Adapt markNeedsSemanticsUpdate algorithm to new semantics tree compiler (#13274)

* ensures that only semantics boundaries will be added to owner._nodesNeedingSemantics as expected by compiler.
* no longer throws assert if markNeedsSemanticsUpdate is called on non-semantic-boundary render object with a non-semantic-boundary parent.
* Fixes #13109.
* removes onlyLocalUpdates from markNeedsSemanticsUpdate as its no longer needed.

packages/flutter/lib/src/cupertino/switch.dart

@@ -214,7 +214,7 @@ class _RenderCupertinoSwitch extends RenderConstrainedBox {
     if (value == _value)
       return;
     _value = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+    markNeedsSemanticsUpdate();
     _position
       ..curve = Curves.ease
       ..reverseCurve = Curves.ease.flipped;

packages/flutter/lib/src/material/toggleable.dart

@@ -122,7 +122,7 @@ abstract class RenderToggleable extends RenderConstrainedBox {
     if (value == _value)
       return;
     _value = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+    markNeedsSemanticsUpdate();
     _position
       ..curve = Curves.easeIn
       ..reverseCurve = Curves.easeOut;

packages/flutter/lib/src/rendering/object.dart

@@ -2201,81 +2201,53 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
 
   /// Mark this node as needing an update to its semantics description.
   ///
-  /// `onlyLocalUpdates` should be set to true to reduce cost if the semantics
-  /// update does not in any way change the shape of the semantics tree (e.g.
-  /// [SemanticsNode]s will neither be added/removed from the tree nor be moved
-  /// within the tree). In other words, with `onlyLocalUpdates` the
-  /// [RenderObject] can indicate that it only wants to perform updates on the
-  /// local [SemanticsNode] (e.g. changing a label or flag) without affecting
-  /// other nodes in the tree.
-  ///
-  /// `onlyLocalUpdates` has to be set to false in the following cases as they
-  /// will change the shape of the tree:
-  ///
-  /// 1. [isSemanticBoundary] changed its value.
-  /// 2. [semanticsAnnotator] changed from or to returning null and
-  ///    [isSemanticBoundary] isn't true.
-  ///
-  /// If `onlyLocalUpdates` is incorrectly set to true, asserts
-  /// might throw or the computed semantics tree might be out-of-date without
-  /// warning.
-  void markNeedsSemanticsUpdate({ bool onlyLocalUpdates: false }) {
+  /// This must be called whenever the semantics configuration of this
+  /// [RenderObject] as annotated by [describeSemanticsConfiguration] changes in
+  /// any way to update the semantics tree.
+  void markNeedsSemanticsUpdate() {
     assert(!attached || !owner._debugDoingSemantics);
-    _cachedSemanticsConfiguration = null;
     if ((attached && owner._semanticsOwner == null))
       return;
-    if (onlyLocalUpdates) {
-      // The shape of the tree didn't change, but the details did.
-      // If we have our own SemanticsNode (our _semantics isn't null)
-      // then mark ourselves dirty. If we don't then we are using an
-      // ancestor's; mark all the nodes up to that one dirty.
-      RenderObject node = this;
-      while (node._semantics == null && node.parent is RenderObject) {
-        if (node._needsSemanticsUpdate)
-          return;
-        node._cachedSemanticsConfiguration = null;
-        node._needsSemanticsUpdate = true;
-        node = node.parent;
-      }
-      if (!node._needsSemanticsUpdate) {
-        node._needsSemanticsUpdate = true;
-        node._cachedSemanticsConfiguration = null;
-        if (owner != null) {
-          owner._nodesNeedingSemantics.add(node);
-          owner.requestVisualUpdate();
-        }
-      }
-    } else {
-      // The shape of the semantics tree around us may have changed.
-      // The worst case is that we may have removed a branch of the
-      // semantics tree, because when that happens we have to go up
-      // and dirty the nearest _semantics-laden ancestor of the
-      // affected node to rebuild the tree.
-      RenderObject node = this;
-      do {
-        if (node.parent is! RenderObject)
-          break;
