Add 'Share' button to the selection toolbar on Android (#139479)

## Description

This PR adds the 'Share' button to the text selection toolbar on Android.

## Related Issue

Fixes https://github.com/flutter/flutter/issues/138728

## Tests

Refactor a lot of existing tests in order to:
- make them more readable (avoid duplication by introducing helper functions, specify explictly check which buttons are expected).
- make them more accurate (check that expected buttons are visible instead of just checking the number of buttons).

For instance, previous tests contained sections such as:

```dart

      // Collapsed toolbar shows 3 buttons.
      expect(
        find.byType(CupertinoButton),
        isContextMenuProvidedByPlatform ? findsNothing : isTargetPlatformIOS ? findsNWidgets(6) : findsNWidgets(3)
      );

```

Where the comment is obsolete, the two cases (6 widgets and 3 widgets) are not explicit (which buttons are expected?), and not accurate (will pass if the number of buttons is right but the buttons are the wrong ones).

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

@@ -226,7 +226,7 @@ class AdaptiveTextSelectionToolbar extends StatelessWidget {
           case ContextMenuButtonType.searchWeb:
             return localizations.searchWebButtonLabel;
           case ContextMenuButtonType.share:
-            return localizations.searchWebButtonLabel;
+            return localizations.shareButtonLabel;
           case ContextMenuButtonType.liveTextInput:
             return localizations.scanTextButtonLabel;
           case ContextMenuButtonType.custom:

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

@@ -1882,6 +1882,10 @@ class EditableText extends StatefulWidget {
       // If the paste button is enabled, don't render anything until the state
       // of the clipboard is known, since it's used to determine if paste is
       // shown.
+
+      // On Android, the share button is before the select all button.
+      final bool showShareBeforeSelectAll = defaultTargetPlatform == TargetPlatform.android;
+
       resultButtonItem.addAll(<ContextMenuButtonItem>[
         if (onCut != null)
           ContextMenuButtonItem(
@@ -1898,6 +1902,11 @@ class EditableText extends StatefulWidget {
             onPressed: onPaste,
             type: ContextMenuButtonType.paste,
           ),
+        if (onShare != null && showShareBeforeSelectAll)
+          ContextMenuButtonItem(
+            onPressed: onShare,
+            type: ContextMenuButtonType.share,
+          ),
         if (onSelectAll != null)
           ContextMenuButtonItem(
             onPressed: onSelectAll,
@@ -1913,7 +1922,7 @@ class EditableText extends StatefulWidget {
             onPressed: onSearchWeb,
             type: ContextMenuButtonType.searchWeb,
           ),
-        if (onShare != null)
+        if (onShare != null && !showShareBeforeSelectAll)
           ContextMenuButtonItem(
             onPressed: onShare,
             type: ContextMenuButtonType.share,
@@ -2300,13 +2309,18 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
 
   @override
   bool get shareEnabled {
-    if (defaultTargetPlatform != TargetPlatform.iOS) {
-      return false;
-    }
-
+    switch (defaultTargetPlatform) {
+      case TargetPlatform.android:
+      case TargetPlatform.iOS:
         return !widget.obscureText
             && !textEditingValue.selection.isCollapsed
             && textEditingValue.selection.textInside(textEditingValue.text).trim() != '';
+      case TargetPlatform.macOS:
+      case TargetPlatform.fuchsia:
+      case TargetPlatform.linux:
+      case TargetPlatform.windows:
+        return false;
+    }
   }
 
   @override
@@ -2516,9 +2530,9 @@ class EditableTextState extends State<EditableText> with AutomaticKeepAliveClien
   }
 
   /// Launch the share interface for the current selection,
-  /// as in the "Share" edit menu button on iOS.
+  /// as in the "Share..." edit menu button on iOS.
   ///
-  /// Currently this is only implemented for iOS.
+  /// Currently this is only implemented for iOS and Android.
   ///
   /// When 'obscureText' is true or the selection is empty,
   /// this function will not do anything

packages/flutter/test/cupertino/adaptive_text_selection_toolbar_test.dart

@@ -10,6 +10,7 @@ import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 
 import '../widgets/clipboard_utils.dart';
 import '../widgets/live_text_utils.dart';
+import '../widgets/text_selection_toolbar_utils.dart';
 
 void main() {
   final MockClipboard mockClipboard = MockClipboard();
@@ -31,13 +32,6 @@ void main() {
     );
   });
 
