ClipboardStatusNotifier should handle errors in Clipboard.getData (#64012)

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

@@ -1512,7 +1512,7 @@ class ClipboardStatusNotifier extends ValueNotifier<ClipboardStatus> with Widget
   bool get disposed => _disposed;
 
   /// Check the [Clipboard] and update [value] if needed.
-  void update() {
+  Future<void> update() async {
     // iOS 14 added a notification that appears when an app accesses the
     // clipboard. To avoid the notification, don't access the clipboard on iOS,
     // and instead always shown the paste button, even when the clipboard is
@@ -1532,15 +1532,26 @@ class ClipboardStatusNotifier extends ValueNotifier<ClipboardStatus> with Widget
         break;
     }
 
-    Clipboard.getData(Clipboard.kTextPlain).then((ClipboardData data) {
-      final ClipboardStatus clipboardStatus = data != null && data.text != null && data.text.isNotEmpty
-          ? ClipboardStatus.pasteable
-          : ClipboardStatus.notPasteable;
-      if (_disposed || clipboardStatus == value) {
+    ClipboardData data;
+    try {
+      data = await Clipboard.getData(Clipboard.kTextPlain);
+    } catch (stacktrace) {
+      // In the case of an error from the Clipboard API, set the value to
+      // unknown so that it will try to update again later.
+      if (_disposed || value == ClipboardStatus.unknown) {
         return;
       }
-      value = clipboardStatus;
-    });
+      value = ClipboardStatus.unknown;
+      return;
+    }
+
+    final ClipboardStatus clipboardStatus = data != null && data.text != null && data.text.isNotEmpty
+        ? ClipboardStatus.pasteable
+        : ClipboardStatus.notPasteable;
+    if (_disposed || clipboardStatus == value) {
+      return;
+    }
+    value = clipboardStatus;
   }
 
   @override

packages/flutter/test/widgets/text_selection_test.dart

@@ -6,9 +6,34 @@
 
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/gestures.dart' show PointerDeviceKind;
-import 'package:flutter/widgets.dart';
-import 'package:flutter/rendering.dart';
 import 'package:flutter/material.dart';
+import 'package:flutter/rendering.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter/widgets.dart';
+
+class MockClipboard {
+  MockClipboard({
+    this.getDataThrows = false,
+  });
+
+  final bool getDataThrows;
+
+  Object _clipboardData = <String, dynamic>{
+    'text': null,
+  };
+
+  Future<dynamic> handleMethodCall(MethodCall methodCall) async {
+    switch (methodCall.method) {
+      case 'Clipboard.getData':
+        if (getDataThrows) {
+          throw Exception();
+        }
+        return _clipboardData;
+      case 'Clipboard.setData':
+        _clipboardData = methodCall.arguments;
+    }
+  }
+}
 
 void main() {
   int tapCount;
@@ -608,6 +633,56 @@ void main() {
     expect(hitRect.size.width, lessThan(textFieldRect.size.width));
     expect(hitRect.size.height, lessThan(textFieldRect.size.height));
   }, variant: const TargetPlatformVariant(<TargetPlatform>{ TargetPlatform.iOS,  TargetPlatform.macOS }));
+
+  group('ClipboardStatusNotifier', () {
+    group('when Clipboard fails', () {
+      setUp(() {
+        final MockClipboard mockClipboard = MockClipboard(getDataThrows: true);
+        SystemChannels.platform.setMockMethodCallHandler(mockClipboard.handleMethodCall);
+      });
+
+      tearDown(() {
+        SystemChannels.platform.setMockMethodCallHandler(null);
+      });
+
+      test('Clipboard API failure is gracefully recovered from', () async {
+        final ClipboardStatusNotifier notifier = ClipboardStatusNotifier();
+        expect(notifier.value, ClipboardStatus.unknown);
+
+        await expectLater(notifier.update(), completes);
+        expect(notifier.value, ClipboardStatus.unknown);
+      });
+    });
+
+    group('when Clipboard succeeds', () {
+      final MockClipboard mockClipboard = MockClipboard();
+
+      setUp(() {
+        SystemChannels.platform.setMockMethodCallHandler(mockClipboard.handleMethodCall);
+      });
+
+      tearDown(() {
+        SystemChannels.platform.setMockMethodCallHandler(null);
+      });
+
+      test('update sets value based on clipboard contents', () async {
+        final ClipboardStatusNotifier notifier = ClipboardStatusNotifier();
+        expect(notifier.value, ClipboardStatus.unknown);
+
+        await expectLater(notifier.update(), completes);
+        expect(notifier.value, ClipboardStatus.notPasteable);
+
+        mockClipboard.handleMethodCall(const MethodCall(
+          'Clipboard.setData',
+          <String, dynamic>{
+            'text': 'pasteablestring',
+          },
+        ));
+        await expectLater(notifier.update(), completes);
+        expect(notifier.value, ClipboardStatus.pasteable);
+      });
+    });
+  });
 }
 
 class FakeTextSelectionGestureDetectorBuilderDelegate implements TextSelectionGestureDetectorBuilderDelegate {