Makes TextBoundary and its subclasses public (#110367)

packages/flutter/lib/services.dart

@@ -43,6 +43,7 @@ export 'src/services/system_channels.dart';
 export 'src/services/system_chrome.dart';
 export 'src/services/system_navigator.dart';
 export 'src/services/system_sound.dart';
+export 'src/services/text_boundary.dart';
 export 'src/services/text_editing.dart';
 export 'src/services/text_editing_delta.dart';
 export 'src/services/text_formatter.dart';

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

@@ -1129,6 +1129,12 @@ class TextPainter {
   /// {@endtemplate}
   TextRange getWordBoundary(TextPosition position) {
     assert(_debugAssertTextLayoutIsValid);
+    // TODO(chunhtai): remove this workaround once ui.Paragraph.getWordBoundary
+    // can handle caret position.
+    // https://github.com/flutter/flutter/issues/111751.
+    if (position.affinity == TextAffinity.upstream) {
+      position = TextPosition(offset: position.offset - 1);
+    }
     return _paragraph!.getWordBoundary(position);
   }
 

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

@@ -2040,7 +2040,6 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     final TextSelection firstWord = _getWordAtOffset(firstPosition);
     final TextSelection lastWord = to == null ?
       firstWord : _getWordAtOffset(_textPainter.getPositionForOffset(globalToLocal(to - _paintOffset)));
-
     _setSelection(
       TextSelection(
         baseOffset: firstWord.base.offset,
@@ -2071,14 +2070,28 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
 
   TextSelection _getWordAtOffset(TextPosition position) {
     debugAssertLayoutUpToDate();
-    final TextRange word = _textPainter.getWordBoundary(position);
     // When long-pressing past the end of the text, we want a collapsed cursor.
-    if (position.offset >= word.end) {
-      return TextSelection.fromPosition(position);
+    if (position.offset >= _plainText.length) {
+      return TextSelection.fromPosition(
+        TextPosition(offset: _plainText.length, affinity: TextAffinity.upstream)
+      );
     }
     // If text is obscured, the entire sentence should be treated as one word.
     if (obscureText) {
       return TextSelection(baseOffset: 0, extentOffset: _plainText.length);
+    }
+    final TextRange word = _textPainter.getWordBoundary(position);
+    final int effectiveOffset;
+    switch (position.affinity) {
+      case TextAffinity.upstream:
+        // upstream affinity is effectively -1 in text position.
+        effectiveOffset = position.offset - 1;
+        break;
+      case TextAffinity.downstream:
+        effectiveOffset = position.offset;
+        break;
+    }
+
     // On iOS, select the previous word if there is a previous word, or select
     // to the end of the next word if there is a next word. Select nothing if
     // there is neither a previous word nor a next word.
@@ -2086,8 +2099,8 @@ class RenderEditable extends RenderBox with RelayoutWhenSystemFontsChangeMixin,
     // If the platform is Android and the text is read only, try to select the
     // previous word if there is one; otherwise, select the single whitespace at
     // the position.
-    } else if (TextLayoutMetrics.isWhitespace(_plainText.codeUnitAt(position.offset))
-        && position.offset > 0) {
+    if (TextLayoutMetrics.isWhitespace(_plainText.codeUnitAt(effectiveOffset))
+        && effectiveOffset > 0) {
       assert(defaultTargetPlatform != null);
       final TextRange? previousWord = _getPreviousWord(word.start);
       switch (defaultTargetPlatform) {