-        node._needsSemanticsUpdate = true;
+
+    // Dirty the semantics tree starting at `this` until we have reached a
+    // RenderObject that is a semantics boundary. All semantics past this
+    // RenderObject are still up-to date. Therefore, we will later only rebuild
+    // the semantics subtree starting at th identified semantics boundary.
+
+    final bool wasSemanticsBoundary = _cachedSemanticsConfiguration?.isSemanticBoundary == true;
+    _cachedSemanticsConfiguration = null;
+    bool isEffectiveSemanticsBoundary = _semanticsConfiguration.isSemanticBoundary && wasSemanticsBoundary;
+    RenderObject node = this;
+
+    while (!isEffectiveSemanticsBoundary && node.parent is RenderObject) {
+      if (node != this && node._needsSemanticsUpdate)
+        break;
+      node._needsSemanticsUpdate = true;
+
+      node = node.parent;
+      node._cachedSemanticsConfiguration = null;
+      isEffectiveSemanticsBoundary = node._semanticsConfiguration.isSemanticBoundary;
+    }
+    if (node != this && _semantics != null && _needsSemanticsUpdate) {
+      // If `this` node has already been added to [owner._nodesNeedingSemantics]
+      // remove it as it is no longer guaranteed that its semantics
+      // node will continue to be in the tree. If it still is in the tree, the
+      // ancestor `node` added to [owner._nodesNeedingSemantics] at the end of
+      // this block will ensure that the semantics of `this` node actually get
+      // updated.
+      // (See semantics_10_test.dart for an example why this is required).
+      owner._nodesNeedingSemantics.remove(this);
+    }
+    if (!node._needsSemanticsUpdate) {
+      if (node != this) {
+        // Reset for `this` happened above already.
         node._cachedSemanticsConfiguration = null;
-        node = node.parent;
-      } while (node._semantics == null);
-      if (node != this && _semantics != null && _needsSemanticsUpdate) {
-        // If [this] node has already been added to [owner._nodesNeedingSemantics]
-        // remove it as it is no longer guaranteed that its semantics
-        // node will continue to be in the tree. If it still is in the tree, the
-        // ancestor [node] added to [owner._nodesNeedingSemantics] at the end of
-        // this block will ensure that the semantics of [this] node actually get
-        // updated.
-        // (See semantics_10_test.dart for an example why this is required).
-        owner._nodesNeedingSemantics.remove(this);
       }
-      if (!node._needsSemanticsUpdate) {
-        node._cachedSemanticsConfiguration = null;
-        node._needsSemanticsUpdate = true;
-        if (owner != null) {
-          owner._nodesNeedingSemantics.add(node);
-          owner.requestVisualUpdate();
-        }
+      node._needsSemanticsUpdate = true;
+      if (owner != null) {
+        assert(node._semanticsConfiguration.isSemanticBoundary || node.parent is! RenderObject);
+        owner._nodesNeedingSemantics.add(node);
+        owner.requestVisualUpdate();
       }
     }
   }

packages/flutter/lib/src/rendering/proxy_box.dart

@@ -992,7 +992,7 @@ abstract class _RenderCustomClip<T> extends RenderProxyBox {
   void _markNeedsClip() {
     _clip = null;
     markNeedsPaint();
-    markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+    markNeedsSemanticsUpdate();
   }
 
   T get _defaultClip;
@@ -3003,7 +3003,7 @@ class RenderSemanticsGestureHandler extends RenderProxyBox {
     if (setEquals<SemanticsAction>(value, _validActions))
       return;
     _validActions = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+    markNeedsSemanticsUpdate();
   }
 
    /// Called when the user taps on the render object.
@@ -3012,11 +3012,10 @@ class RenderSemanticsGestureHandler extends RenderProxyBox {
   set onTap(GestureTapCallback value) {
     if (_onTap == value)
       return;
-    final bool hadHandlers = _hasHandlers;
     final bool hadHandler = _onTap != null;
     _onTap = value;
     if ((value != null) != hadHandler)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: _hasHandlers == hadHandlers);
+      markNeedsSemanticsUpdate();
   }
 
