Reland `find.textRange.ofSubstring` changes (#140469)

Extracted from https://github.com/flutter/flutter/pull/139717 as-is. Landing this change first so we can avoid doing a g3fix.

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

@@ -6,6 +6,7 @@ import 'dart:math' show max, min;
 import 'dart:ui' as ui show
   BoxHeightStyle,
   BoxWidthStyle,
+  GlyphInfo,
   LineMetrics,
   Paragraph,
   ParagraphBuilder,
@@ -24,6 +25,7 @@ import 'strut_style.dart';
 import 'text_scaler.dart';
 import 'text_span.dart';
 
+export 'dart:ui' show LineMetrics;
 export 'package:flutter/services.dart' show TextRange, TextSelection;
 
 /// The default font size if none is specified.
@@ -1493,7 +1495,24 @@ class TextPainter {
       : boxes.map((TextBox box) => _shiftTextBox(box, offset)).toList(growable: false);
   }
 
-  /// Returns the position within the text for the given pixel offset.
+  /// Returns the [GlyphInfo] of the glyph closest to the given `offset` in the
+  /// paragraph coordinate system, or null if the text is empty, or is entirely
+  /// clipped or ellipsized away.
+  ///
+  /// This method first finds the line closest to `offset.dy`, and then returns
+  /// the [GlyphInfo] of the closest glyph(s) within that line.
+   ui.GlyphInfo? getClosestGlyphForOffset(Offset offset) {
+    assert(_debugAssertTextLayoutIsValid);
+    assert(!_debugNeedsRelayout);
+    final _TextPainterLayoutCacheWithOffset cachedLayout = _layoutCache!;
+    final ui.GlyphInfo? rawGlyphInfo = cachedLayout.paragraph.getClosestGlyphInfoForOffset(offset - cachedLayout.paintOffset);
+    if (rawGlyphInfo == null || cachedLayout.paintOffset == Offset.zero) {
+      return rawGlyphInfo;
+    }
+    return ui.GlyphInfo(rawGlyphInfo.graphemeClusterLayoutBounds.shift(cachedLayout.paintOffset), rawGlyphInfo.graphemeClusterCodeUnitRange, rawGlyphInfo.writingDirection);
+  }
+
+  /// Returns the closest position within the text for the given pixel offset.
   TextPosition getPositionForOffset(Offset offset) {
     assert(_debugAssertTextLayoutIsValid);
     assert(!_debugNeedsRelayout);

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

@@ -343,18 +343,20 @@ class TextSpan extends InlineSpan implements HitTestTarget, MouseTrackerAnnotati
   /// Returns the text span that contains the given position in the text.
   @override
   InlineSpan? getSpanForPositionVisitor(TextPosition position, Accumulator offset) {
-    if (text == null) {
+    final String? text = this.text;
+    if (text == null || text.isEmpty) {
       return null;
     }
     final TextAffinity affinity = position.affinity;
     final int targetOffset = position.offset;
-    final int endOffset = offset.value + text!.length;
+    final int endOffset = offset.value + text.length;
+
     if (offset.value == targetOffset && affinity == TextAffinity.downstream ||
         offset.value < targetOffset && targetOffset < endOffset ||
         endOffset == targetOffset && affinity == TextAffinity.upstream) {
       return this;
     }
-    offset.increment(text!.length);
+    offset.increment(text.length);
     return null;
   }
 

packages/flutter/test/painting/text_span_test.dart

@@ -250,6 +250,24 @@ void main() {
     expect(textSpan2.compareTo(textSpan2), RenderComparison.identical);
   });
 