packages/flutter/lib/src/services/text_boundary.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:math' as math;
+import 'dart:ui';
+
+import 'package:characters/characters.dart' show CharacterRange;
+
+import 'text_layout_metrics.dart';
+
+/// An interface for retrieving the logical text boundary (left-closed-right-open)
+/// at a given location in a document.
+///
+/// The input [TextPosition] points to a position between 2 code units (which
+/// can be visually represented by the caret if the selection were to collapse
+/// to that position). The [TextPosition.affinity] is used to determine which
+/// code unit it points. For example, `TextPosition(i, upstream)` points to
+/// code unit `i - 1` and `TextPosition(i, downstream)` points to code unit `i`.
+abstract class TextBoundary {
+  /// A constant constructor to enable subclass override.
+  const TextBoundary();
+
+  /// Returns the leading text boundary at the given location.
+  ///
+  /// The return value must be less or equal to the input position.
+  TextPosition getLeadingTextBoundaryAt(TextPosition position);
+
+  /// Returns the trailing text boundary at the given location, exclusive.
+  ///
+  /// The return value must be greater or equal to the input position.
+  TextPosition getTrailingTextBoundaryAt(TextPosition position);
+
+  /// Gets the text boundary range that encloses the input position.
+  TextRange getTextBoundaryAt(TextPosition position) {
+    return TextRange(
+      start: getLeadingTextBoundaryAt(position).offset,
+      end: getTrailingTextBoundaryAt(position).offset,
+    );
+  }
+}
+
+/// A text boundary that uses characters as logical boundaries.
+///
+/// This class takes grapheme clusters into account and avoid creating
+/// boundaries that generate malformed utf-16 characters.
+class CharacterBoundary extends TextBoundary {
+  /// Creates a [CharacterBoundary] with the text.
+  const CharacterBoundary(this._text);
+
+  final String _text;
+
+  @override
+  TextPosition getLeadingTextBoundaryAt(TextPosition position) {
+    if (position.offset <= 0) {
+      return const TextPosition(offset: 0);
+    }
+    if (position.offset > _text.length ||
+        (position.offset == _text.length && position.affinity == TextAffinity.downstream)) {
+      return TextPosition(offset: _text.length, affinity: TextAffinity.upstream);
+    }
+    final int endOffset;
+    final int startOffset;
+    switch (position.affinity) {
+      case TextAffinity.upstream:
+        startOffset = math.min(position.offset - 1, _text.length);
+        endOffset = math.min(position.offset, _text.length);
+        break;
+      case TextAffinity.downstream:
+        startOffset = math.min(position.offset, _text.length);
+        endOffset = math.min(position.offset + 1, _text.length);
+        break;
+    }
+    return TextPosition(
+      offset: CharacterRange.at(_text, startOffset, endOffset).stringBeforeLength,
+    );
+  }
+
+  @override
+  TextPosition getTrailingTextBoundaryAt(TextPosition position) {
+    if (position.offset < 0 ||
+        (position.offset == 0 && position.affinity == TextAffinity.upstream)) {
+      return const TextPosition(offset: 0);
+    }
+    if (position.offset >= _text.length) {
+      return TextPosition(offset: _text.length, affinity: TextAffinity.upstream);
+    }
+    final int endOffset;
+    final int startOffset;
+    switch (position.affinity) {
+      case TextAffinity.upstream:
+        startOffset = math.min(position.offset - 1, _text.length);
+        endOffset = math.min(position.offset, _text.length);
+        break;
+      case TextAffinity.downstream:
+        startOffset = math.min(position.offset, _text.length);
+        endOffset = math.min(position.offset + 1, _text.length);
+        break;
+    }
+    final CharacterRange range = CharacterRange.at(_text, startOffset, endOffset);
+    return TextPosition(
+      offset: _text.length - range.stringAfterLength,
+      affinity: TextAffinity.upstream,
+    );
+  }
+}
+
+/// A text boundary that uses words as logical boundaries.
+///
+/// This class uses [UAX #29](https://unicode.org/reports/tr29/) defined word
+/// boundaries to calculate its logical boundaries.
+class WordBoundary extends TextBoundary {
+  /// Creates a [CharacterBoundary] with the text and layout information.
+  const WordBoundary(this._textLayout);
+
+  final TextLayoutMetrics _textLayout;
+
+  @override
+  TextPosition getLeadingTextBoundaryAt(TextPosition position) {
+    return TextPosition(
+      offset: _textLayout.getWordBoundary(position).start,
+      affinity: TextAffinity.downstream,  // ignore: avoid_redundant_argument_values
+    );
+  }
+  @override
+  TextPosition getTrailingTextBoundaryAt(TextPosition position) {
+    return TextPosition(
+      offset: _textLayout.getWordBoundary(position).end,
+      affinity: TextAffinity.upstream,
+    );
+  }
+}
+
+/// A text boundary that uses line breaks as logical boundaries.
+///
+/// The input [TextPosition]s will be interpreted as caret locations if
+/// [TextLayoutMetrics.getLineAtOffset] is text-affinity-aware.
+class LineBreak extends TextBoundary {
+  /// Creates a [CharacterBoundary] with the text and layout information.
+  const LineBreak(this._textLayout);
+
+  final TextLayoutMetrics _textLayout;
+
+  @override
+  TextPosition getLeadingTextBoundaryAt(TextPosition position) {
+    return TextPosition(
+      offset: _textLayout.getLineAtOffset(position).start,
+    );
+  }
+
+  @override
+  TextPosition getTrailingTextBoundaryAt(TextPosition position) {
+    return TextPosition(
+      offset: _textLayout.getLineAtOffset(position).end,
+      affinity: TextAffinity.upstream,
+    );
+  }
+}
+
+/// A text boundary that uses the entire document as logical boundary.
+///
+/// The document boundary is unique and is a constant function of the input
+/// position.
+class DocumentBoundary extends TextBoundary {
+  /// Creates a [CharacterBoundary] with the text
+  const DocumentBoundary(this._text);
+
+  final String _text;
+
+  @override
+  TextPosition getLeadingTextBoundaryAt(TextPosition position) => const TextPosition(offset: 0);
+  @override
+  TextPosition getTrailingTextBoundaryAt(TextPosition position) {
+    return TextPosition(
+      offset: _text.length,
+      affinity: TextAffinity.upstream,
+    );
+  }
+}