   /// Called when the user presses on the render object for a long period of time.
@@ -3025,11 +3024,10 @@ class RenderSemanticsGestureHandler extends RenderProxyBox {
   set onLongPress(GestureLongPressCallback value) {
     if (_onLongPress == value)
       return;
-    final bool hadHandlers = _hasHandlers;
     final bool hadHandler = _onLongPress != null;
     _onLongPress = value;
     if ((value != null) != hadHandler)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: _hasHandlers == hadHandlers);
+      markNeedsSemanticsUpdate();
   }
 
   /// Called when the user scrolls to the left or to the right.
@@ -3038,11 +3036,10 @@ class RenderSemanticsGestureHandler extends RenderProxyBox {
   set onHorizontalDragUpdate(GestureDragUpdateCallback value) {
     if (_onHorizontalDragUpdate == value)
       return;
-    final bool hadHandlers = _hasHandlers;
     final bool hadHandler = _onHorizontalDragUpdate != null;
     _onHorizontalDragUpdate = value;
     if ((value != null) != hadHandler)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: _hasHandlers == hadHandlers);
+      markNeedsSemanticsUpdate();
   }
 
   /// Called when the user scrolls up or down.
@@ -3051,11 +3048,10 @@ class RenderSemanticsGestureHandler extends RenderProxyBox {
   set onVerticalDragUpdate(GestureDragUpdateCallback value) {
     if (_onVerticalDragUpdate == value)
       return;
-    final bool hadHandlers = _hasHandlers;
     final bool hadHandler = _onVerticalDragUpdate != null;
     _onVerticalDragUpdate = value;
     if ((value != null) != hadHandler)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: _hasHandlers == hadHandlers);
+      markNeedsSemanticsUpdate();
   }
 
   /// The fraction of the dimension of this render box to use when
@@ -3296,9 +3292,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set checked(bool value) {
     if (checked == value)
       return;
-    final bool hadValue = checked != null;
     _checked = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// If non-null, sets the [SemanticsNode.isSelected] semantic to the given
@@ -3308,9 +3303,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set selected(bool value) {
     if (selected == value)
       return;
-    final bool hadValue = selected != null;
     _selected = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// If non-null, sets the [SemanticsNode.isButton] semantic to the given value.
@@ -3319,9 +3313,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set button(bool value) {
     if (button == value)
       return;
-    final bool hadValue = button != null;
     _button = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// If non-null, sets the [SemanticsNode.label] semantic to the given value.
@@ -3332,9 +3325,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set label(String value) {
     if (_label == value)
       return;
-    final bool hadValue = _label != null;
     _label = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// If non-null, sets the [SemanticsNode.value] semantic to the given value.
@@ -3345,9 +3337,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set value(String value) {
     if (_value == value)
       return;
-    final bool hadValue = _value != null;
     _value = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// If non-null, sets the [SemanticsNode.increasedValue] semantic to the given
@@ -3359,9 +3350,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set increasedValue(String value) {
     if (_increasedValue == value)
       return;
-    final bool hadValue = _increasedValue != null;
     _increasedValue = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// If non-null, sets the [SemanticsNode.decreasedValue] semantic to the given
@@ -3373,9 +3363,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set decreasedValue(String value) {
     if (_decreasedValue == value)
       return;
-    final bool hadValue = _decreasedValue != null;
     _decreasedValue = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// If non-null, sets the [SemanticsNode.hint] semantic to the given value.
@@ -3386,9 +3375,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set hint(String value) {
     if (_hint == value)
       return;
-    final bool hadValue = _hint != null;
     _hint = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// If non-null, sets the [SemanticsNode.textDirection] semantic to the given value.
@@ -3400,9 +3388,8 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
   set textDirection(TextDirection value) {
     if (textDirection == value)
       return;
-    final bool hadValue = textDirection != null;
     _textDirection = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: (value != null) == hadValue);
+    markNeedsSemanticsUpdate();
   }
 
