Apply BindingBase.checkInstance to TestDefaultBinaryMessengerBinding (#116937)

packages/flutter/test/cupertino/adaptive_text_selection_toolbar_test.dart

@@ -13,7 +13,7 @@ void main() {
   final MockClipboard mockClipboard = MockClipboard();
 
   setUp(() async {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       mockClipboard.handleMethodCall,
     );
@@ -23,7 +23,7 @@ void main() {
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       null,
     );

packages/flutter/test/cupertino/text_field_test.dart

@@ -159,7 +159,7 @@ class PathPointsMatcher extends Matcher {
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
   final MockClipboard mockClipboard = MockClipboard();
-  TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
+  TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
 
   // Returns the first RenderEditable.
   RenderEditable findRenderEditable(WidgetTester tester) {

packages/flutter/test/cupertino/text_selection_test.dart

@@ -82,7 +82,7 @@ void main() {
   }
 
   setUp(() async {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       mockClipboard.handleMethodCall,
     );
@@ -92,7 +92,7 @@ void main() {
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       null,
     );

packages/flutter/test/foundation/service_extensions_test.dart

@@ -546,7 +546,7 @@ void main() {
     bool completed;
 
     completed = false;
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler('flutter/assets', (ByteData? message) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler('flutter/assets', (ByteData? message) async {
       expect(utf8.decode(message!.buffer.asUint8List()), 'test');
       completed = true;
       return ByteData(5); // 0x0000000000
@@ -573,7 +573,7 @@ void main() {
     });
     expect(data, isFalse);
     expect(completed, isTrue);
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler('flutter/assets', null);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler('flutter/assets', null);
   });
 
   test('Service extensions - exit', () async {

packages/flutter/test/material/adaptive_text_selection_toolbar_test.dart

@@ -16,7 +16,7 @@ void main() {
 
   setUp(() async {
     TestWidgetsFlutterBinding.ensureInitialized();
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       mockClipboard.handleMethodCall,
     );

packages/flutter/test/material/feedback_test.dart

@@ -27,14 +27,14 @@ void main () {
 
     setUp(() {
       semanticEvents = <Map<String, Object>>[];
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockDecodedMessageHandler<dynamic>(SystemChannels.accessibility, (dynamic message) async {
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockDecodedMessageHandler<dynamic>(SystemChannels.accessibility, (dynamic message) async {
         final Map<dynamic, dynamic> typedMessage = message as Map<dynamic, dynamic>;
         semanticEvents.add(typedMessage.cast<String, Object>());
       });
     });
 
     tearDown(() {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockDecodedMessageHandler<dynamic>(SystemChannels.accessibility, null);
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockDecodedMessageHandler<dynamic>(SystemChannels.accessibility, null);
     });
 
     testWidgets('forTap', (WidgetTester tester) async {

packages/flutter/test/material/feedback_tester.dart

@@ -11,7 +11,7 @@ import 'package:flutter_test/flutter_test.dart';
 /// cannot be used in combination with other classes that do the same.
 class FeedbackTester {
   FeedbackTester() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, _handler);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, _handler);
   }
 
   /// Number of times haptic feedback was requested (vibration).
@@ -34,7 +34,7 @@ class FeedbackTester {
 
   /// Stops tracking.
   void dispose() {
-    assert(TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.checkMockMessageHandler(SystemChannels.platform.name, _handler));
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+    assert(TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.checkMockMessageHandler(SystemChannels.platform.name, _handler));
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
   }
 }

packages/flutter/test/material/search_test.dart

@@ -17,12 +17,12 @@ void main() {
   setUp(() async {
     // Fill the clipboard so that the Paste option is available in the text
     // selection menu.
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
     await Clipboard.setData(const ClipboardData(text: 'Clipboard data'));
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
   });
 
   testWidgets('Changing query moves cursor to the end of query', (WidgetTester tester) async {

packages/flutter/test/material/text_field_test.dart

@@ -176,7 +176,7 @@ void main() {
 
   setUp(() async {
     debugResetSemanticsIdCounter();
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       mockClipboard.handleMethodCall,
     );
@@ -186,7 +186,7 @@ void main() {
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       null,
     );