+  test('GetSpanForPosition', () {
+    const TextSpan textSpan = TextSpan(
+      text: '',
+      children: <InlineSpan>[
+        TextSpan(text: '', children: <InlineSpan>[
+          TextSpan(text: 'a'),
+        ]),
+        TextSpan(text: 'b'),
+        TextSpan(text: 'c'),
+      ],
+    );
+
+    expect((textSpan.getSpanForPosition(const TextPosition(offset: 0)) as TextSpan?)?.text, 'a');
+    expect((textSpan.getSpanForPosition(const TextPosition(offset: 1)) as TextSpan?)?.text, 'b');
+    expect((textSpan.getSpanForPosition(const TextPosition(offset: 2)) as TextSpan?)?.text, 'c');
+    expect((textSpan.getSpanForPosition(const TextPosition(offset: 3)) as TextSpan?)?.text, isNull);
+  });
+
   test('GetSpanForPosition with WidgetSpan', () {
     const TextSpan textSpan = TextSpan(
       text: 'a',

packages/flutter_test/lib/src/controller.dart

@@ -24,6 +24,23 @@ const double kDragSlopDefault = 20.0;
 
 const String _defaultPlatform = kIsWeb ? 'web' : 'android';
 
+// Finds the end index (exclusive) of the span at `startIndex`, or `endIndex` if
+// there are no other spans between `startIndex` and `endIndex`.
+// The InlineSpan protocol doesn't expose the length of the span so we'll
+// have to iterate through the whole range.
+(InlineSpan, int)? _findEndOfSpan(InlineSpan rootSpan, int startIndex, int endIndex) {
+  assert(endIndex > startIndex);
+  final InlineSpan? subspan = rootSpan.getSpanForPosition(TextPosition(offset: startIndex));
+  if (subspan == null) {
+    return null;
+  }
+  int i = startIndex + 1;
+  while (i < endIndex && rootSpan.getSpanForPosition(TextPosition(offset: i)) == subspan) {
+    i += 1;
+  }
+  return (subspan, i);
+}
+
 // Examples can assume:
 // typedef MyWidget = Placeholder;
 
@@ -997,6 +1014,47 @@ abstract class WidgetController {
     return tapAt(getCenter(finder, warnIfMissed: warnIfMissed, callee: 'tap'), pointer: pointer, buttons: buttons, kind: kind);
   }
 
+  /// Dispatch a pointer down / pointer up sequence at a hit-testable
+  /// [InlineSpan] (typically a [TextSpan]) within the given text range.
+  ///
+  /// This method performs a more spatially precise tap action on a piece of
+  /// static text, than the widget-based [tap] method.
+  ///
+  /// The given [Finder] must find one and only one matching substring, and the
+  /// substring must be hit-testable (meaning, it must not be off-screen, or be
+  /// obscured by other widgets, or in a disabled widget). Otherwise this method
+  /// throws a [FlutterError].
+  ///
+  /// If the target substring contains more than one hit-testable [InlineSpan]s,
+  /// [tapOnText] taps on one of them, but does not guarantee which.
+  ///
+  /// The `pointer` and `button` arguments specify [PointerEvent.pointer] and
+  /// [PointerEvent.buttons] of the tap event.
+  Future<void> tapOnText(finders.FinderBase<finders.TextRangeContext> textRangeFinder, {int? pointer, int buttons = kPrimaryButton }) {
+    final Iterable<finders.TextRangeContext> ranges = textRangeFinder.evaluate();
+    if (ranges.isEmpty) {
+      throw FlutterError(textRangeFinder.toString());
+    }
+    if (ranges.length > 1) {
+      throw FlutterError(
+        '$textRangeFinder. The "tapOnText" method needs a single non-empty TextRange.',
+      );
+    }
+    final Offset? tapLocation = _findHitTestableOffsetIn(ranges.single);
+    if (tapLocation == null) {
+      final finders.TextRangeContext found = textRangeFinder.evaluate().single;
+      throw FlutterError.fromParts(<DiagnosticsNode>[
+          ErrorSummary('Finder specifies a TextRange that can not receive pointer events.'),
+          ErrorDescription('The finder used was: ${textRangeFinder.toString(describeSelf: true)}'),
+          ErrorDescription('Found a matching substring in a static text widget, within ${found.textRange}.'),
+          ErrorDescription('But the "tapOnText" method could not find a hit-testable Offset with in that text range.'),
+          found.renderObject.toDiagnosticsNode(name: 'The RenderBox of that static text widget was', style: DiagnosticsTreeStyle.shallow),
+        ]
+      );
+    }
+    return tapAt(tapLocation, pointer: pointer, buttons: buttons);
+  }
+
   /// Dispatch a pointer down / pointer up sequence at the given location.
   Future<void> tapAt(
     Offset location, {
@@ -1762,6 +1820,45 @@ abstract class WidgetController {
   /// in the documentation for the [flutter_test] library.
   static bool hitTestWarningShouldBeFatal = false;
 
