Refactor SemanticsData and SemanticsNode to use Diagnosticable. (#11957)

* Refactor SemanticsData and SemanticsNode to use Diagnosticable.

* Switch toStringDeep to take named parameters.

packages/flutter/lib/src/foundation/diagnostics.dart

@@ -679,7 +679,7 @@ abstract class DiagnosticsNode {
   String toString({ TextTreeConfiguration parentConfiguration }) {
     assert(style != null);
     if (style == DiagnosticsTreeStyle.singleLine)
-      return toStringDeep('', '', parentConfiguration);
+      return toStringDeep(parentConfiguration: parentConfiguration);
 
     final String description = toDescription(parentConfiguration: parentConfiguration);
 
@@ -736,7 +736,11 @@ abstract class DiagnosticsNode {
   ///  * [toString], for a brief description of the [value] but not its children.
   ///  * [toStringShallow], for a detailed description of the [value] but not its
   ///    children.
-  String toStringDeep([String prefixLineOne = '', String prefixOtherLines, TextTreeConfiguration parentConfiguration]) {
+  String toStringDeep({
+    String prefixLineOne: '',
+    String prefixOtherLines,
+    TextTreeConfiguration parentConfiguration,
+  }) {
     prefixOtherLines ??= prefixLineOne;
 
     final List<DiagnosticsNode> children = getChildren();
@@ -796,9 +800,9 @@ abstract class DiagnosticsNode {
       if (property.style != DiagnosticsTreeStyle.singleLine) {
         final TextTreeConfiguration propertyStyle = property.textTreeConfiguration;
         builder.writeRaw(property.toStringDeep(
-            '${builder.prefixOtherLines}${propertyStyle.prefixLineOne}',
-            '${builder.prefixOtherLines}${propertyStyle.linkCharacter}${propertyStyle.prefixOtherLines}',
-            config,
+            prefixLineOne: '${builder.prefixOtherLines}${propertyStyle.prefixLineOne}',
+            prefixOtherLines: '${builder.prefixOtherLines}${propertyStyle.linkCharacter}${propertyStyle.prefixOtherLines}',
+            parentConfiguration: config,
         ));
         continue;
       }
@@ -850,9 +854,9 @@ abstract class DiagnosticsNode {
         if (i == children.length - 1) {
           final String lastChildPrefixLineOne = '$prefixChildren${childConfig.prefixLastChildLineOne}';
           builder.writeRawLine(child.toStringDeep(
-            lastChildPrefixLineOne,
-            '$prefixChildren${childConfig.childLinkSpace}${childConfig.prefixOtherLines}',
-            config,
+            prefixLineOne: lastChildPrefixLineOne,
+            prefixOtherLines: '$prefixChildren${childConfig.childLinkSpace}${childConfig.prefixOtherLines}',
+            parentConfiguration: config,
           ));
           if (childConfig.footer.isNotEmpty)
             builder.writeRaw('$prefixChildren${childConfig.childLinkSpace}${childConfig.footer}');
@@ -860,7 +864,7 @@ abstract class DiagnosticsNode {
           final TextTreeConfiguration nextChildStyle = _childTextConfiguration(children[i + 1], config);
           final String childPrefixLineOne = '$prefixChildren${childConfig.prefixLineOne}';
           final String childPrefixOtherLines ='$prefixChildren${nextChildStyle.linkCharacter}${childConfig.prefixOtherLines}';
-          builder.writeRawLine(child.toStringDeep(childPrefixLineOne, childPrefixOtherLines));
+          builder.writeRawLine(child.toStringDeep(prefixLineOne: childPrefixLineOne, prefixOtherLines: childPrefixOtherLines));
           if (childConfig.footer.isNotEmpty)
             builder.writeRaw('$prefixChildren${nextChildStyle.linkCharacter}${childConfig.footer}');
         }
@@ -1249,16 +1253,18 @@ class IterableProperty<T> extends DiagnosticsProperty<Iterable<T>> {
   /// value with 0 elements would, confusingly, be displayed as the empty
   /// string. It defaults to the string `[]`.
   ///
-  /// The [style] and [hidden] arguments must also not be null.
+  /// The [style], [hidden], and [showName] arguments must also not be null.
   IterableProperty(String name, Iterable<T> value, {
     Object defaultValue: kNoDefaultValue,
     String ifNull,
     String ifEmpty: '[]',
     DiagnosticsTreeStyle style: DiagnosticsTreeStyle.singleLine,
     bool hidden: false,
+    bool showName: true,
   }) : assert(ifEmpty != null),
        assert(style != null),
        assert(hidden != null),
+       assert(showName != null),
        super(
     name,
     value,
@@ -1267,6 +1273,7 @@ class IterableProperty<T> extends DiagnosticsProperty<Iterable<T>> {
     ifEmpty: ifEmpty,
     style: style,
     hidden: hidden,
+    showName: showName,
   );
 