   /// The handler for [SemanticsAction.tap].
@@ -3421,7 +3408,7 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     final bool hadValue = _onTap != null;
     _onTap = handler;
     if ((handler != null) == hadValue)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      markNeedsSemanticsUpdate();
   }
 
   /// The handler for [SemanticsAction.longPress].
@@ -3440,7 +3427,7 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     final bool hadValue = _onLongPress != null;
     _onLongPress = handler;
     if ((handler != null) != hadValue)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      markNeedsSemanticsUpdate();
   }
 
   /// The handler for [SemanticsAction.scrollLeft].
@@ -3462,7 +3449,7 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     final bool hadValue = _onScrollLeft != null;
     _onScrollLeft = handler;
     if ((handler != null) != hadValue)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      markNeedsSemanticsUpdate();
   }
 
   /// The handler for [SemanticsAction.scrollRight].
@@ -3484,7 +3471,7 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     final bool hadValue = _onScrollRight != null;
     _onScrollRight = handler;
     if ((handler != null) != hadValue)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      markNeedsSemanticsUpdate();
   }
 
   /// The handler for [SemanticsAction.scrollUp].
@@ -3506,7 +3493,7 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     final bool hadValue = _onScrollUp != null;
     _onScrollUp = handler;
     if ((handler != null) != hadValue)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      markNeedsSemanticsUpdate();
   }
 
   /// The handler for [SemanticsAction.scrollDown].
@@ -3528,7 +3515,7 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     final bool hadValue = _onScrollDown != null;
     _onScrollDown = handler;
     if ((handler != null) != hadValue)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      markNeedsSemanticsUpdate();
   }
 
   /// The handler for [SemanticsAction.increase].
@@ -3547,7 +3534,7 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     final bool hadValue = _onIncrease != null;
     _onIncrease = handler;
     if ((handler != null) != hadValue)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      markNeedsSemanticsUpdate();
   }
 
   /// The handler for [SemanticsAction.decrease].
@@ -3566,20 +3553,11 @@ class RenderSemanticsAnnotations extends RenderProxyBox {
     final bool hadValue = _onDecrease != null;
     _onDecrease = handler;
     if ((handler != null) != hadValue)
-      markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      markNeedsSemanticsUpdate();
   }
 
   @override
   void describeSemanticsConfiguration(SemanticsConfiguration config) {
-    assert(
-      onIncrease == null || (value == null) == (increasedValue == null),
-      'If "onIncrease" is set either both "value" and "increasedValue" or neither have to be set.',
-    );
-    assert(
-      onDecrease == null || (value == null) == (decreasedValue == null),
-      'If "onDecrease" is set either both "value" and "decreasedValue" or neither have to be set.',
-    );
-
     config.isSemanticBoundary = container;
     config.explicitChildNodes = explicitChildNodes;
 

packages/flutter/test/rendering/object_test.dart

@@ -21,21 +21,6 @@ void main() {
     renderObject.markNeedsSemanticsUpdate();
     expect(onNeedVisualUpdateCallCount, 2);
   });
-
-  test('ensure frame is scheduled for markNeedsSemanticsUpdate with onlyChanges: true', () {
-    final TestRenderObject renderObject = new TestRenderObject();
-    int onNeedVisualUpdateCallCount = 0;
-    final PipelineOwner owner = new PipelineOwner(onNeedVisualUpdate: () {
-      onNeedVisualUpdateCallCount +=1;
-    });
-    owner.ensureSemantics();
-    renderObject.attach(owner);
-    owner.flushSemantics();
-
-    expect(onNeedVisualUpdateCallCount, 1);
-    renderObject.markNeedsSemanticsUpdate(onlyLocalUpdates: true);
-    expect(onNeedVisualUpdateCallCount, 2);
-  });
 }
 
 class TestRenderObject extends RenderObject {

packages/flutter/test/rendering/simple_semantics_test.dart

@@ -30,7 +30,7 @@ void main() {
 
     // Initial render does semantics.
     expect(semanticsUpdateCount, 1);
-    expect(testRender.describeSemanticsConfigurationCallCount, isNot(0));
+    expect(testRender.describeSemanticsConfigurationCallCount, isPositive);
 
     testRender.describeSemanticsConfigurationCallCount = 0;
     semanticsUpdateCount = 0;
@@ -41,7 +41,7 @@ void main() {
 