+  /// Finds one hit-testable Offset in the given `textRangeContext`'s render
+  /// object.
+  Offset? _findHitTestableOffsetIn(finders.TextRangeContext textRangeContext) {
+    TestAsyncUtils.guardSync();
+    final TextRange range = textRangeContext.textRange;
+    assert(range.isNormalized);
+    assert(range.isValid);
+    final Offset renderParagraphPaintOffset = textRangeContext.renderObject.localToGlobal(Offset.zero);
+    assert(renderParagraphPaintOffset.isFinite);
+
+    int spanStart = range.start;
+    while (spanStart < range.end) {
+      switch (_findEndOfSpan(textRangeContext.renderObject.text, spanStart, range.end)) {
+        case (final HitTestTarget target, final int endIndex):
+          // Uses BoxHeightStyle.tight in getBoxesForSelection to make sure the
+          // returned boxes don't extend outside of the hit-testable region.
+          final Iterable<Offset> testOffsets = textRangeContext.renderObject
+            .getBoxesForSelection(TextSelection(baseOffset: spanStart, extentOffset: endIndex))
+            // Try hit-testing the center of each TextBox.
+            .map((TextBox textBox) => textBox.toRect().center);
+
+          for (final Offset localOffset in testOffsets) {
+            final HitTestResult result = HitTestResult();
+            final Offset globalOffset = localOffset + renderParagraphPaintOffset;
+            binding.hitTestInView(result, globalOffset, textRangeContext.view.view.viewId);
+            if (result.path.any((HitTestEntry entry) => entry.target == target)) {
+              return globalOffset;
+            }
+          }
+          spanStart = endIndex;
+        case (_, final int endIndex):
+          spanStart = endIndex;
+        case null:
+          break;
+      }
+    }
+    return null;
+  }
+
   Offset _getElementPoint(finders.FinderBase<Element> finder, Offset Function(Size size) sizeToPoint, { required bool warnIfMissed, required String callee }) {
     TestAsyncUtils.guardSync();
     final Iterable<Element> elements = finder.evaluate();
@@ -1791,17 +1888,10 @@ abstract class WidgetController {
       final FlutterView view = _viewOf(finder);
       final HitTestResult result = HitTestResult();
       binding.hitTestInView(result, location, view.viewId);
-      bool found = false;
-      for (final HitTestEntry entry in result.path) {
-        if (entry.target == box) {
-          found = true;
-          break;
-        }
-      }
+      final bool found = result.path.any((HitTestEntry entry) => entry.target == box);
       if (!found) {
         final RenderView renderView = binding.renderViews.firstWhere((RenderView r) => r.flutterView == view);
-        bool outOfBounds = false;
-        outOfBounds = !(Offset.zero & renderView.size).contains(location);
+        final bool outOfBounds = !(Offset.zero & renderView.size).contains(location);
         if (hitTestWarningShouldBeFatal) {
           throw FlutterError.fromParts(<DiagnosticsNode>[
             ErrorSummary('Finder specifies a widget that would not receive pointer events.'),

packages/flutter_test/lib/src/finders.dart

@@ -23,6 +23,26 @@ typedef SemanticsNodePredicate = bool Function(SemanticsNode node);
 /// Signature for [FinderBase.describeMatch].
 typedef DescribeMatchCallback = String Function(Plurality plurality);
 
