
+    expect(
+      exception, endsWith(
+      '← [root]"\n' // End of ownership chain.
       'Typically, the Directionality widget is introduced by the MaterialApp or WidgetsApp widget at the '
       'top of your application widget tree. It determines the ambient reading direction and is used, for '
       'example, to determine how to lay out text, how to interpret "start" and "end" values, and to resolve '
       'EdgeInsetsDirectional, AlignmentDirectional, and other *Directional objects.\n'
       'Instead of providing a Directionality widget, another solution would be passing a non-directional '
       "'alignment', or an explicit 'textDirection', to the Stack.",
-    );
+    ));
   });
 
   testWidgets('Can update clipBehavior of IndexedStack',

packages/flutter/test/widgets/view_test.dart

+// 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 'dart:ui';
+
+import 'package:flutter/src/widgets/view.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('Widgets running with runApp can find View', (WidgetTester tester) async {
+    FlutterView? viewOf;
+    FlutterView? viewMaybeOf;
+
+    runApp(
+      Builder(
+        builder: (BuildContext context) {
+          viewOf = View.of(context);
+          viewMaybeOf = View.maybeOf(context);
+          return Container();
+        },
+      ),
+    );
+
+    expect(viewOf, isNotNull);
+    expect(viewOf, isA<FlutterView>());
+    expect(viewMaybeOf, isNotNull);
+    expect(viewMaybeOf, isA<FlutterView>());
+  });
+
+  testWidgets('Widgets running with pumpWidget can find View', (WidgetTester tester) async {
+    FlutterView? view;
+    FlutterView? viewMaybeOf;
+
+    await tester.pumpWidget(
+      Builder(
+        builder: (BuildContext context) {
+          view = View.of(context);
+          viewMaybeOf = View.maybeOf(context);
+          return Container();
+        },
+      ),
+    );
+
+    expect(view, isNotNull);
+    expect(view, isA<FlutterView>());
+    expect(viewMaybeOf, isNotNull);
+    expect(viewMaybeOf, isA<FlutterView>());
+  });
+
+  testWidgets('cannot find View behind a LookupBoundary', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      LookupBoundary(
+        child: Container(),
+      ),
+    );
+
+    final BuildContext context = tester.element(find.byType(Container));
+
+    expect(View.maybeOf(context), isNull);
+    expect(
+      () => View.of(context),
+      throwsA(isA<FlutterError>().having(
+        (FlutterError error) => error.message,
+        'message',
+        contains('The context provided to View.of() does have a View widget ancestor, but it is hidden by a LookupBoundary.'),
+      )),
+    );
+  });
+}

packages/flutter/test/widgets/widget_inspector_test.dart

@@ -4277,11 +4277,7 @@ class _TestWidgetInspectorService extends TestWidgetInspectorService {
         final Element element = tester.element(find.byType(Directionality).first);
         Element? root;
         element.visitAncestorElements((Element ancestor) {
-          if (root == null) {
-            root = ancestor;
-            // Stop traversing ancestors.
-            return false;
-          }
+          root = ancestor;
           return true;
         });
         expect(root, isNotNull);

packages/flutter_test/lib/src/widget_tester.dart

@@ -553,12 +553,24 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
     EnginePhase phase = EnginePhase.sendSemanticsUpdate,
   ]) {
     return TestAsyncUtils.guard<void>(() {
-      binding.attachRootWidget(widget);
-      binding.scheduleFrame();
-      return binding.pump(duration, phase);
+      return _pumpWidget(
+        binding.wrapWithDefaultView(widget),
+        duration,
+        phase,
+      );
     });
   }
 
+  Future<void> _pumpWidget(
+    Widget widget, [
+    Duration? duration,
+    EnginePhase phase = EnginePhase.sendSemanticsUpdate,
+  ]) {
+    binding.attachRootWidget(widget);
+    binding.scheduleFrame();
+    return binding.pump(duration, phase);
+  }
+
   @override
   Future<List<Duration>> handlePointerEventRecord(Iterable<PointerEventRecord> records) {
     assert(records != null);
@@ -697,7 +709,7 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
     // The interval following the last frame doesn't have to be within the fullDuration.
     Duration elapsed = Duration.zero;
     return TestAsyncUtils.guard<void>(() async {
-      binding.attachRootWidget(target);
+      binding.attachRootWidget(binding.wrapWithDefaultView(target));
       binding.scheduleFrame();
       while (elapsed < maxDuration) {
         await binding.pump(interval);
@@ -720,12 +732,14 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
       'therefore no restoration data has been collected to restore from. Did you forget to wrap '
       'your widget tree in a RootRestorationScope?',
     );
-    final Widget widget = ((binding.renderViewElement! as RenderObjectToWidgetElement<RenderObject>).widget as RenderObjectToWidgetAdapter<RenderObject>).child!;
-    final TestRestorationData restorationData = binding.restorationManager.restorationData;
-    runApp(Container(key: UniqueKey()));
-    await pump();
-    binding.restorationManager.restoreFrom(restorationData);
-    return pumpWidget(widget);
+    return TestAsyncUtils.guard<void>(() async {
+      final Widget widget = ((binding.renderViewElement! as RenderObjectToWidgetElement<RenderObject>).widget as RenderObjectToWidgetAdapter<RenderObject>).child!;
+      final TestRestorationData restorationData = binding.restorationManager.restorationData;
+      runApp(Container(key: UniqueKey()));
+      await pump();
+      binding.restorationManager.restoreFrom(restorationData);
+      return _pumpWidget(widget);
+    });
   }
 
   /// Retrieves the current restoration data from the [RestorationManager].