packages/flutter/test/material/text_form_field_test.dart

@@ -17,7 +17,7 @@ import '../widgets/editable_text_utils.dart';
 void main() {
   TestWidgetsFlutterBinding.ensureInitialized();
   final MockClipboard mockClipboard = MockClipboard();
-  TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
+  TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
 
   setUp(() async {
     // Fill the clipboard so that the Paste option is available in the text

packages/flutter/test/material/text_selection_test.dart

@@ -20,7 +20,7 @@ void main() {
   final MockClipboard mockClipboard = MockClipboard();
 
   setUp(() async {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
         .setMockMethodCallHandler(
           SystemChannels.platform,
           mockClipboard.handleMethodCall,
@@ -31,7 +31,7 @@ void main() {
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       null,
     );

packages/flutter/test/semantics/semantics_service_test.dart

@@ -17,7 +17,7 @@ void main() {
       log.add(message);
     }
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockDecodedMessageHandler<dynamic>(SystemChannels.accessibility, handleMessage);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockDecodedMessageHandler<dynamic>(SystemChannels.accessibility, handleMessage);
 
     await SemanticsService.announce('announcement 1', TextDirection.ltr);
     await SemanticsService.announce('announcement 2', TextDirection.rtl, assertiveness: Assertiveness.assertive);

packages/flutter/test/services/browser_context_menu_test.dart

@@ -41,15 +41,15 @@ void main() {
     group('disableContextMenu', () {
       // Make sure the context menu is enabled (default) after the test.
       tearDown(() async {
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, (MethodCall methodCall) {
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, (MethodCall methodCall) {
           return null;
         });
         await BrowserContextMenu.enableContextMenu();
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, null);
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, null);
       });
 
       test('disableContextMenu calls its platform channel method', () async {
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, (MethodCall methodCall) async {
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, (MethodCall methodCall) async {
           log.add(methodCall);
           return null;
         });
@@ -58,13 +58,13 @@ void main() {
           isMethodCall('disableContextMenu', arguments: null),
         ]);
 
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, null);
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, null);
       });
     });
 
     group('enableContextMenu', () {
       test('enableContextMenu calls its platform channel method', () async {
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, (MethodCall methodCall) async {
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, (MethodCall methodCall) async {
           log.add(methodCall);
           return null;
         });
@@ -73,7 +73,7 @@ void main() {
           isMethodCall('enableContextMenu', arguments: null),
         ]);
 
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, null);
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.contextMenu, null);
       });
     });
   },

packages/flutter/test/services/default_binary_messenger_test.dart

@@ -53,7 +53,7 @@ void main() {
 
   test('can check the mock handler', () {
     Future<ByteData?> handler(ByteData? call) => Future<ByteData?>.value();
-    final TestDefaultBinaryMessenger messenger = TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger;
+    final TestDefaultBinaryMessenger messenger = TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger;
 
     expect(messenger.checkMockMessageHandler('test_channel', null), true);
     expect(messenger.checkMockMessageHandler('test_channel', handler), false);

packages/flutter/test/services/deferred_component_test.dart

@@ -11,7 +11,7 @@ void main() {
   test('installDeferredComponent test', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.deferredComponent, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.deferredComponent, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -28,7 +28,7 @@ void main() {
   test('uninstallDeferredComponent test', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.deferredComponent, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.deferredComponent, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });

packages/flutter/test/services/fake_platform_views.dart

@@ -151,7 +151,7 @@ class FakeAndroidViewController implements AndroidViewController {
 
 class FakeAndroidPlatformViewsController {
   FakeAndroidPlatformViewsController() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform_views, _onMethodCall);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform_views, _onMethodCall);
   }
 
   Iterable<FakeAndroidPlatformView> get views => _views.values;
@@ -370,7 +370,7 @@ class FakeAndroidPlatformViewsController {
 
 class FakeIosPlatformViewsController {
   FakeIosPlatformViewsController() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform_views, _onMethodCall);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform_views, _onMethodCall);
   }
 
   Iterable<FakeUiKitView> get views => _views.values;
@@ -473,7 +473,7 @@ class FakeIosPlatformViewsController {
 
 class FakeHtmlPlatformViewsController {
   FakeHtmlPlatformViewsController() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform_views, _onMethodCall);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform_views, _onMethodCall);
   }
 