+/// The `CandidateType` of finders that search for and filter subtrings,
+/// within static text rendered by [RenderParagraph]s.
+final class TextRangeContext {
+  const TextRangeContext._(this.view, this.renderObject, this.textRange);
+
+  /// The [View] containing the static text.
+  ///
+  /// This is used for hit-testing.
+  final View view;
+
+  /// The RenderObject that contains the static text.
+  final RenderParagraph renderObject;
+
+  /// The [TextRange] of the subtring within [renderObject]'s text.
+  final TextRange textRange;
+
+  @override
+  String toString() => 'TextRangeContext($view, $renderObject, $textRange)';
+}
+
 /// Some frequently used [Finder]s and [SemanticsFinder]s.
 const CommonFinders find = CommonFinders._();
 
@@ -42,6 +62,9 @@ class CommonFinders {
   /// Some frequently used semantics finders.
   CommonSemanticsFinders get semantics => const CommonSemanticsFinders._();
 
+  /// Some frequently used text range finders.
+  CommonTextRangeFinders get textRange => const CommonTextRangeFinders._();
+
   /// Finds [Text], [EditableText], and optionally [RichText] widgets
   /// containing string equal to the `text` argument.
   ///
@@ -677,6 +700,35 @@ class CommonSemanticsFinders {
   }
 }
 
+/// Provides lightweight syntax for getting frequently used text range finders.
+///
+/// This class is instantiated once, as [CommonFinders.textRange], under [find].
+final class CommonTextRangeFinders {
+  const CommonTextRangeFinders._();
+
+  /// Finds all non-overlapping occurrences of the given `substring` in the
+  /// static text widgets and returns the [TextRange]s.
+  ///
+  /// If the `skipOffstage` argument is true (the default), then this skips
+  /// static text inside widgets that are [Offstage], or that are from inactive
+  /// [Route]s.
+  ///
+  /// If the `descendentOf` argument is non-null, this method only searches in
+  /// the descendants of that parameter for the given substring.
+  ///
+  /// This finder uses the [Pattern.allMatches] method to match the substring in
+  /// the text. After finding a matching substring in the text, the method
+  /// continues the search from the end of the match, thus skipping overlapping
+  /// occurrences of the substring.
+  FinderBase<TextRangeContext> ofSubstring(String substring, { bool skipOffstage = true, FinderBase<Element>? descendentOf }) {
+    final _TextContainingWidgetFinder textWidgetFinder = _TextContainingWidgetFinder(substring, skipOffstage: skipOffstage, findRichText: true);
+    final Finder elementFinder = descendentOf == null
+      ? textWidgetFinder
+      : _DescendantWidgetFinder(descendentOf, textWidgetFinder, matchRoot: true, skipOffstage: skipOffstage);
+    return _StaticTextRangeFinder(elementFinder, substring);
+  }
+}
+
 /// Describes how a string of text should be pluralized.
 enum Plurality {
   /// Text should be pluralized to describe zero items.
@@ -998,7 +1050,7 @@ abstract class Finder extends FinderBase<Element> with _LegacyFinderMixin {
   @override
   String describeMatch(Plurality plurality) {
     return switch (plurality) {
-      Plurality.zero ||Plurality.many => 'widgets with $description',
+      Plurality.zero || Plurality.many => 'widgets with $description',
       Plurality.one => 'widget with $description',
     };
   }
@@ -1026,6 +1078,61 @@ abstract class SemanticsFinder extends FinderBase<SemanticsNode> {
   }
 }
 