   @override
@@ -1634,14 +1641,19 @@ class DiagnosticsProperty<T> extends DiagnosticsNode {
   List<DiagnosticsNode> getChildren() => <DiagnosticsNode>[];
 }
 
-/// [DiagnosticsNode] for an instance of [Diagnosticable].
-class _DiagnosticableNode<T extends Diagnosticable> extends DiagnosticsNode {
-  _DiagnosticableNode({
+/// [DiagnosticsNode] that lazily calls the associated [Diagnosticable] [value]
+/// to implement [getChildren] and [getProperties].
+class DiagnosticableNode<T extends Diagnosticable> extends DiagnosticsNode {
+  /// Create a diagnostics describing a [Diagnosticable] value.
+  ///
+  /// The [value] argument must not be null.
+  DiagnosticableNode({
     String name,
     @required this.value,
     @required DiagnosticsTreeStyle style,
     String emptyBodyDescription,
-  }) : super(
+  }) : assert(value != null),
+       super(
          name: name,
          style: style,
        );
@@ -1683,7 +1695,7 @@ class _DiagnosticableNode<T extends Diagnosticable> extends DiagnosticsNode {
 }
 
 /// [DiagnosticsNode] for an instance of [DiagnosticableTree].
-class _DiagnosticableTreeNode extends _DiagnosticableNode<DiagnosticableTree> {
+class _DiagnosticableTreeNode extends DiagnosticableNode<DiagnosticableTree> {
   _DiagnosticableTreeNode({
     String name,
     @required DiagnosticableTree value,
@@ -1841,7 +1853,7 @@ abstract class Diagnosticable {
   /// relationship between the parent and the node. For example, pass
   /// [DiagnosticsTreeStyle.offstage] to indicate that a node is offstage.
   DiagnosticsNode toDiagnosticsNode({ String name, DiagnosticsTreeStyle style }) {
-    return new _DiagnosticableNode<Diagnosticable>(
+    return new DiagnosticableNode<Diagnosticable>(
       name: name,
       value: this,
       style: style,
@@ -2110,8 +2122,8 @@ abstract class DiagnosticableTree extends Diagnosticable {
   ///  * [toString], for a brief description of the object but not its children.
   ///  * [toStringShallow], for a detailed description of the object but not its
   ///    children.
-  String toStringDeep([String prefixLineOne = '', String prefixOtherLines]) {
-    return toDiagnosticsNode().toStringDeep(prefixLineOne, prefixOtherLines);
+  String toStringDeep({ String prefixLineOne: '', String prefixOtherLines }) {
+    return toDiagnosticsNode().toStringDeep(prefixLineOne: prefixLineOne, prefixOtherLines: prefixOtherLines);
   }
 
   @override
@@ -2176,8 +2188,8 @@ abstract class DiagnosticableTreeMixin implements DiagnosticableTree {
   }
 
   @override
-  String toStringDeep([String prefixLineOne = '', String prefixOtherLines]) {
-    return toDiagnosticsNode().toStringDeep(prefixLineOne, prefixOtherLines);
+  String toStringDeep({ String prefixLineOne: '', String prefixOtherLines }) {
+    return toDiagnosticsNode().toStringDeep(prefixLineOne: prefixLineOne, prefixOtherLines: prefixOtherLines);
   }
 
   @override

packages/flutter/lib/src/painting/text_span.dart

@@ -271,7 +271,7 @@ class TextSpan extends DiagnosticableTree {
           'TextSpan contains a null child.\n'
           'A TextSpan object with a non-null child list should not have any nulls in its child list.\n'
           'The full text in question was:\n'
-          '${toStringDeep('  ')}'
+          '${toStringDeep(prefixLineOne: '  ')}'
         );
       }
       return true;