packages/flutter/test/cupertino/text_field_test.dart

@@ -199,7 +199,8 @@ void main() {
     return endpoints[0].point;
   }
 
-  Offset textOffsetToPosition(WidgetTester tester, int offset) => textOffsetToBottomLeftPosition(tester, offset) + const Offset(0, -2);
+  // Web has a less threshold for downstream/upstream text position.
+  Offset textOffsetToPosition(WidgetTester tester, int offset) => textOffsetToBottomLeftPosition(tester, offset) + const Offset(kIsWeb ? 1 : 0, -2);
 
   setUp(() async {
     EditableText.debugDeterministicCursor = false;
@@ -2087,6 +2088,7 @@ void main() {
     await tester.pump(const Duration(milliseconds: 50));
     await tester.tapAt(textOffsetToPosition(tester, 5));
     await tester.pumpAndSettle();
+
     expect(controller.value.selection, isNotNull);
     expect(controller.value.selection.baseOffset, 5);
     expect(controller.value.selection.extentOffset, 6);
@@ -3053,7 +3055,7 @@ void main() {
     expect(controller.selection.extentOffset, 8);
 
     // Tiny movement shouldn't cause text selection to change.
-    await gesture.moveTo(gPos + const Offset(4.0, 0.0));
+    await gesture.moveTo(gPos + const Offset(2.0, 0.0));
     await tester.pumpAndSettle();
     expect(selectionChangedCount, 0);
 

packages/flutter/test/material/text_field_test.dart

@@ -2172,7 +2172,7 @@ void main() {
     expect(controller.selection.extentOffset, 8);
 
     // Tiny movement shouldn't cause text selection to change.
-    await gesture.moveTo(gPos + const Offset(4.0, 0.0));
+    await gesture.moveTo(gPos + const Offset(2.0, 0.0));
     await tester.pumpAndSettle();
     expect(selectionChangedCount, 0);
 
@@ -3372,10 +3372,7 @@ void main() {
     final Offset secondPos = textOffsetToPosition(tester, testValue.indexOf('Second'));
     final Offset thirdPos = textOffsetToPosition(tester, testValue.indexOf('Third'));
     final Offset middleStringPos = textOffsetToPosition(tester, testValue.indexOf('irst'));
-    expect(firstPos.dx, 0);
-    expect(secondPos.dx, 0);
-    expect(thirdPos.dx, 0);
-    expect(middleStringPos.dx, 34);
+    expect(firstPos.dx, lessThan(middleStringPos.dx));
     expect(firstPos.dx, secondPos.dx);
     expect(firstPos.dx, thirdPos.dx);
     expect(firstPos.dy, lessThan(secondPos.dy));
@@ -3457,8 +3454,6 @@ void main() {
     // Check that the last line of text is not displayed.
     final Offset firstPos = textOffsetToPosition(tester, kMoreThanFourLines.indexOf('First'));
     final Offset fourthPos = textOffsetToPosition(tester, kMoreThanFourLines.indexOf('Fourth'));
-    expect(firstPos.dx, 0);
-    expect(fourthPos.dx, 0);
     expect(firstPos.dx, fourthPos.dx);
     expect(firstPos.dy, lessThan(fourthPos.dy));
     expect(inputBox.hitTest(BoxHitTestResult(), position: inputBox.globalToLocal(firstPos)), isTrue);
@@ -8397,10 +8392,10 @@ void main() {
         ),
       ),
     );
-
+    final Size screenSize = MediaQuery.of(tester.element(find.byType(TextField))).size;
     // Just testing the test and making sure that the last character is off
     // the right side of the screen.
-    expect(textOffsetToPosition(tester, 66).dx, 1056);
+    expect(textOffsetToPosition(tester, 66).dx, greaterThan(screenSize.width));
 