-  Finder findOverflowNextButton() {
-    return find.byWidgetPredicate((Widget widget) =>
-      widget is CustomPaint &&
-          '${widget.painter?.runtimeType}' == '_RightCupertinoChevronPainter',
-      );
-  }
-
   testWidgetsWithLeakTracking('Builds the right toolbar on each platform, including web, and shows buttonItems', (WidgetTester tester) async {
     const String buttonText = 'Click me';
 
@@ -188,27 +182,55 @@ void main() {
     ));
 
     expect(find.byKey(key), findsOneWidget);
-    expect(find.text('Copy'), findsOneWidget);
-    expect(find.text('Cut'), findsOneWidget);
-    expect(find.text('Select All'), findsOneWidget);
-    expect(find.text('Paste'), findsOneWidget);
-    expect(find.text('Look Up'), findsOneWidget);
 
     switch (defaultTargetPlatform) {
       case TargetPlatform.android:
         expect(find.byType(CupertinoTextSelectionToolbarButton), findsNWidgets(6));
+        expect(find.text('Cut'), findsOneWidget);
+        expect(find.text('Copy'), findsOneWidget);
+        expect(find.text('Paste'), findsOneWidget);
+        expect(find.text('Select All'), findsOneWidget);
+        expect(find.text('Share...'), findsOneWidget);
+        expect(findCupertinoOverflowNextButton(), findsOneWidget);
+
+        await tapCupertinoOverflowNextButton(tester);
+
+        expect(find.byType(CupertinoTextSelectionToolbarButton), findsNWidgets(4));
+        expect(findCupertinoOverflowBackButton(), findsOneWidget);
+        expect(find.text('Look Up'), findsOneWidget);
+        expect(find.text('Search Web'), findsOneWidget);
+        expect(findLiveTextButton(), findsOneWidget);
+
       case TargetPlatform.fuchsia:
-        expect(find.byType(CupertinoTextSelectionToolbarButton), findsNWidgets(6));
       case TargetPlatform.iOS:
         expect(find.byType(CupertinoTextSelectionToolbarButton), findsNWidgets(6));
-        expect(findOverflowNextButton(), findsOneWidget);
-        await tester.tapAt(tester.getCenter(findOverflowNextButton()));
-        await tester.pumpAndSettle();
+        expect(find.text('Cut'), findsOneWidget);
+        expect(find.text('Copy'), findsOneWidget);
+        expect(find.text('Paste'), findsOneWidget);
+        expect(find.text('Select All'), findsOneWidget);
+        expect(find.text('Look Up'), findsOneWidget);
+        expect(findCupertinoOverflowNextButton(), findsOneWidget);
+
+        await tapCupertinoOverflowNextButton(tester);
+
+        expect(find.byType(CupertinoTextSelectionToolbarButton), findsNWidgets(4));
+        expect(findCupertinoOverflowBackButton(), findsOneWidget);
+        expect(find.text('Search Web'), findsOneWidget);
+        expect(find.text('Share...'), findsOneWidget);
         expect(findLiveTextButton(), findsOneWidget);
+
       case TargetPlatform.macOS:
       case TargetPlatform.linux:
       case TargetPlatform.windows:
         expect(find.byType(CupertinoDesktopTextSelectionToolbarButton), findsNWidgets(8));
+        expect(find.text('Cut'), findsOneWidget);
+        expect(find.text('Copy'), findsOneWidget);
+        expect(find.text('Paste'), findsOneWidget);
+        expect(find.text('Select All'), findsOneWidget);
+        expect(find.text('Share...'), findsOneWidget);
+        expect(find.text('Look Up'), findsOneWidget);
+        expect(find.text('Search Web'), findsOneWidget);
+        expect(findLiveTextButton(), findsOneWidget);
     }
   },
     skip: kIsWeb, // [intended] on web the browser handles the context menu.

packages/flutter/test/material/adaptive_text_selection_toolbar_test.dart

@@ -11,6 +11,7 @@ import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';
 import '../widgets/clipboard_utils.dart';
 import '../widgets/editable_text_utils.dart';
 import '../widgets/live_text_utils.dart';
+import '../widgets/text_selection_toolbar_utils.dart';
 
 void main() {
   final MockClipboard mockClipboard = MockClipboard();
@@ -26,13 +27,6 @@ void main() {
     await Clipboard.setData(const ClipboardData(text: 'Clipboard data'));
   });
 