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

@@ -329,7 +329,7 @@ void debugDumpLayerTree() {
 /// The order in which the children of a [SemanticsNode] will be printed is
 /// controlled by the [childOrder] parameter.
 void debugDumpSemanticsTree(DebugSemanticsDumpOrder childOrder) {
-  debugPrint(RendererBinding.instance?.renderView?.debugSemantics?.toStringDeep(childOrder) ?? 'Semantics not collected.');
+  debugPrint(RendererBinding.instance?.renderView?.debugSemantics?.toStringDeep(childOrder: childOrder) ?? 'Semantics not collected.');
 }
 
 /// A concrete binding for applications that use the Rendering framework

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

@@ -145,11 +145,15 @@ List<String> debugDescribeTransform(Matrix4 transform) {
 /// Property which handles [Matrix4] that represent transforms.
 class TransformProperty extends DiagnosticsProperty<Matrix4> {
   /// Create a diagnostics property for [Matrix4] objects.
+  ///
+  /// The [showName] argument must not be null.
   TransformProperty(String name, Matrix4 value, {
+    bool showName: true,
     Object defaultValue: kNoDefaultValue,
-  }) : super(
+  }) : assert(showName != null), super(
     name,
     value,
+    showName: showName,
     defaultValue: defaultValue,
   );
 

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

@@ -2839,11 +2839,11 @@ abstract class RenderObject extends AbstractNode with DiagnosticableTreeMixin im
   /// If the prefix argument is provided, then every line in the output
   /// will be prefixed by that string.
   @override
-  String toStringDeep([String prefixLineOne = '', String prefixOtherLines = '']) {
+  String toStringDeep({ String prefixLineOne: '', String prefixOtherLines: '' }) {
     final RenderObject debugPreviousActiveLayout = _debugActiveLayout;
     _debugActiveLayout = null;
 
-    final String result = super.toStringDeep(prefixLineOne, prefixOtherLines);
+    final String result = super.toStringDeep(prefixLineOne: prefixLineOne, prefixOtherLines: prefixOtherLines);
 
     _debugActiveLayout = debugPreviousActiveLayout;
     return result;

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

@@ -91,7 +91,7 @@ class SemanticsTag {
 ///
 /// Typically obtained from [SemanticsNode.getSemanticsData].
 @immutable
-class SemanticsData {
+class SemanticsData extends Diagnosticable {
   /// Creates a semantics data object.
   ///
   /// The [flags], [actions], [label], and [Rect] arguments must not be null.
@@ -146,25 +146,28 @@ class SemanticsData {
   bool hasAction(SemanticsAction action) => (actions & action.index) != 0;
 
   @override
-  String toString() {
-    final StringBuffer buffer = new StringBuffer();
-    buffer.write('$runtimeType($rect');
-    if (transform != null)
-      buffer.write('; $transform');
+  String toStringShort() => '$runtimeType';
+
+  @override
+  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
+    super.debugFillProperties(properties);
+    properties.add(new DiagnosticsProperty<Rect>('rect', rect, showName: false));
+    properties.add(new TransformProperty('transform', transform, showName: false, defaultValue: null));
+    final List<String> actionSummary = <String>[];
     for (SemanticsAction action in SemanticsAction.values.values) {
       if ((actions & action.index) != 0)
-        buffer.write('; $action');
+        actionSummary.add(describeEnum(action));
     }
+    properties.add(new IterableProperty<String>('actions', actionSummary, hidden: actionSummary.isEmpty));
+
+    final List<String> flagSummary = <String>[];
     for (SemanticsFlags flag in SemanticsFlags.values.values) {
       if ((flags & flag.index) != 0)
-        buffer.write('; $flag');
+        flagSummary.add(describeEnum(flag));
     }
-    if (label.isNotEmpty)
-      buffer.write('; "$label"');
-    if (textDirection != null)
-      buffer.write('; $textDirection');
-    buffer.write(')');
-    return buffer.toString();
+    properties.add(new IterableProperty<String>('flags', flagSummary, hidden: flagSummary.isEmpty));
+    properties.add(new StringProperty('label', label, defaultValue: ''));
+    properties.add(new EnumProperty<TextDirection>('textDirection', textDirection, defaultValue: null));
   }
 
   @override
@@ -185,13 +188,36 @@ class SemanticsData {
   int get hashCode => hashValues(flags, actions, label, textDirection, rect, tags, transform);
 }
 