     final TestGesture gesture =
         await tester.startGesture(
@@ -8448,7 +8443,7 @@ void main() {
     );
 
     // The first character is now offscreen to the left.
-    expect(textOffsetToPosition(tester, 0).dx, moreOrLessEquals(-257.0, epsilon: 1));
+    expect(textOffsetToPosition(tester, 0).dx, lessThan(-100.0));
   }, variant: TargetPlatformVariant.all());
 
   testWidgets('keyboard selection change scrolls the field', (WidgetTester tester) async {
@@ -8485,7 +8480,7 @@ void main() {
     await tester.pumpAndSettle();
     expect(
       controller.selection,
-      const TextSelection.collapsed(offset: 56),
+      const TextSelection.collapsed(offset: 56, affinity: TextAffinity.upstream),
     );
 
     // Keep moving out.
@@ -8495,7 +8490,7 @@ void main() {
     await tester.pumpAndSettle();
     expect(
       controller.selection,
-      const TextSelection.collapsed(offset: 62),
+      const TextSelection.collapsed(offset: 62, affinity: TextAffinity.upstream),
     );
     for (int i = 0; i < (66 - 62); i += 1) {
       await tester.sendKeyEvent(LogicalKeyboardKey.arrowRight);
@@ -8503,7 +8498,7 @@ void main() {
     await tester.pumpAndSettle();
     expect(
       controller.selection,
-      const TextSelection.collapsed(offset: 66),
+      const TextSelection.collapsed(offset: 66, affinity: TextAffinity.upstream),
     ); // We're at the edge now.
 
     await tester.pumpAndSettle();