   Iterable<FakeHtmlPlatformView> get views => _views.values;

packages/flutter/test/services/haptic_feedback_test.dart

@@ -11,7 +11,7 @@ void main() {
   test('Haptic feedback control test', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -26,7 +26,7 @@ void main() {
     Future<void> callAndVerifyHapticFunction(Future<void> Function() hapticFunction, String platformMethodArgument) async {
       final List<MethodCall> log = <MethodCall>[];
 
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
         log.add(methodCall);
         return null;
       });

packages/flutter/test/services/platform_channel_test.dart

@@ -19,7 +19,7 @@ void main() {
     const MessageCodec<String?> string = StringCodec();
     const BasicMessageChannel<String?> channel = BasicMessageChannel<String?>('ch', string);
     test('can send string message and get reply', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch',
         (ByteData? message) async => string.encodeMessage('${string.decodeMessage(message)!} world'),
       );
@@ -30,7 +30,7 @@ void main() {
     test('can receive string message and send reply', () async {
       channel.setMessageHandler((String? message) async => '${message!} world');
       String? reply;
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         'ch',
         const StringCodec().encodeMessage('hello'),
         (ByteData? replyBinary) {
@@ -47,7 +47,7 @@ void main() {
     const MethodChannel channel = MethodChannel('ch7', jsonMethod);
     const OptionalMethodChannel optionalMethodChannel = OptionalMethodChannel('ch8', jsonMethod);
     test('can invoke method and get result', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch7',
         (ByteData? message) async {
           final Map<dynamic, dynamic> methodCall = jsonMessage.decodeMessage(message) as Map<dynamic, dynamic>;
@@ -63,7 +63,7 @@ void main() {
     });
 
     test('can invoke list method and get result', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch7',
         (ByteData? message) async {
           final Map<dynamic, dynamic> methodCall = jsonMessage.decodeMessage(message) as Map<dynamic, dynamic>;
@@ -79,7 +79,7 @@ void main() {
     });
 
     test('can invoke list method and get null result', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch7',
         (ByteData? message) async {
           final Map<dynamic, dynamic> methodCall = jsonMessage.decodeMessage(message) as Map<dynamic, dynamic>;
@@ -94,7 +94,7 @@ void main() {
     });
 
     test('can invoke map method and get result', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch7',
         (ByteData? message) async {
           final Map<dynamic, dynamic> methodCall = jsonMessage.decodeMessage(message) as Map<dynamic, dynamic>;
@@ -110,7 +110,7 @@ void main() {
     });
 
     test('can invoke map method and get null result', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch7',
         (ByteData? message) async {
           final Map<dynamic, dynamic> methodCall = jsonMessage.decodeMessage(message) as Map<dynamic, dynamic>;
@@ -125,7 +125,7 @@ void main() {
     });
 
     test('can invoke method and get error', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch7',
         (ByteData? message) async {
           return jsonMessage.encodeMessage(<dynamic>[
@@ -147,7 +147,7 @@ void main() {
     });
 
     test('can invoke unimplemented method', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch7',
         (ByteData? message) async => null,
       );
@@ -164,7 +164,7 @@ void main() {
     });
 
     test('can invoke unimplemented method (optional)', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch8',
         (ByteData? message) async => null,
       );
@@ -176,7 +176,7 @@ void main() {
       channel.setMethodCallHandler(null);
       final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData? envelope;
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
         envelope = result;
       });
       await null; // just in case there's something async happening
@@ -186,7 +186,7 @@ void main() {
     test('can handle method call with no registered plugin (setting after)', () async {
       final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData? envelope;
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
         envelope = result;
       });
       channel.setMethodCallHandler(null);
@@ -200,7 +200,7 @@ void main() {
       });
       final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData? envelope;
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
         envelope = result;
       });
       expect(envelope, isNull);
@@ -210,7 +210,7 @@ void main() {
       channel.setMethodCallHandler((MethodCall call) async => '${call.arguments}, world');
       final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData? envelope;
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
         envelope = result;
       });
       expect(jsonMethod.decodeEnvelope(envelope!), equals('hello, world'));
@@ -222,7 +222,7 @@ void main() {
       });
       final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData? envelope;
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
         envelope = result;
       });
       expect(
@@ -242,7 +242,7 @@ void main() {
       });
       final ByteData call = jsonMethod.encodeMethodCall(const MethodCall('sayHello', 'hello'));
       ByteData? envelope;
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage('ch7', call, (ByteData? result) {
         envelope = result;
       });
       expect(
@@ -260,10 +260,10 @@ void main() {
       Future<dynamic> handler(MethodCall call) => Future<dynamic>.value();
 