+class _SemanticsDiagnosticableNode extends DiagnosticableNode<SemanticsNode> {
+  _SemanticsDiagnosticableNode({
+    String name,
+    @required SemanticsNode value,
+    @required DiagnosticsTreeStyle style,
+    @required this.childOrder,
+  }) : super(
+    name: name,
+    value: value,
+    style: style,
+  );
+
+  final DebugSemanticsDumpOrder childOrder;
+
+  @override
+  List<DiagnosticsNode> getChildren() {
+    if (value != null)
+      return value.debugDescribeChildren(childOrder: childOrder);
+
+    return const <DiagnosticsNode>[];
+  }
+}
+
 /// A node that represents some semantic data.
 ///
 /// The semantics tree is maintained during the semantics phase of the pipeline
 /// (i.e., during [PipelineOwner.flushSemantics]), which happens after
 /// compositing. The semantics tree is then uploaded into the engine for use
 /// by assistive technology.
-class SemanticsNode extends AbstractNode {
+class SemanticsNode extends AbstractNode with DiagnosticableTreeMixin {
   /// Creates a semantic node.
   ///
   /// Each semantic node has a unique identifier that is assigned when the node
@@ -211,7 +237,7 @@ class SemanticsNode extends AbstractNode {
     VoidCallback showOnScreen,
     SemanticsOwner owner,
   }) : id = 0,
-        _showOnScreen = showOnScreen,
+       _showOnScreen = showOnScreen,
        _actionHandler = handler {
     attach(owner);
   }
@@ -722,77 +748,87 @@ class SemanticsNode extends AbstractNode {
   }
 
   @override
-  String toString() {
-    final StringBuffer buffer = new StringBuffer();
-    buffer.write('$runtimeType($id');
-    if (_dirty)
-      buffer.write(' (${ owner != null && owner._dirtyNodes.contains(this) ? "dirty" : "STALE; owner=$owner" })');
-    if (_shouldMergeAllDescendantsIntoThisNode)
-      buffer.write(' (leaf merge)');
+  String toStringShort() => '$runtimeType#$id';
+
+  @override
+  void debugFillProperties(DiagnosticPropertiesBuilder properties) {
+    bool hideOwner = true;
+    if (_dirty) {
+      final bool inDirtyNodes = owner != null && owner._dirtyNodes.contains(this);
+      properties.add(new FlagProperty('inDirtyNodes', value: inDirtyNodes, ifTrue: 'dirty', ifFalse: 'STALE'));
+      hideOwner = inDirtyNodes;
+    }
+    properties.add(new DiagnosticsProperty<SemanticsOwner>('owner', owner, hidden: hideOwner));
+    properties.add(new FlagProperty('shouldMergeAllDescendantsIntoThisNode', value: _shouldMergeAllDescendantsIntoThisNode, ifTrue: 'leaf merge'));
     final Offset offset = transform != null ? MatrixUtils.getAsTranslation(transform) : null;
     if (offset != null) {
-      buffer.write('; ${rect.shift(offset)}');
+      properties.add(new DiagnosticsProperty<Rect>('rect', rect.shift(offset), showName: false));
     } else {
       final double scale = transform != null ? MatrixUtils.getAsScale(transform) : null;
+      String description;
       if (scale != null) {
-        buffer.write('; $rect scaled by ${scale.toStringAsFixed(1)}x');
+        description = '$rect scaled by ${scale.toStringAsFixed(1)}x';
       } else if (transform != null && !MatrixUtils.isIdentity(transform)) {
         final String matrix = transform.toString().split('\n').take(4).map((String line) => line.substring(4)).join('; ');
-        buffer.write('; $rect with transform [$matrix]');
-      } else {
-        buffer.write('; $rect');
+        description = '$rect with transform [$matrix]';
       }
+      properties.add(new DiagnosticsProperty<Rect>('rect', rect, description: description, showName: false));
     }
-    if (wasAffectedByClip)
-      buffer.write(' (clipped)');
+    properties.add(new FlagProperty('wasAffectedByClip', value: wasAffectedByClip, ifTrue: 'clipped'));
+    final List<String> actions = <String>[];
     for (SemanticsAction action in SemanticsAction.values.values) {
       if ((_actions & action.index) != 0)
-        buffer.write('; $action');
-    }
-    for (SemanticsTag tag in _tags)
-      buffer.write('; $tag');
-    if (hasCheckedState) {
-      if (isChecked)
-        buffer.write('; checked');
-      else
-        buffer.write('; unchecked');
-    }
-    if (isSelected)
-      buffer.write('; selected');
-    if (label.isNotEmpty)
-      buffer.write('; "$label"');
-    if (textDirection != null)
-      buffer.write('; $textDirection');
-    buffer.write(')');
-    return buffer.toString();
+        actions.add(describeEnum(action));
+    }
+    properties.add(new IterableProperty<String>('actions', actions, hidden: actions.isEmpty));
+    properties.add(new IterableProperty<SemanticsTag>('tags', _tags, hidden: _tags.isEmpty));
+    if (hasCheckedState)
+      properties.add(new FlagProperty('isChecked', value: isChecked, ifTrue: 'checked', ifFalse: 'unchecked'));
+    properties.add(new FlagProperty('isSelected', value: isSelected, ifTrue: 'selected'));
+    properties.add(new StringProperty('label', label, defaultValue: ''));
+    properties.add(new EnumProperty<TextDirection>('textDirection', textDirection, defaultValue: null));
   }
 