+/// A base class for creating finders that search for static text rendered by a
+/// [RenderParagraph].
+class _StaticTextRangeFinder extends FinderBase<TextRangeContext> {
+  /// Creates a new [_StaticTextRangeFinder] that searches for the given
+  /// `pattern` in the [Element]s found by `_parent`.
+  _StaticTextRangeFinder(this._parent, this.pattern);
+
+  final FinderBase<Element> _parent;
+  final Pattern pattern;
+
+  Iterable<TextRangeContext> _flatMap(Element from) {
+    final RenderObject? renderObject = from.renderObject;
+    // This is currently only exposed on text matchers. Only consider RenderBoxes.
+    if (renderObject is! RenderBox) {
+      return const Iterable<TextRangeContext>.empty();
+    }
+
+    final View view = from.findAncestorWidgetOfExactType<View>()!;
+    final List<RenderParagraph> paragraphs = <RenderParagraph>[];
+
+    void visitor(RenderObject child) {
+      switch (child) {
+        case RenderParagraph():
+          paragraphs.add(child);
+          // No need to continue, we are piggybacking off of a text matcher, so
+          // inline text widgets will be reported separately.
+        case RenderBox():
+          child.visitChildren(visitor);
+        case _:
+      }
+    }
+    visitor(renderObject);
+    Iterable<TextRangeContext> searchInParagraph(RenderParagraph paragraph) {
+      final String text = paragraph.text.toPlainText(includeSemanticsLabels: false);
+      return pattern.allMatches(text)
+        .map((Match match) => TextRangeContext._(view, paragraph, TextRange(start: match.start, end: match.end)));
+    }
+    return paragraphs.expand(searchInParagraph);
+  }
+
+  @override
+  Iterable<TextRangeContext> findInCandidates(Iterable<TextRangeContext> candidates) => candidates;
+
+  @override
+  Iterable<TextRangeContext> get allCandidates => _parent.evaluate().expand(_flatMap);
+
+  @override
+  String describeMatch(Plurality plurality) {
+    return switch (plurality) {
+      Plurality.zero || Plurality.many => 'non-overlapping TextRanges that match the Pattern "$pattern"',
+      Plurality.one => 'non-overlapping TextRange that matches the Pattern "$pattern"',
+    };
+  }
+}
+
 /// A mixin that applies additional filtering to the results of a parent [Finder].
  mixin ChainedFinderMixin<CandidateType> on FinderBase<CandidateType> {
 