       const MethodChannel channel = MethodChannel('test_handler');
-      expect(TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.checkMockMessageHandler(channel.name, null), true);
-      expect(TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.checkMockMessageHandler(channel.name, handler), false);
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(channel, handler);
-      expect(TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.checkMockMessageHandler(channel.name, handler), true);
+      expect(TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.checkMockMessageHandler(channel.name, null), true);
+      expect(TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.checkMockMessageHandler(channel.name, handler), false);
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(channel, handler);
+      expect(TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.checkMockMessageHandler(channel.name, handler), true);
     });
   });
 
@@ -272,7 +272,7 @@ void main() {
     const MethodCodec jsonMethod = JSONMethodCodec();
     const EventChannel channel = EventChannel('ch', jsonMethod);
     void emitEvent(ByteData? event) {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         'ch',
         event,
         (ByteData? reply) {},
@@ -280,7 +280,7 @@ void main() {
     }
     test('can receive event stream', () async {
       bool canceled = false;
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch',
         (ByteData? message) async {
           final Map<dynamic, dynamic> methodCall = jsonMessage.decodeMessage(message) as Map<dynamic, dynamic>;
@@ -305,7 +305,7 @@ void main() {
     });
 
     test('can receive error event', () async {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(
         'ch',
         (ByteData? message) async {
           final Map<dynamic, dynamic> methodCall = jsonMessage.decodeMessage(message) as Map<dynamic, dynamic>;

packages/flutter/test/services/platform_messages_test.dart

@@ -14,18 +14,18 @@ void main() {
   test('Mock binary message handler control test', () async {
     final List<ByteData?> log = <ByteData>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler('test1', (ByteData? message) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler('test1', (ByteData? message) async {
       log.add(message);
       return null;
     });
 
     final ByteData message = ByteData(2)..setUint16(0, 0xABCD);
-    await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.send('test1', message);
+    await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.send('test1', message);
     expect(log, equals(<ByteData>[message]));
     log.clear();
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler('test1', null);
-    await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.send('test1', message);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler('test1', null);
+    await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.send('test1', message);
     expect(log, isEmpty);
   });
 }