   /// Returns a string representation of this node and its descendants.
   ///
   /// The order in which the children of the [SemanticsNode] will be printed is
   /// controlled by the [childOrder] parameter.
-  String toStringDeep(DebugSemanticsDumpOrder childOrder, [
-    String prefixLineOne = '',
-    String prefixOtherLines = ''
-  ]) {
+  @override
+  String toStringDeep({
+    String prefixLineOne: '',
+    String prefixOtherLines,
+    DebugSemanticsDumpOrder childOrder: DebugSemanticsDumpOrder.traversal,
+  }) {
     assert(childOrder != null);
-    final StringBuffer result = new StringBuffer()
-      ..write(prefixLineOne)
-      ..write(this)
-      ..write('\n');
-    if (_children != null && _children.isNotEmpty) {
-      final List<SemanticsNode> childrenInOrder = _getChildrenInOrder(childOrder);
-      for (int index = 0; index < childrenInOrder.length - 1; index += 1) {
-        final SemanticsNode child = childrenInOrder[index];
-        result.write(child.toStringDeep(childOrder, "$prefixOtherLines \u251C", "$prefixOtherLines \u2502"));
-      }
-      result.write(childrenInOrder.last.toStringDeep(childOrder, "$prefixOtherLines \u2514", "$prefixOtherLines  "));
-    }
-    return result.toString();
+    return toDiagnosticsNode(childOrder: childOrder).toStringDeep(prefixLineOne: prefixLineOne, prefixOtherLines: prefixOtherLines);
+  }
+
+  @override
+  DiagnosticsNode toDiagnosticsNode({
+    String name,
+    DiagnosticsTreeStyle style: DiagnosticsTreeStyle.dense,
+    DebugSemanticsDumpOrder childOrder: DebugSemanticsDumpOrder.traversal,
+  }) {
+    return new _SemanticsDiagnosticableNode(
+      name: name,
+      value: this,
+      style: style,
+      childOrder: childOrder,
+    );
+  }
+
+  @override
+  List<DiagnosticsNode> debugDescribeChildren({ DebugSemanticsDumpOrder childOrder: DebugSemanticsDumpOrder.inverseHitTest }) {
+    return _getChildrenInOrder(childOrder)
+      .map<DiagnosticsNode>((SemanticsNode node) => node.toDiagnosticsNode(childOrder: childOrder))
+      .toList();
   }
 
   Iterable<SemanticsNode> _getChildrenInOrder(DebugSemanticsDumpOrder childOrder) {
     assert(childOrder != null);
+    if (_children == null)
+      return const <SemanticsNode>[];
+
     switch(childOrder) {
       case DebugSemanticsDumpOrder.traversal:
         return new List<SemanticsNode>.from(_children)..sort(_geometryComparator);

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

@@ -456,6 +456,6 @@ class FocusManager {
     final String indent = '  ';
     return '${describeIdentity(this)}$status\n'
       '${indent}currentFocus: $_currentFocus\n'
-      '${rootScope.toStringDeep(indent, indent)}';
+      '${rootScope.toStringDeep(prefixLineOne: indent, prefixOtherLines: indent)}';
   }
 }

packages/flutter/test/rendering/semantics_test.dart

@@ -4,6 +4,7 @@
 
 import 'package:flutter/rendering.dart';
 import 'package:test/test.dart';
+import 'package:vector_math/vector_math_64.dart';
 
 import 'rendering_tester.dart';
 