-  Finder findOverflowNextButton() {
-    return find.byWidgetPredicate((Widget widget) =>
-    widget is CustomPaint &&
-        '${widget.painter?.runtimeType}' == '_RightCupertinoChevronPainter',
-    );
-  }
-
   testWidgetsWithLeakTracking('Builds the right toolbar on each platform, including web, and shows buttonItems', (WidgetTester tester) async {
     const String buttonText = 'Click me';
 
@@ -206,30 +200,74 @@ void main() {
     );
 
     expect(find.byKey(key), findsOneWidget);
-    expect(find.text('Copy'), findsOneWidget);
-    expect(find.text('Cut'), findsOneWidget);
-    expect(find.text('Paste'), findsOneWidget);
 
     switch (defaultTargetPlatform) {
       case TargetPlatform.android:
-        expect(find.text('Select all'), findsOneWidget);
         expect(find.byType(TextSelectionToolbarTextButton), findsNWidgets(6));
-      case TargetPlatform.fuchsia:
+        expect(find.text('Cut'), findsOneWidget);
+        expect(find.text('Copy'), findsOneWidget);
+        expect(find.text('Paste'), findsOneWidget);
+        expect(find.text('Share'), findsOneWidget);
         expect(find.text('Select all'), findsOneWidget);
-        expect(find.byType(TextSelectionToolbarTextButton), findsNWidgets(8));
+        expect(find.text('Look Up'), findsOneWidget);
+        expect(findMaterialOverflowNextButton(), findsOneWidget); // Material overflow buttons are not TextSelectionToolbarTextButton.
+
+        await tapMaterialOverflowNextButton(tester);
+
+        expect(find.byType(TextSelectionToolbarTextButton), findsNWidgets(2));
+        expect(find.text('Search Web'), findsOneWidget);
+        expect(findLiveTextButton(), findsOneWidget);
+        expect(findMaterialOverflowBackButton(), findsOneWidget); // Material overflow buttons are not TextSelectionToolbarTextButton.
+
       case TargetPlatform.iOS:
-        expect(find.text('Select All'), findsOneWidget);
         expect(find.byType(CupertinoTextSelectionToolbarButton), findsNWidgets(6));
-        await tester.tapAt(tester.getCenter(findOverflowNextButton()));
-        await tester.pumpAndSettle();
+        expect(find.text('Cut'), findsOneWidget);
+        expect(find.text('Copy'), findsOneWidget);
+        expect(find.text('Paste'), findsOneWidget);
+        expect(find.text('Select All'), findsOneWidget);
+        expect(find.text('Look Up'), findsOneWidget);
+        expect(findCupertinoOverflowNextButton(), findsOneWidget);
+
+        await tapCupertinoOverflowNextButton(tester);
+
+        expect(find.byType(CupertinoTextSelectionToolbarButton), findsNWidgets(4));
+        expect(findCupertinoOverflowBackButton(), findsOneWidget);
+        expect(find.text('Search Web'), findsOneWidget);
+        expect(find.text('Share...'), findsOneWidget);
         expect(findLiveTextButton(), findsOneWidget);
+
+      case TargetPlatform.fuchsia:
+        expect(find.byType(TextSelectionToolbarTextButton), findsNWidgets(8));
+        expect(find.text('Cut'), findsOneWidget);
+        expect(find.text('Copy'), findsOneWidget);
+        expect(find.text('Paste'), findsOneWidget);
+        expect(find.text('Select all'), findsOneWidget);
+        expect(find.text('Look Up'), findsOneWidget);
+        expect(find.text('Search Web'), findsOneWidget);
+        expect(find.text('Share'), findsOneWidget);
+
       case TargetPlatform.linux:
       case TargetPlatform.windows:
-        expect(find.text('Select all'), findsOneWidget);
         expect(find.byType(DesktopTextSelectionToolbarButton), findsNWidgets(8));
+        expect(find.text('Cut'), findsOneWidget);
+        expect(find.text('Copy'), findsOneWidget);
+        expect(find.text('Paste'), findsOneWidget);
+        expect(find.text('Select all'), findsOneWidget);
+        expect(find.text('Look Up'), findsOneWidget);
+        expect(find.text('Search Web'), findsOneWidget);
+        expect(find.text('Share'), findsOneWidget);
+        expect(findLiveTextButton(), findsOneWidget);
+
       case TargetPlatform.macOS:
-        expect(find.text('Select All'), findsOneWidget);
         expect(find.byType(CupertinoDesktopTextSelectionToolbarButton), findsNWidgets(8));
+        expect(find.text('Cut'), findsOneWidget);
+        expect(find.text('Copy'), findsOneWidget);
+        expect(find.text('Paste'), findsOneWidget);
+        expect(find.text('Select All'), findsOneWidget);
+        expect(find.text('Look Up'), findsOneWidget);
+        expect(find.text('Search Web'), findsOneWidget);
+        expect(find.text('Share...'), findsOneWidget);
+        expect(findLiveTextButton(), findsOneWidget);
     }
   },
     skip: kIsWeb, // [intended] on web the browser handles the context menu.