packages/flutter/test/services/raw_keyboard_test.dart

@@ -211,7 +211,7 @@ void main() {
       // when this event is received, but it's not in keysPressed yet.
       data['modifiers'] = (data['modifiers'] as int) | RawKeyEventDataMacOs.modifierLeftShift | RawKeyEventDataMacOs.modifierShift;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {},
@@ -235,7 +235,7 @@ void main() {
       // when this event is received, but it's not in keysPressed yet.
       data['modifiers'] = (data['modifiers'] as int) | RawKeyEventDataMacOs.modifierLeftShift | RawKeyEventDataMacOs.modifierShift;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {},
@@ -259,7 +259,7 @@ void main() {
       // when this event is received, but it's not in keysPressed yet.
       data['modifiers'] = (data['modifiers'] as int) | RawKeyEventDataWindows.modifierLeftShift | RawKeyEventDataWindows.modifierShift;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {},
@@ -283,7 +283,7 @@ void main() {
       // when this event is received, but it's not in keysPressed yet.
       data['metaState'] = (data['metaState'] as int) | RawKeyEventDataAndroid.modifierLeftShift | RawKeyEventDataAndroid.modifierShift;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {},
@@ -307,7 +307,7 @@ void main() {
       // when this event is received, but it's not in keysPressed yet.
       data['modifiers'] = (data['modifiers'] as int) | RawKeyEventDataFuchsia.modifierLeftShift;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {},
@@ -331,7 +331,7 @@ void main() {
       // when this event is received, but it's not in keysPressed yet.
       data['modifiers'] = (data['modifiers'] as int) | GLFWKeyHelper.modifierShift;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {},
@@ -363,7 +363,7 @@ void main() {
       // since we're only testing if the raw keyboard can handle the message.
       // In a real application, the embedder responder will send the correct key data
       // (which is tested in the engine).
-      TestDefaultBinaryMessengerBinding.instance!.keyEventManager.handleKeyData(const ui.KeyData(
+      TestDefaultBinaryMessengerBinding.instance.keyEventManager.handleKeyData(const ui.KeyData(
         type: ui.KeyEventType.down,
         timeStamp: Duration.zero,
         logical: 0,
@@ -371,7 +371,7 @@ void main() {
         character: null,
         synthesized: false,
       ));
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {},
@@ -425,7 +425,7 @@ void main() {
       addTearDown(() {
         RawKeyboard.instance.removeListener(events.add);
       });
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(const <String, dynamic>{
           'type': 'keydown',
@@ -460,7 +460,7 @@ void main() {
       );
       data['metaState'] = (data['metaState'] as int) | RawKeyEventDataWeb.modifierShift;
       // Dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {},
@@ -551,7 +551,7 @@ void main() {
         RawKeyEventDataAndroid.modifierControl |
         RawKeyEventDataAndroid.modifierMeta;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
             (ByteData? data) {},
@@ -588,7 +588,7 @@ void main() {
           RawKeyEventDataMacOs.modifierCommand |
           RawKeyEventDataMacOs.modifierControl;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
             (ByteData? data) {},
@@ -705,7 +705,7 @@ void main() {
           RawKeyEventDataWindows.modifierAlt |
           RawKeyEventDataWindows.modifierControl;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
             (ByteData? data) {},
@@ -741,7 +741,7 @@ void main() {
         GLFWKeyHelper.modifierControl |
         GLFWKeyHelper.modifierMeta;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
             (ByteData? data) {},
@@ -778,7 +778,7 @@ void main() {
         RawKeyEventDataWeb.modifierControl |
         RawKeyEventDataWeb.modifierMeta;
       // dispatch the modified data.
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
             (ByteData? data) {},
@@ -819,7 +819,7 @@ void main() {
 
       expect(
         () async {
-          await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+          await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
             SystemChannels.keyEvent.name,
             SystemChannels.keyEvent.codec.encodeMessage(keyEventMessage),
             (ByteData? data) { },
@@ -840,7 +840,7 @@ void main() {
       addTearDown(() {
         RawKeyboard.instance.removeListener(events.add);
       });
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(const <String, dynamic>{
           'type': 'keydown',
@@ -868,7 +868,7 @@ void main() {
       addTearDown(() {
         RawKeyboard.instance.removeListener(events.add);
       });
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(const <String, dynamic>{
           'type': 'keydown',
@@ -899,7 +899,7 @@ void main() {
       addTearDown(() {
         RawKeyboard.instance.removeListener(events.add);
       });
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(const <String, dynamic>{
           'type': 'keydown',
@@ -928,7 +928,7 @@ void main() {
       addTearDown(() {
         RawKeyboard.instance.removeListener(events.add);
       });
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(const <String, dynamic>{
           'type': 'keydown',
@@ -1296,7 +1296,7 @@ void main() {
         platform: 'android',
       );
       Map<String, Object?>? message;
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {
@@ -1320,7 +1320,7 @@ void main() {
       focusNode.requestFocus();
       await tester.pump();
 
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(data),
         (ByteData? data) {

packages/flutter/test/services/system_chrome_test.dart

@@ -12,7 +12,7 @@ void main() {
   testWidgets('SystemChrome overlay style test', (WidgetTester tester) async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -70,7 +70,7 @@ void main() {
   test('setPreferredOrientations control test', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -89,7 +89,7 @@ void main() {
   test('setApplicationSwitcherDescription control test', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -108,7 +108,7 @@ void main() {
   test('setApplicationSwitcherDescription missing plugin', () async {
     final List<ByteData?> log = <ByteData>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler('flutter/platform', (ByteData? message) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler('flutter/platform', (ByteData? message) async {
       log.add(message);
       return null;
     });
@@ -120,10 +120,11 @@ void main() {
     expect(log, isNotEmpty);
   });
 