@@ -94,8 +95,8 @@ void main() {
   });
 
   test('toStringDeep() does not throw with transform == null', () {
-    final SemanticsNode child2 = new SemanticsNode();
     final SemanticsNode child1 = new SemanticsNode();
+    final SemanticsNode child2 = new SemanticsNode();
     final SemanticsNode root = new SemanticsNode();
     root.addChildren(<SemanticsNode>[child1, child2]);
     root.finalizeChildren();
@@ -104,10 +105,106 @@ void main() {
     expect(child1.transform, isNull);
     expect(child2.transform, isNull);
 
-    expect(root.toStringDeep(DebugSemanticsDumpOrder.traversal),
-        'SemanticsNode(8 (STALE; owner=null); Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
-        ' ├SemanticsNode(7; Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
-        ' └SemanticsNode(6; Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+    expect(
+      root.toStringDeep(childOrder: DebugSemanticsDumpOrder.traversal),
+      'SemanticsNode#8(STALE, owner: null, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      '├SemanticsNode#6(Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      '└SemanticsNode#7(Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n',
+    );
+  });
+
+  test('toStringDeep respects childOrder parameter', () {
+    final SemanticsNode child1 = new SemanticsNode()
+      ..rect = new Rect.fromLTRB(20.0, 20.0, 20.0, 20.0);
+    final SemanticsNode child2 = new SemanticsNode()
+      ..rect = new Rect.fromLTRB(10.0, 10.0, 10.0, 10.0);
+    final SemanticsNode root = new SemanticsNode();
+    root.addChildren(<SemanticsNode>[child1, child2]);
+    root.finalizeChildren();
+    expect(
+      root.toStringDeep(childOrder: DebugSemanticsDumpOrder.traversal),
+      'SemanticsNode#11(STALE, owner: null, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      '├SemanticsNode#10(STALE, owner: null, Rect.fromLTRB(10.0, 10.0, 10.0, 10.0))\n'
+      '└SemanticsNode#9(STALE, owner: null, Rect.fromLTRB(20.0, 20.0, 20.0, 20.0))\n',
+    );
+
+    expect(
+      root.toStringDeep(childOrder: DebugSemanticsDumpOrder.inverseHitTest),
+      'SemanticsNode#11(STALE, owner: null, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      '├SemanticsNode#9(STALE, owner: null, Rect.fromLTRB(20.0, 20.0, 20.0, 20.0))\n'
+      '└SemanticsNode#10(STALE, owner: null, Rect.fromLTRB(10.0, 10.0, 10.0, 10.0))\n',
+    );
+
+    final SemanticsNode child3 = new SemanticsNode()
+      ..rect = new Rect.fromLTRB(0.0, 0.0, 0.0, 0.0);
+    child3.addChildren(<SemanticsNode>[
+      new SemanticsNode()..rect = new Rect.fromLTRB(20.0, 0.0, 20.0, 0.0),
+      new SemanticsNode(),
+    ]);
+    child3.finalizeChildren();
+
+    final SemanticsNode rootComplex = new SemanticsNode();
+    rootComplex.addChildren(<SemanticsNode>[child1, child2, child3]);
+    rootComplex.finalizeChildren();
+
+    expect(
+      rootComplex.toStringDeep(childOrder: DebugSemanticsDumpOrder.traversal),
+      'SemanticsNode#15(STALE, owner: null, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      '├SemanticsNode#12(STALE, owner: null, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      '│├SemanticsNode#14(Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      '│└SemanticsNode#13(STALE, owner: null, Rect.fromLTRB(20.0, 0.0, 20.0, 0.0))\n'
+      '├SemanticsNode#10(STALE, owner: null, Rect.fromLTRB(10.0, 10.0, 10.0, 10.0))\n'
+      '└SemanticsNode#9(STALE, owner: null, Rect.fromLTRB(20.0, 20.0, 20.0, 20.0))\n',
+    );
+
+    expect(
+      rootComplex.toStringDeep(childOrder: DebugSemanticsDumpOrder.inverseHitTest),
+      'SemanticsNode#15(STALE, owner: null, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      '├SemanticsNode#9(STALE, owner: null, Rect.fromLTRB(20.0, 20.0, 20.0, 20.0))\n'
+      '├SemanticsNode#10(STALE, owner: null, Rect.fromLTRB(10.0, 10.0, 10.0, 10.0))\n'
+      '└SemanticsNode#12(STALE, owner: null, Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n'
+      ' ├SemanticsNode#13(STALE, owner: null, Rect.fromLTRB(20.0, 0.0, 20.0, 0.0))\n'
+      ' └SemanticsNode#14(Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n',
+    );
+  });
+
+  test('debug properties', () {
+    expect(
+      new SemanticsNode().toStringDeep(),
+      'SemanticsNode#16(Rect.fromLTRB(0.0, 0.0, 0.0, 0.0))\n',
+    );
+
+    final SemanticsNode allProperties = new SemanticsNode()
+      ..rect = new Rect.fromLTWH(50.0, 10.0, 20.0, 30.0)
+      ..mergeAllDescendantsIntoThisNode = true
+      ..transform = new Matrix4.translation(new Vector3(10.0, 10.0, 0.0))
+      ..wasAffectedByClip = true
+      ..addAction(SemanticsAction.scrollUp)
+      ..addAction(SemanticsAction.longPress)
+      ..addAction(SemanticsAction.showOnScreen)
+      ..isChecked = false
+      ..isSelected = true
+      ..label = "Use all the properties"
+      ..textDirection = TextDirection.rtl;
+    expect(
+      allProperties.toStringDeep(),
+      'SemanticsNode#17(STALE, owner: null, leaf merge, Rect.fromLTRB(60.0, 20.0, 80.0, 50.0), clipped, actions: [longPress, scrollUp, showOnScreen], selected, label: "Use all the properties", textDirection: rtl)\n',
+    );
+    expect(
+      allProperties.getSemanticsData().toString(),
+      'SemanticsData(Rect.fromLTRB(50.0, 10.0, 70.0, 40.0), [1.0,0.0,0.0,10.0; 0.0,1.0,0.0,10.0; 0.0,0.0,1.0,0.0; 0.0,0.0,0.0,1.0], actions: [longPress, scrollUp, showOnScreen], flags: [isSelected], label: "Use all the properties", textDirection: rtl)',
+    );
+
+    final SemanticsNode scaled = new SemanticsNode()
+      ..rect = new Rect.fromLTWH(50.0, 10.0, 20.0, 30.0)
+      ..transform = new Matrix4.diagonal3(new Vector3(10.0, 10.0, 1.0));
+    expect(
+      scaled.toStringDeep(),
+      'SemanticsNode#18(STALE, owner: null, Rect.fromLTRB(50.0, 10.0, 70.0, 40.0) scaled by 10.0x)\n',
+    );
+    expect(
+      scaled.getSemanticsData().toString(),
+      'SemanticsData(Rect.fromLTRB(50.0, 10.0, 70.0, 40.0), [10.0,0.0,0.0,0.0; 0.0,10.0,0.0,0.0; 0.0,0.0,1.0,0.0; 0.0,0.0,0.0,1.0])',
     );
   });
 