packages/flutter/test/services/text_boundary_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 'package:flutter/services.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('Character boundary works', () {
+    const CharacterBoundary boundary = CharacterBoundary('abc');
+    const TextPosition midPosition = TextPosition(offset: 1);
+    expect(boundary.getLeadingTextBoundaryAt(midPosition), const TextPosition(offset: 1));
+    expect(boundary.getTrailingTextBoundaryAt(midPosition), const TextPosition(offset: 2, affinity: TextAffinity.upstream));
+
+    const TextPosition startPosition = TextPosition(offset: 0);
+    expect(boundary.getLeadingTextBoundaryAt(startPosition), const TextPosition(offset: 0));
+    expect(boundary.getTrailingTextBoundaryAt(startPosition), const TextPosition(offset: 1, affinity: TextAffinity.upstream));
+
+    const TextPosition endPosition = TextPosition(offset: 3);
+    expect(boundary.getLeadingTextBoundaryAt(endPosition), const TextPosition(offset: 3, affinity: TextAffinity.upstream));
+    expect(boundary.getTrailingTextBoundaryAt(endPosition), const TextPosition(offset: 3, affinity: TextAffinity.upstream));
+  });
+
+  test('Character boundary works with grapheme', () {
+    const String text = 'a❄︎c';
+    const CharacterBoundary boundary = CharacterBoundary(text);
+    TextPosition position = const TextPosition(offset: 1);
+    expect(boundary.getLeadingTextBoundaryAt(position), const TextPosition(offset: 1));
+    // The `❄` takes two character length.
+    expect(boundary.getTrailingTextBoundaryAt(position), const TextPosition(offset: 3, affinity: TextAffinity.upstream));
+
+    position = const TextPosition(offset: 2);
+    expect(boundary.getLeadingTextBoundaryAt(position), const TextPosition(offset: 1));
+    expect(boundary.getTrailingTextBoundaryAt(position), const TextPosition(offset: 3, affinity: TextAffinity.upstream));
+
+    position = const TextPosition(offset: 0);
+    expect(boundary.getLeadingTextBoundaryAt(position), const TextPosition(offset: 0));
+    expect(boundary.getTrailingTextBoundaryAt(position), const TextPosition(offset: 1, affinity: TextAffinity.upstream));
+
+    position = const TextPosition(offset: text.length);
+    expect(boundary.getLeadingTextBoundaryAt(position), const TextPosition(offset: text.length, affinity: TextAffinity.upstream));
+    expect(boundary.getTrailingTextBoundaryAt(position), const TextPosition(offset: text.length, affinity: TextAffinity.upstream));
+  });
+
+  test('word boundary works', () {
+    final WordBoundary boundary = WordBoundary(TestTextLayoutMetrics());
+    const TextPosition position = TextPosition(offset: 3);
+    expect(boundary.getLeadingTextBoundaryAt(position).offset, TestTextLayoutMetrics.wordBoundaryAt3.start);
+    expect(boundary.getTrailingTextBoundaryAt(position).offset, TestTextLayoutMetrics.wordBoundaryAt3.end);
+  });
+
+  test('line boundary works', () {
+    final LineBreak boundary = LineBreak(TestTextLayoutMetrics());
+    const TextPosition position = TextPosition(offset: 3);
+    expect(boundary.getLeadingTextBoundaryAt(position).offset, TestTextLayoutMetrics.lineAt3.start);
+    expect(boundary.getTrailingTextBoundaryAt(position).offset, TestTextLayoutMetrics.lineAt3.end);
+  });
+
+  test('document boundary works', () {
+    const String text = 'abcd efg hi\njklmno\npqrstuv';
+    const DocumentBoundary boundary = DocumentBoundary(text);
+    const TextPosition position = TextPosition(offset: 10);
+    expect(boundary.getLeadingTextBoundaryAt(position), const TextPosition(offset: 0));
+    expect(boundary.getTrailingTextBoundaryAt(position), const TextPosition(offset: text.length, affinity: TextAffinity.upstream));
+  });
+}
+
+class TestTextLayoutMetrics extends TextLayoutMetrics {
+  static const TextSelection lineAt3 = TextSelection(baseOffset: 0, extentOffset: 10);
+  static const TextRange wordBoundaryAt3 = TextRange(start: 4, end: 7);
+
+  @override
+  TextSelection getLineAtOffset(TextPosition position) {
+    if (position.offset == 3) {
+      return lineAt3;
+    }
+    throw UnimplementedError();
+  }
+
+  @override
+  TextPosition getTextPositionAbove(TextPosition position) {
+    throw UnimplementedError();
+  }
+
+  @override
+  TextPosition getTextPositionBelow(TextPosition position) {
+    throw UnimplementedError();
+  }
+
+  @override
+  TextRange getWordBoundary(TextPosition position) {
+    if (position.offset == 3) {
+      return wordBoundaryAt3;
+    }
+    throw UnimplementedError();
+  }
+}

packages/flutter/test/widgets/editable_text_shortcuts_test.dart

@@ -1229,6 +1229,7 @@ void main() {
 
             expect(controller.selection, const TextSelection.collapsed(
               offset: 21,
+              affinity: TextAffinity.upstream,
             ));
           }, variant: TargetPlatformVariant.all());
 
@@ -1243,6 +1244,7 @@ void main() {
 
             expect(controller.selection, const TextSelection.collapsed(
               offset: 10,
+              affinity: TextAffinity.upstream,
             ));
           }, variant: allExceptApple);
 
@@ -1353,6 +1355,7 @@ void main() {
             await tester.pump();
             expect(controller.selection, const TextSelection.collapsed(
               offset: 46, // After "to".
+              affinity: TextAffinity.upstream,
             ));
 
             // "good" to "come" is selected.
@@ -1365,6 +1368,7 @@ void main() {
             await tester.pump();
             expect(controller.selection, const TextSelection.collapsed(
               offset: 28, // After "good".
+              affinity: TextAffinity.upstream,
             ));
           }, variant: allExceptApple);
 
@@ -1673,6 +1677,7 @@ void main() {
 
       expect(controller.selection, const TextSelection.collapsed(
         offset: 10,
+        affinity: TextAffinity.upstream,
       ));
     }, variant: macOSOnly);
 
@@ -1743,6 +1748,7 @@ void main() {
       await tester.pump();
       expect(controller.selection, const TextSelection.collapsed(
         offset: 46, // After "to".
+        affinity: TextAffinity.upstream,
       ));
 