packages/flutter_test/test/controller_test.dart

@@ -1482,6 +1482,172 @@ void main() {
       });
     });
   });
+
+  group('WidgetTester.tapOnText', () {
+    final List<String > tapLogs = <String>[];
+    final TapGestureRecognizer tapA = TapGestureRecognizer()..onTap = () { tapLogs.add('A'); };
+    final TapGestureRecognizer tapB = TapGestureRecognizer()..onTap = () { tapLogs.add('B'); };
+    final TapGestureRecognizer tapC = TapGestureRecognizer()..onTap = () { tapLogs.add('C'); };
+    tearDown(tapLogs.clear);
+    tearDownAll(() {
+      tapA.dispose();
+      tapB.dispose();
+      tapC.dispose();
+    });
+
+    testWidgets('basic test', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: Text.rich(TextSpan(text: 'match', recognizer: tapA)),
+        ),
+      );
+
+      await tester.tapOnText(find.textRange.ofSubstring('match'));
+      expect(tapLogs, <String>['A']);
+    });
+
+    testWidgets('partially obstructed: find a hit-testable Offset', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: Stack(
+            fit: StackFit.expand,
+            children: <Widget>[
+              Positioned(
+                left: 100.0 - 9 * 10.0,  // Only the last character is visible.
+                child: Text.rich(TextSpan(text: 'text match', style: const TextStyle(fontSize: 10), recognizer: tapA)),
+              ),
+              const Positioned(
+                left: 0.0,
+                right: 100.0,
+                child: MetaData(behavior: HitTestBehavior.opaque),
+              ),
+            ],
+          ),
+        ),
+      );
+
+      await expectLater(
+        () => tester.tapOnText(find.textRange.ofSubstring('text match')),
+        returnsNormally,
+      );
+    });
+
+    testWidgets('multiline text partially obstructed: find a hit-testable Offset', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: Stack(
+            fit: StackFit.expand,
+            children: <Widget>[
+              Positioned(
+                width: 100.0,
+                top: 23.0,
+                left: 0.0,
+                child: Text.rich(
+                  TextSpan(
+                    style: const TextStyle(fontSize: 10),
+                    children: <InlineSpan>[
+                      TextSpan(text: 'AAAAAAAAA ', recognizer: tapA),
+                      TextSpan(text: 'BBBBBBBBB ', recognizer: tapB), // The only visible line
+                      TextSpan(text: 'CCCCCCCCC ', recognizer: tapC),
+                    ]
+                  )
+                ),
+              ),
+              const Positioned(
+                top: 23.0, // Some random offset to test the global to local Offset conversion
+                left: 0.0,
+                right: 0.0,
+                height: 10.0,
+                child: MetaData(behavior: HitTestBehavior.opaque, child: SizedBox.expand()),
+              ),
+              const Positioned(
+                top: 43.0,
+                left: 0.0,
+                right: 0.0,
+                height: 10.0,
+                child: MetaData(behavior: HitTestBehavior.opaque, child: SizedBox.expand()),
+              ),
+            ],
+          ),
+        ),
+      );
+
+      await tester.tapOnText(find.textRange.ofSubstring('AAAAAAAAA BBBBBBBBB CCCCCCCCC '));
+      expect(tapLogs, <String>['B']);
+    });
+
+    testWidgets('error message: no matching text', (WidgetTester tester) async {
+      await tester.pumpWidget(const SizedBox());
+      await expectLater(
+        () => tester.tapOnText(find.textRange.ofSubstring('nonexistent')),
+        throwsA(isFlutterError.having(
+          (FlutterError error) => error.message,
+          'message',
+          contains('Found 0 non-overlapping TextRanges that match the Pattern "nonexistent": []'),
+        )),
+      );
+    });
+
+    testWidgets('error message: too many matches', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: Text.rich(
+            TextSpan(
+              text: 'match',
+              recognizer: tapA,
+              children: <InlineSpan>[TextSpan(text: 'another match', recognizer: tapB)],
+            ),
+          ),
+        ),
+      );
+
+      await expectLater(
+        () => tester.tapOnText(find.textRange.ofSubstring('match')),
+        throwsA(isFlutterError.having(
+          (FlutterError error) => error.message,
+          'message',
+          stringContainsInOrder(<String>[
+            'Found 2 non-overlapping TextRanges that match the Pattern "match"',
+            'TextRange(start: 0, end: 5)',
+            'TextRange(start: 13, end: 18)',
+            'The "tapOnText" method needs a single non-empty TextRange.',
+          ])
+        )),
+      );
+    });
+
+    testWidgets('error message: not hit-testable', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        Directionality(
+          textDirection: TextDirection.ltr,
+          child: Stack(
+            fit: StackFit.expand,
+            children: <Widget>[
+              Text.rich(TextSpan(text: 'match', recognizer: tapA)),
+              const MetaData(behavior: HitTestBehavior.opaque),
+            ],
+          ),
+        ),
+      );
+
+      await expectLater(
+        () => tester.tapOnText(find.textRange.ofSubstring('match')),
+        throwsA(isFlutterError.having(
+          (FlutterError error) => error.message,
+          'message',
+          stringContainsInOrder(<String>[
+            'The finder used was: A finder that searches for non-overlapping TextRanges that match the Pattern "match".',
+            'Found a matching substring in a static text widget, within TextRange(start: 0, end: 5).',
+            'But the "tapOnText" method could not find a hit-testable Offset with in that text range.',
+          ])
+        )),
+      );
+    });
+  });
 }
 
 class _SemanticsTestWidget extends StatelessWidget {

packages/flutter_test/test/finders_test.dart

@@ -331,6 +331,100 @@ void main() {
     });
   });
 