packages/flutter_test/lib/src/matchers.dart

@@ -507,7 +507,7 @@ class _HasGoodToStringDeep extends Matcher {
     final String prefixOtherLines = 'PREFIX_OTHER_LINES_';
     final List<String> prefixIssues = <String>[];
     String descriptionWithPrefixes =
-        object.toStringDeep(prefixLineOne, prefixOtherLines);
+        object.toStringDeep(prefixLineOne: prefixLineOne, prefixOtherLines: prefixOtherLines);
     if (descriptionWithPrefixes.endsWith('\n')) {
       // Trim off trailing \n as the remaining calculations assume
       // the description does not end with a trailing \n.
@@ -532,7 +532,7 @@ class _HasGoodToStringDeep extends Matcher {
 
     if (prefixIssues.isNotEmpty) {
       errorDescription.writeln(
-          'Bad toStringDeep("$prefixLineOne", "$prefixOtherLines"):');
+          'Bad toStringDeep(prefixLineOne: "$prefixLineOne", prefixOtherLines: "$prefixOtherLines"):');
       errorDescription.writeln(descriptionWithPrefixes);
       errorDescription.writeAll(prefixIssues, '\n');
     }

packages/flutter_test/test/matchers_test.dart

@@ -26,7 +26,7 @@ class _MockToStringDeep {
   /// line break.
   List<String> _lines;
 
-  String toStringDeep([String prefixLineOne="", String prefixOtherLines=""]) {
+  String toStringDeep({ String prefixLineOne: "", String prefixOtherLines: "" }) {
     final StringBuffer sb = new StringBuffer();
     if (_lines.isNotEmpty)
       sb.write('$prefixLineOne${_lines.first}');