+
   test('setEnabledSystemUIMode control test', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -152,7 +153,7 @@ void main() {
   test('setEnabledSystemUIMode passes correct overlays for manual configuration', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -169,7 +170,7 @@ void main() {
   test('setSystemUIChangeCallback control test', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });

packages/flutter/test/services/system_navigator_test.dart

@@ -18,7 +18,7 @@ void main() {
   }
 
   test('System navigator control test - platform messages', () async {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -27,11 +27,11 @@ void main() {
       isMethodCall('SystemNavigator.pop', arguments: null),
     ]);
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
   });
 
   test('System navigator control test - navigation messages', () async {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.navigation, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.navigation, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });
@@ -56,6 +56,6 @@ void main() {
       isMethodCall('routeInformationUpdated', arguments: <String, dynamic>{ 'location': 'a', 'state': true, 'replace': true }),
     ]);
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.navigation, null);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.navigation, null);
   });
 }

packages/flutter/test/services/system_sound_test.dart

@@ -12,7 +12,7 @@ void main() {
   test('System sound control test', () async {
     final List<MethodCall> log = <MethodCall>[];
 
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, (MethodCall methodCall) async {
       log.add(methodCall);
       return null;
     });

packages/flutter/test/widgets/editable_text_shortcuts_test.dart

@@ -26,12 +26,12 @@ void main() {
   final MockClipboard mockClipboard = MockClipboard();
 
   setUp(() async {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
     await Clipboard.setData(const ClipboardData(text: 'empty'));
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
   });
 
   const String testText =

packages/flutter/test/widgets/router_test.dart

@@ -823,8 +823,7 @@ testWidgets('ChildBackButtonDispatcher take priority recursively', (WidgetTester
   testWidgets('PlatformRouteInformationProvider updates route information', (WidgetTester tester) async {
     final List<MethodCall> log = <MethodCall>[];
     TestDefaultBinaryMessengerBinding
-      .instance!
-      .defaultBinaryMessenger
+      .instance.defaultBinaryMessenger
       .setMockMethodCallHandler(
         SystemChannels.navigation,
         (MethodCall methodCall) async {

packages/flutter/test/widgets/scrollable_selection_test.dart

@@ -27,12 +27,12 @@ void main() {
   final MockClipboard mockClipboard = MockClipboard();
 
   setUp(() async {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
     await Clipboard.setData(const ClipboardData(text: 'empty'));
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
   });
 
   testWidgets('mouse can select multiple widgets', (WidgetTester tester) async {

packages/flutter/test/widgets/selectable_region_test.dart

@@ -28,12 +28,12 @@ void main() {
   final MockClipboard mockClipboard = MockClipboard();
 
   setUp(() async {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
     await Clipboard.setData(const ClipboardData(text: 'empty'));
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
   });
 
   group('SelectableRegion', () {

packages/flutter/test/widgets/selectable_text_test.dart

@@ -146,7 +146,7 @@ void main() {
 
   setUp(() async {
     debugResetSemanticsIdCounter();
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       mockClipboard.handleMethodCall,
     );
@@ -156,7 +156,7 @@ void main() {
   });
 
   tearDown(() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(
       SystemChannels.platform,
       null,
     );

packages/flutter/test/widgets/text_selection_test.dart

@@ -1374,11 +1374,11 @@ void main() {
     group('when Clipboard fails', () {
       setUp(() {
         final MockClipboard mockClipboard = MockClipboard(hasStringsThrows: true);
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
       });
 
       tearDown(() {
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
       });
 
       test('Clipboard API failure is gracefully recovered from', () async {
@@ -1394,11 +1394,11 @@ void main() {
       final MockClipboard mockClipboard = MockClipboard();
 
       setUp(() {
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, mockClipboard.handleMethodCall);
       });
 
       tearDown(() {
-        TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
+        TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(SystemChannels.platform, null);
       });
 
       test('update sets value based on clipboard contents', () async {

packages/flutter_test/lib/src/binding.dart

@@ -99,7 +99,7 @@ mixin TestDefaultBinaryMessengerBinding on BindingBase, ServicesBinding {
   }
 
   /// The current [TestDefaultBinaryMessengerBinding], if one has been created.
-  static TestDefaultBinaryMessengerBinding? get instance => _instance;
+  static TestDefaultBinaryMessengerBinding get instance => BindingBase.checkInstance(_instance);
   static TestDefaultBinaryMessengerBinding? _instance;
 
   @override
@@ -775,10 +775,10 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
     assert(inTest);
 