packages/flutter/test/material/text_selection_test.dart

@@ -407,8 +407,9 @@ void main() {
       expect(find.text('Cut'), findsNothing);
       expect(find.text('Copy'), findsNothing);
       expect(find.text('Paste'), findsNothing);
+      expect(find.text('Share'), findsNothing);
       expect(find.text('Select all'), findsNothing);
-      expect(find.byType(IconButton), findsNothing);
+      expect(find.byType(IconButton), findsNothing); // 'More' button.
 
       // Tap to place the cursor and tap again to show the menu without a
       // selection.
@@ -426,6 +427,7 @@ void main() {
       expect(find.text('Cut'), findsNothing);
       expect(find.text('Copy'), findsNothing);
       expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share'), findsNothing);
       expect(find.text('Select all'), findsOneWidget);
       expect(find.byType(IconButton), findsNothing);
 
@@ -436,8 +438,9 @@ void main() {
       expect(find.text('Cut'), findsOneWidget);
       expect(find.text('Copy'), findsOneWidget);
       expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share'), findsNothing);
       expect(find.text('Select all'), findsNothing);
-      expect(find.byType(IconButton), findsNothing);
+      expect(find.byType(IconButton), findsOneWidget); // 'More' button.
       final Offset cutOffset = tester.getTopLeft(find.text('Cut'));
 
       // Tap to clear the selection.
@@ -447,37 +450,39 @@ void main() {
       expect(find.text('Copy'), findsNothing);
       expect(find.text('Paste'), findsNothing);
       expect(find.text('Select all'), findsNothing);
-      expect(find.byType(IconButton), findsNothing);
+      expect(find.byType(IconButton), findsNothing); // 'More' button.
 
       // Long press to show the menu.
       await tester.longPressAt(textOffsetToPosition(tester, 1));
       await tester.pumpAndSettle();
 
-      // The last button is missing, and a more button is shown.
+      // The last buttons (share and select all) are missing, and a more button is shown.
       expect(find.text('Cut'), findsOneWidget);
       expect(find.text('Copy'), findsOneWidget);
       expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share'), findsNothing);
       expect(find.text('Select all'), findsNothing);
-      expect(find.byType(IconButton), findsOneWidget);
+      expect(find.byType(IconButton), findsOneWidget); // 'More' button.
 
-      // Tapping the button shows the overflow menu.
+      // Tapping the more button shows the overflow menu.
       await tester.tap(find.byType(IconButton));
       await tester.pumpAndSettle();
       expect(find.text('Cut'), findsNothing);
       expect(find.text('Copy'), findsNothing);
       expect(find.text('Paste'), findsNothing);
+      expect(find.text('Share'), findsOneWidget);
       expect(find.text('Select all'), findsOneWidget);
-      expect(find.byType(IconButton), findsOneWidget);
+      expect(find.byType(IconButton), findsOneWidget); // Back button.
 