       // "good" to "come" is selected.
@@ -1755,6 +1761,7 @@ void main() {
       await tester.pump();
       expect(controller.selection, const TextSelection.collapsed(
         offset: 28, // After "good".
+        affinity: TextAffinity.upstream,
       ));
     }, variant: macOSOnly);
 

packages/flutter/test/widgets/editable_text_test.dart

@@ -5832,6 +5832,7 @@ void main() {
       equals(
         const TextSelection.collapsed(
           offset: 3,
+          affinity: TextAffinity.upstream,
         ),
       ),
       reason: 'on $platform',
@@ -5941,6 +5942,7 @@ void main() {
         const TextSelection(
           baseOffset: 10,
           extentOffset: 10,
+          affinity: TextAffinity.upstream,
         ),
       ),
       reason: 'on $platform',
@@ -6398,6 +6400,7 @@ void main() {
       equals(
         const TextSelection.collapsed(
           offset: 23,
+          affinity: TextAffinity.upstream,
         ),
       ),
       reason: 'on $platform',
@@ -6422,6 +6425,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 23,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -6464,6 +6468,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 23,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -6549,6 +6554,7 @@ void main() {
       equals(
         const TextSelection.collapsed(
           offset: 32,
+          affinity: TextAffinity.upstream,
         ),
       ),
       reason: 'on $platform',
@@ -6573,6 +6579,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 32,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -6615,6 +6622,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 32,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -6710,6 +6718,7 @@ void main() {
       equals(
         const TextSelection.collapsed(
           offset: 32,
+          affinity: TextAffinity.upstream,
         ),
       ),
       reason: 'on $platform',
@@ -6734,6 +6743,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 32,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -6776,6 +6786,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 32,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -6872,6 +6883,7 @@ void main() {
       equals(
         const TextSelection.collapsed(
           offset: 23,
+          affinity: TextAffinity.upstream,
         ),
       ),
       reason: 'on $platform',
@@ -6917,6 +6929,7 @@ void main() {
             const TextSelection(
               baseOffset: 23,
               extentOffset: 23,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -6927,6 +6940,7 @@ void main() {
             const TextSelection(
               baseOffset: 23,
               extentOffset: 23,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -7060,6 +7074,7 @@ void main() {
       controller.selection,
       equals(const TextSelection.collapsed(
         offset: 4,
+        affinity: TextAffinity.upstream,
       )),
     );
 
@@ -7243,6 +7258,7 @@ void main() {
       equals(
         const TextSelection.collapsed(
           offset: 32,
+          affinity: TextAffinity.upstream,
         ),
       ),
       reason: 'on $platform',
@@ -7266,6 +7282,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 32,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -7323,6 +7340,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 32,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -7435,6 +7453,7 @@ void main() {
       equals(
         const TextSelection.collapsed(
           offset: 32,
+          affinity: TextAffinity.upstream,
         ),
       ),
       reason: 'on $platform',
@@ -7458,6 +7477,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 32,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -7515,6 +7535,7 @@ void main() {
           equals(
             const TextSelection.collapsed(
               offset: 32,
+              affinity: TextAffinity.upstream,
             ),
           ),
           reason: 'on $platform',
@@ -7626,6 +7647,7 @@ void main() {
       equals(
         const TextSelection.collapsed(
           offset: 32,
+          affinity: TextAffinity.upstream,
         ),
       ),
     );
@@ -10383,7 +10405,6 @@ void main() {
     expect(controller.selection.isCollapsed, false);
     expect(controller.selection.baseOffset, 7);
     expect(controller.selection.extentOffset, 10);
-
     await sendKeys(
       tester,
       <LogicalKeyboardKey>[LogicalKeyboardKey.arrowLeft],

packages/flutter/test/widgets/editable_text_utils.dart

@@ -2,6 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/rendering.dart';
 import 'package:flutter_test/flutter_test.dart';
@@ -42,7 +43,7 @@ Offset textOffsetToPosition(WidgetTester tester, int offset) {
     renderEditable,
   );
   expect(endpoints.length, 1);
-  return endpoints[0].point + const Offset(0.0, -2.0);
+  return endpoints[0].point + const Offset(kIsWeb? 1.0 : 0.0, -2.0);
 }
 
 // Simple controller that builds a WidgetSpan with 100 height.