     // Set the handler only if there is currently none.
-    if (TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+    if (TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
         .checkMockMessageHandler(SystemChannels.accessibility.name, null)) {
       _announcementHandler = _handleAnnouncementMessage;
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
           .setMockDecodedMessageHandler<dynamic>(
               SystemChannels.accessibility, _announcementHandler);
     }
@@ -1067,10 +1067,10 @@ abstract class TestWidgetsFlutterBinding extends BindingBase
     _parentZone = null;
     buildOwner!.focusManager.dispose();
 
-    if (TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+    if (TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
         .checkMockMessageHandler(
             SystemChannels.accessibility.name, _announcementHandler)) {
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
           .setMockDecodedMessageHandler(SystemChannels.accessibility, null);
       _announcementHandler = null;
     }

packages/flutter_test/lib/src/deprecated.dart

@@ -27,7 +27,7 @@ extension TestBinaryMessengerExtension on BinaryMessenger {
   //   'This feature was deprecated after v2.1.0-10.0.pre.'
   // )
   void setMockMessageHandler(String channel, MessageHandler? handler) {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMessageHandler(channel, handler);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMessageHandler(channel, handler);
   }
 
   /// Shim for `TestDefaultBinaryMessenger.checkMockMessageHandler`.
@@ -38,7 +38,7 @@ extension TestBinaryMessengerExtension on BinaryMessenger {
   //   'This feature was deprecated after v2.1.0-10.0.pre.'
   // )
   bool checkMockMessageHandler(String channel, Object? handler) {
-    return TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.checkMockMessageHandler(channel, handler);
+    return TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.checkMockMessageHandler(channel, handler);
   }
 }
 
@@ -59,7 +59,7 @@ extension TestBasicMessageChannelExtension<T> on BasicMessageChannel<T> {
   //   'This feature was deprecated after v2.1.0-10.0.pre.'
   // )
   void setMockMessageHandler(Future<T> Function(T? message)? handler) {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockDecodedMessageHandler<T>(this, handler);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockDecodedMessageHandler<T>(this, handler);
   }
 
   /// Shim for `TestDefaultBinaryMessenger.checkMockMessageHandler`.
@@ -71,7 +71,7 @@ extension TestBasicMessageChannelExtension<T> on BasicMessageChannel<T> {
   //   'This feature was deprecated after v2.1.0-10.0.pre.'
   // )
   bool checkMockMessageHandler(Object? handler) {
-    return TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.checkMockMessageHandler(name, handler);
+    return TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.checkMockMessageHandler(name, handler);
   }
 }
 
@@ -92,7 +92,7 @@ extension TestMethodChannelExtension on MethodChannel {
   //   'This feature was deprecated after v2.1.0-10.0.pre.'
   // )
   void setMockMethodCallHandler(Future<dynamic>? Function(MethodCall call)? handler) {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.setMockMethodCallHandler(this, handler);
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.setMockMethodCallHandler(this, handler);
   }
 
   /// Shim for `TestDefaultBinaryMessenger.checkMockMessageHandler`.
@@ -104,6 +104,6 @@ extension TestMethodChannelExtension on MethodChannel {
   //   'This feature was deprecated after v2.1.0-10.0.pre.'
   // )
   bool checkMockMethodCallHandler(Object? handler) {
-    return TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.checkMockMessageHandler(name, handler);
+    return TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.checkMockMessageHandler(name, handler);
   }
 }

packages/flutter_test/lib/src/event_simulation.dart

@@ -680,7 +680,7 @@ class KeyEventSimulator {
   static Future<bool> _simulateKeyEventByRawEvent(ValueGetter<Map<String, dynamic>> buildKeyData) async {
     return TestAsyncUtils.guard<bool>(() async {
       final Completer<bool> result = Completer<bool>();
-      await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.keyEvent.name,
         SystemChannels.keyEvent.codec.encodeMessage(buildKeyData()),
         (ByteData? data) {