     // Object is asked for semantics, but no update is sent.
     expect(semanticsUpdateCount, 0);
-    expect(testRender.describeSemanticsConfigurationCallCount, 1);
+    expect(testRender.describeSemanticsConfigurationCallCount, isPositive);
 
     testRender.describeSemanticsConfigurationCallCount = 0;
     semanticsUpdateCount = 0;
@@ -53,7 +53,7 @@ void main() {
 
     // Object is asked for semantics, and update is sent.
     expect(semanticsUpdateCount, 1);
-    expect(testRender.describeSemanticsConfigurationCallCount, 1);
+    expect(testRender.describeSemanticsConfigurationCallCount, isPositive);
 
     semanticsHandle.dispose();
   });

packages/flutter/test/semantics/semantics_test.dart

@@ -60,7 +60,7 @@ void main() {
       expect(node.getSemanticsData().tags, tags);
     });
 
-    test('after markNeedsSemanticsUpdate(onlyLocalUpdates: true) all render objects between two semantic boundaries are asked for annotations', () {
+    test('after markNeedsSemanticsUpdate() all render objects between two semantic boundaries are asked for annotations', () {
       renderer.pipelineOwner.ensureSemantics();
 
       TestRender middle;
@@ -92,7 +92,7 @@ void main() {
       expect(root.debugSemantics.getSemanticsData().actions, expectedActions);
 
       middle.action = SemanticsAction.scrollDown;
-      middle.markNeedsSemanticsUpdate(onlyLocalUpdates: true);
+      middle.markNeedsSemanticsUpdate();
 
       pumpFrame(phase: EnginePhase.flushSemantics);
 

packages/flutter/test/widgets/keep_alive_test.dart

@@ -223,7 +223,6 @@ void main() {
       '       └─child: RenderSemanticsGestureHandler#00000\n'
       '         │ parentData: <none> (can use size)\n'
       '         │ constraints: BoxConstraints(w=800.0, h=600.0)\n'
-      '         │ semantic boundary\n'
       '         │ size: Size(800.0, 600.0)\n'
       '         │ gestures: vertical scroll\n'
       '         │\n'
@@ -328,7 +327,6 @@ void main() {
       '       └─child: RenderSemanticsGestureHandler#00000\n'
       '         │ parentData: <none> (can use size)\n'
       '         │ constraints: BoxConstraints(w=800.0, h=600.0)\n'
-      '         │ semantic boundary\n'
       '         │ size: Size(800.0, 600.0)\n'
       '         │ gestures: vertical scroll\n'
       '         │\n'

packages/flutter/test/widgets/modal_barrier_test.dart

@@ -104,11 +104,11 @@ void main() {
     final TestSemantics expectedSemantics = new TestSemantics.root(
       children: <TestSemantics>[
         new TestSemantics.rootChild(
-          id: 1,
+          id: 3,
           rect: TestSemantics.fullScreen,
           children: <TestSemantics>[
             new TestSemantics(
-              id: 2,
+              id: 4,
               rect: TestSemantics.fullScreen,
               actions: SemanticsAction.tap.index,
             ),

packages/flutter/test/widgets/semantics_10_test.dart

@@ -9,10 +9,8 @@ import 'package:flutter_test/flutter_test.dart';
 
 import 'semantics_tester.dart';
 
-List<String> callLog = <String>[];
-
 void main() {
-  testWidgets('can call markNeedsSemanticsUpdate(onlyChanges: true) followed by markNeedsSemanticsUpdate(onlyChanges: false)', (WidgetTester tester) async {
+  testWidgets('can cease to be semantics boundary after markNeedsSemanticsUpdate() has already been called once', (WidgetTester tester) async {
     final SemanticsTester semantics = new SemanticsTester(tester);
 
     await tester.pumpWidget(
@@ -23,8 +21,6 @@ void main() {
       ),
     );
 