+  group('text range finders', () {
+    testWidgets('basic text span test', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        _boilerplate(const IndexedStack(
+          sizing: StackFit.expand,
+          children: <Widget>[
+            Text.rich(TextSpan(
+              text: 'sub',
+              children: <InlineSpan>[
+                TextSpan(text: 'stringsub'),
+                TextSpan(text: 'stringsub'),
+                TextSpan(text: 'stringsub'),
+              ],
+            )),
+            Text('substringsub'),
+          ],
+        )),
+      );
+
+      expect(find.textRange.ofSubstring('substringsub'), findsExactly(2)); // Pattern skips overlapping matches.
+      expect(find.textRange.ofSubstring('substringsub').first.evaluate().single.textRange, const TextRange(start: 0, end: 12));
+      expect(find.textRange.ofSubstring('substringsub').last.evaluate().single.textRange, const TextRange(start: 18, end: 30));
+
+      expect(
+        find.textRange.ofSubstring('substringsub').first.evaluate().single.renderObject,
+        find.textRange.ofSubstring('substringsub').last.evaluate().single.renderObject,
+      );
+
+      expect(find.textRange.ofSubstring('substringsub', skipOffstage: false), findsExactly(3));
+    });
+
+    testWidgets('basic text span test', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        _boilerplate(const IndexedStack(
+          sizing: StackFit.expand,
+          children: <Widget>[
+            Text.rich(TextSpan(
+              text: 'sub',
+              children: <InlineSpan>[
+                TextSpan(text: 'stringsub'),
+                TextSpan(text: 'stringsub'),
+                TextSpan(text: 'stringsub'),
+              ],
+            )),
+            Text('substringsub'),
+          ],
+        )),
+      );
+
+      expect(find.textRange.ofSubstring('substringsub'), findsExactly(2)); // Pattern skips overlapping matches.
+      expect(find.textRange.ofSubstring('substringsub').first.evaluate().single.textRange, const TextRange(start: 0, end: 12));
+      expect(find.textRange.ofSubstring('substringsub').last.evaluate().single.textRange, const TextRange(start: 18, end: 30));
+
+      expect(
+        find.textRange.ofSubstring('substringsub').first.evaluate().single.renderObject,
+        find.textRange.ofSubstring('substringsub').last.evaluate().single.renderObject,
+      );
+
+      expect(find.textRange.ofSubstring('substringsub', skipOffstage: false), findsExactly(3));
+    });
+
+    testWidgets('descendentOf', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        _boilerplate(
+          const Column(
+            children: <Widget>[
+              Text.rich(TextSpan(text: 'text')),
+              Text.rich(TextSpan(text: 'text')),
+            ],
+          ),
+        ),
+      );
+
+      expect(find.textRange.ofSubstring('text'), findsExactly(2));
+      expect(find.textRange.ofSubstring('text', descendentOf: find.text('text').first), findsOne);
+    });
+
+    testWidgets('finds only static text for now', (WidgetTester tester) async {
+      await tester.pumpWidget(
+        _boilerplate(
+          EditableText(
+            controller: TextEditingController(text: 'text'),
+            focusNode: FocusNode(),
+            style: const TextStyle(),
+            cursorColor: const Color(0x00000000),
+            backgroundCursorColor: const Color(0x00000000),
+          )
+        ),
+      );
+
+      expect(find.textRange.ofSubstring('text'), findsNothing);
+    });
+  });
+
   testWidgets('ChainedFinders chain properly', (WidgetTester tester) async {
     final GlobalKey key1 = GlobalKey();
     await tester.pumpWidget(