-      // Tapping Select all changes the menu items so that there is no longer
-      // any overflow.
+      // Tapping 'Select all' closes the overflow menu.
       await tester.tap(find.text('Select all'));
       await tester.pumpAndSettle();
       expect(find.text('Cut'), findsOneWidget);
       expect(find.text('Copy'), findsOneWidget);
       expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share'), findsNothing);
       expect(find.text('Select all'), findsNothing);
-      expect(find.byType(IconButton), findsNothing);
+      expect(find.byType(IconButton), findsOneWidget); // 'More' button.
       final Offset newCutOffset = tester.getTopLeft(find.text('Cut'));
       expect(newCutOffset, equals(cutOffset));
     },

packages/flutter/test/widgets/live_text_utils.dart

@@ -2,8 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+import 'package:flutter/cupertino.dart';
+import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
-import 'package:flutter/widgets.dart';
 import 'package:flutter_test/flutter_test.dart';
 
 /// A mock class to control the return result of Live Text input functions.
@@ -34,7 +35,23 @@ class LiveTextInputTester {
 }
 
 /// A function to find the live text button.
-Finder findLiveTextButton() => find.byWidgetPredicate((Widget widget) =>
-  widget is CustomPaint &&
-  '${widget.painter?.runtimeType}' == '_LiveTextIconPainter',
-);
+///
+/// LiveText button is displayed either using a custom painter,
+/// a Text with an empty label, or a Text with the 'Scan text' label.
+Finder findLiveTextButton() {
+  final bool isMobile = defaultTargetPlatform == TargetPlatform.android ||
+                        defaultTargetPlatform == TargetPlatform.fuchsia ||
+                        defaultTargetPlatform == TargetPlatform.iOS;
+  if (isMobile) {
+    return find.byWidgetPredicate((Widget widget) {
+      return (widget is CustomPaint && '${widget.painter?.runtimeType}' == '_LiveTextIconPainter')
+             || (widget is Text && widget.data == 'Scan text'); // Android and Fuchsia when inside a MaterialApp.
+    });
+  }
+  if (defaultTargetPlatform == TargetPlatform.macOS) {
+    return find.ancestor(of: find.text(''), matching: find.byType(CupertinoDesktopTextSelectionToolbarButton));
+  }
+  return find.byWidgetPredicate((Widget widget) {
+    return widget is Text && (widget.data == '' || widget.data == 'Scan text');
+  });
+}