-    callLog.clear();
-
     // The following should not trigger an assert.
     await tester.pumpWidget(
       buildTestWidgets(
@@ -34,8 +30,6 @@ void main() {
       ),
     );
 
-    expect(callLog, <String>['markNeedsSemanticsUpdate(onlyChanges: true)', 'markNeedsSemanticsUpdate(onlyChanges: false)']);
-
     semantics.dispose();
   });
 }
@@ -109,22 +103,20 @@ class RenderTest extends RenderProxyBox {
 
   }
 
-  String _label;
+  String _label = '<>';
   set label(String value) {
     if (value == _label)
       return;
     _label = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: true);
-    callLog.add('markNeedsSemanticsUpdate(onlyChanges: true)');
+    markNeedsSemanticsUpdate();
   }
 
 
-  bool _isSemanticBoundary;
+  bool _isSemanticBoundary = false;
   set isSemanticBoundary(bool value) {
     if (_isSemanticBoundary == value)
       return;
     _isSemanticBoundary = value;
-    markNeedsSemanticsUpdate(onlyLocalUpdates: false);
-    callLog.add('markNeedsSemanticsUpdate(onlyChanges: false)');
+    markNeedsSemanticsUpdate();
   }
 }

packages/flutter/test/widgets/semantics_11_test.dart

+// Copyright 2017 The Chromium 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/widgets.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'semantics_tester.dart';
+
+void main() {
+  testWidgets('markNeedsSemanticsUpdate() called on non-boundary with non-boundary parent', (WidgetTester tester) async {
+    final SemanticsTester semantics = new SemanticsTester(tester);
+
+    await tester.pumpWidget(
+      const Semantics(
+        container: true,
+        onTap: dummyTapHandler,
+        child: const Semantics(
+          onTap: dummyTapHandler,
+          child: const Semantics(
+            onTap: dummyTapHandler,
+            textDirection: TextDirection.ltr,
+            label: 'foo',
+          ),
+        ),
+      ),
+    );
+
+    expect(semantics, hasSemantics(new TestSemantics.root(
+      children: <TestSemantics>[
+        new TestSemantics.rootChild(
+          id: 1,
+          actions: SemanticsAction.tap.index,
+          children: <TestSemantics>[
+            new TestSemantics(
+              id: 2,
+              actions: SemanticsAction.tap.index,
+              children: <TestSemantics>[
+                new TestSemantics(
+                  id: 3,
+                  actions: SemanticsAction.tap.index,
+                  label: 'foo',
+                )
+              ],
+            ),
+          ],
+        )
+      ],
+    ), ignoreRect: true, ignoreTransform: true));
+
+    // make a change causing call to markNeedsSemanticsUpdate()
+
+    // This should not throw an assert.
+    await tester.pumpWidget(
+      const Semantics(
+        container: true,
+        onTap: dummyTapHandler,
+        child: const Semantics(
+          onTap: dummyTapHandler,
+          child: const Semantics(
+            onTap: dummyTapHandler,
+            textDirection: TextDirection.ltr,
+            label: 'bar',  // <-- only change
+          ),
+        ),
+      ),
+    );
+
+    expect(semantics, hasSemantics(new TestSemantics.root(
+      children: <TestSemantics>[
+        new TestSemantics.rootChild(
+          id: 1,
+          actions: SemanticsAction.tap.index,
+          children: <TestSemantics>[
+            new TestSemantics(
+              id: 2,
+              actions: SemanticsAction.tap.index,
+              children: <TestSemantics>[
+                new TestSemantics(
+                  id: 3,
+                  actions: SemanticsAction.tap.index,
+                  label: 'bar',
+                )
+              ],
+            ),
+          ],
+        )
+      ],
+    ), ignoreRect: true, ignoreTransform: true));
+
+    semantics.dispose();
+  });
+}
+
+void dummyTapHandler() { }