packages/flutter_test/lib/src/test_text_input.dart

@@ -205,7 +205,7 @@ class TestTextInput {
   ///  * [enterText], which is similar but takes only a String and resets the
   ///    selection.
   void updateEditingValue(TextEditingValue value) {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
       SystemChannels.textInput.name,
       SystemChannels.textInput.codec.encodeMethodCall(
         MethodCall(
@@ -229,7 +229,7 @@ class TestTextInput {
   Future<void> receiveAction(TextInputAction action) async {
     return TestAsyncUtils.guard(() {
       final Completer<void> completer = Completer<void>();
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
         SystemChannels.textInput.name,
         SystemChannels.textInput.codec.encodeMethodCall(
           MethodCall(
@@ -269,7 +269,7 @@ class TestTextInput {
   /// example when using the [integration_test] library, there is a risk that
   /// the real IME will become confused as to the current state of input.
   void closeConnection() {
-    TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+    TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
       SystemChannels.textInput.name,
       SystemChannels.textInput.codec.encodeMethodCall(
         MethodCall(
@@ -284,7 +284,7 @@ class TestTextInput {
   /// Simulates a scribble interaction starting.
   Future<void> startScribbleInteraction() async {
     assert(isRegistered);
-    await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+    await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
       SystemChannels.textInput.name,
       SystemChannels.textInput.codec.encodeMethodCall(
         MethodCall(
@@ -299,7 +299,7 @@ class TestTextInput {
   /// Simulates a Scribble focus.
   Future<void> scribbleFocusElement(String elementIdentifier, Offset offset) async {
     assert(isRegistered);
-    await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+    await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
       SystemChannels.textInput.name,
       SystemChannels.textInput.codec.encodeMethodCall(
         MethodCall(
@@ -315,7 +315,7 @@ class TestTextInput {
   Future<List<List<dynamic>>> scribbleRequestElementsInRect(Rect rect) async {
     assert(isRegistered);
     List<List<dynamic>> response = <List<dynamic>>[];
-    await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+    await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
       SystemChannels.textInput.name,
       SystemChannels.textInput.codec.encodeMethodCall(
         MethodCall(
@@ -334,7 +334,7 @@ class TestTextInput {
   /// Simulates iOS inserting a UITextPlaceholder during a long press with the pencil.
   Future<void> scribbleInsertPlaceholder() async {
     assert(isRegistered);
-    await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+    await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
       SystemChannels.textInput.name,
       SystemChannels.textInput.codec.encodeMethodCall(
         MethodCall(
@@ -349,7 +349,7 @@ class TestTextInput {
   /// Simulates iOS removing a UITextPlaceholder after a long press with the pencil is released.
   Future<void> scribbleRemovePlaceholder() async {
     assert(isRegistered);
-    await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger.handlePlatformMessage(
+    await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger.handlePlatformMessage(
       SystemChannels.textInput.name,
       SystemChannels.textInput.codec.encodeMethodCall(
         MethodCall(

packages/flutter_test/lib/src/test_text_input_key_handler.dart

@@ -26,7 +26,7 @@ class MacOSTestTextInputKeyHandler extends TestTextInputKeyHandler {
   final int client;
 
   Future<void> _sendSelectors(List<String> selectors) async {
-    await TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+    await TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
         .handlePlatformMessage(
       SystemChannels.textInput.name,
       SystemChannels.textInput.codec.encodeMethodCall(

packages/flutter_test/test/widget_tester_test.dart

@@ -827,7 +827,7 @@ void main() {
     testWidgets('Returns the list of announcements', (WidgetTester tester) async {
 
       // Make sure the handler is properly set
-      expect(TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+      expect(TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
         .checkMockMessageHandler(SystemChannels.accessibility.name, null), isFalse);
 
       await SemanticsService.announce('announcement 1', TextDirection.ltr);
@@ -863,7 +863,7 @@ void main() {
         log.add(message);
       }
 
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
           .setMockDecodedMessageHandler<dynamic>(
               SystemChannels.accessibility, handleMessage);
 
@@ -883,14 +883,14 @@ void main() {
       ]));
 
       // Remove the handler
-      TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+      TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
           .setMockDecodedMessageHandler<dynamic>(
               SystemChannels.accessibility, null);
     });
 
     tearDown(() {
       // Make sure that the handler is removed in [TestWidgetsFlutterBinding.postTest]
-      expect(TestDefaultBinaryMessengerBinding.instance!.defaultBinaryMessenger
+      expect(TestDefaultBinaryMessengerBinding.instance.defaultBinaryMessenger
         .checkMockMessageHandler(SystemChannels.accessibility.name, null), isTrue);
     });
   });