packages/flutter/test/widgets/text_selection_toolbar_utils.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/cupertino.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter/src/foundation/platform.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../widgets/editable_text_utils.dart';
+
+Finder findCupertinoOverflowNextButton() {
+  return find.byWidgetPredicate((Widget widget) {
+    return widget is CustomPaint && '${widget.painter?.runtimeType}' == '_RightCupertinoChevronPainter';
+  });
+}
+
+Finder findCupertinoOverflowBackButton() {
+  return find.byWidgetPredicate((Widget widget) {
+    return widget is CustomPaint && '${widget.painter?.runtimeType}' == '_LeftCupertinoChevronPainter';
+  });
+}
+
+Future<void> tapCupertinoOverflowNextButton(WidgetTester tester) async{
+  await tester.tapAt(tester.getCenter(findCupertinoOverflowNextButton()));
+  await tester.pumpAndSettle();
+}
+
+void expectNoCupertinoToolbar() {
+  expect(find.byType(CupertinoButton), findsNothing);
+}
+
+// Check that the Cupertino text selection toolbars show the expected buttons
+// when the content is partially selected.
+void expectCupertinoToolbarForPartialSelection() {
+  if (isContextMenuProvidedByPlatform) {
+    expectNoCupertinoToolbar();
+    return;
+  }
+
+  switch (defaultTargetPlatform) {
+    case TargetPlatform.android:
+      expect(find.byType(CupertinoButton), findsNWidgets(5));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share...'), findsOneWidget);
+      expect(find.text('Select All'), findsOneWidget);
+    case TargetPlatform.iOS:
+      expect(find.byType(CupertinoButton), findsNWidgets(6));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share...'), findsOneWidget);
+      expect(find.text('Look Up'), findsOneWidget);
+      expect(find.text('Search Web'), findsOneWidget);
+    case TargetPlatform.macOS:
+      expect(find.byType(CupertinoButton), findsNWidgets(3));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+    case TargetPlatform.fuchsia:
+    case TargetPlatform.linux:
+    case TargetPlatform.windows:
+      expect(find.byType(CupertinoButton), findsNWidgets(4));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Select All'), findsOneWidget);
+  }
+}
+
+// Check that the Cupertino text selection toolbar shows the expected buttons
+// when the content is fully selected.
+void expectCupertinoToolbarForFullSelection() {
+  if (isContextMenuProvidedByPlatform) {
+    expectNoCupertinoToolbar();
+    return;
+  }
+
+  switch (defaultTargetPlatform) {
+    case TargetPlatform.android:
+      expect(find.byType(CupertinoButton), findsNWidgets(4));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share...'), findsOneWidget);
+    case TargetPlatform.iOS:
+      expect(find.byType(CupertinoButton), findsNWidgets(6));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share...'), findsOneWidget);
+      expect(find.text('Look Up'), findsOneWidget);
+      expect(find.text('Search Web'), findsOneWidget);
+    case TargetPlatform.fuchsia:
+    case TargetPlatform.linux:
+    case TargetPlatform.macOS:
+    case TargetPlatform.windows:
+      expect(find.byType(CupertinoButton), findsNWidgets(3));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+  }
+}
+
+// Check that the Cupertino text selection toolbar is correct for a collapsed selection.
+void expectCupertinoToolbarForCollapsedSelection() {
+  if (isContextMenuProvidedByPlatform) {
+    expectNoCupertinoToolbar();
+    return;
+  }
+
+  switch (defaultTargetPlatform) {
+    case TargetPlatform.android:
+      expect(find.byType(CupertinoButton), findsNWidgets(4));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share...'), findsOneWidget);
+    case TargetPlatform.iOS:
+      expect(find.byType(CupertinoButton), findsNWidgets(2));
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Select All'), findsOneWidget);
+    case TargetPlatform.fuchsia:
+    case TargetPlatform.linux:
+    case TargetPlatform.windows:
+    case TargetPlatform.macOS:
+      expect(find.byType(CupertinoButton), findsNWidgets(1));
+      expect(find.text('Paste'), findsOneWidget);
+  }
+}
+
+void expectNoMaterialToolbar() {
+  expect(find.byType(TextButton), findsNothing);
+}
+
+// Check that the Material text selection toolbars show the expected buttons
+// when the content is partially selected.
+void expectMaterialToolbarForPartialSelection() {
+  if (isContextMenuProvidedByPlatform) {
+    expectNoMaterialToolbar();
+    return;
+  }
+
+  switch (defaultTargetPlatform) {
+    case TargetPlatform.android:
+      expect(find.byType(TextButton), findsNWidgets(5));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share'), findsOneWidget);
+      expect(find.text('Select all'), findsOneWidget);
+    case TargetPlatform.iOS:
+    case TargetPlatform.macOS:
+    case TargetPlatform.fuchsia:
+    case TargetPlatform.linux:
+    case TargetPlatform.windows:
+      expect(find.byType(TextButton), findsNWidgets(4));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Select all'), findsOneWidget);
+  }
+}
+
+// Check that the Material text selection toolbar shows the expected buttons
+// when the content is fully selected.
+void expectMaterialToolbarForFullSelection() {
+  if (isContextMenuProvidedByPlatform) {
+    expectNoMaterialToolbar();
+    return;
+  }
+
+  switch (defaultTargetPlatform) {
+    case TargetPlatform.android:
+      expect(find.byType(TextButton), findsNWidgets(4));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+      expect(find.text('Share'), findsOneWidget);
+    case TargetPlatform.iOS:
+    case TargetPlatform.fuchsia:
+    case TargetPlatform.linux:
+    case TargetPlatform.macOS:
+    case TargetPlatform.windows:
+      expect(find.byType(TextButton), findsNWidgets(3));
+      expect(find.text('Cut'), findsOneWidget);
+      expect(find.text('Copy'), findsOneWidget);
+      expect(find.text('Paste'), findsOneWidget);
+  }
+}
+
+Finder findMaterialOverflowNextButton() {
+  return find.byIcon(Icons.more_vert);
+}
+
+Finder findMaterialOverflowBackButton() {
+  return find.byIcon(Icons.arrow_back);
+}
+
+Future<void> tapMaterialOverflowNextButton(WidgetTester tester) async {
+  await tester.tapAt(tester.getCenter(findMaterialOverflowNextButton()));
+  await tester.pumpAndSettle();
+}