Update for Flutter 3.10 beta (#1746)

## Pre-launch Checklist

- [x] I read the [Flutter Style Guide] _recently_, and have followed its
advice.
- [x] I signed the [CLA].
- [x] I read the [Contributors Guide].
- [x] I updated/added relevant documentation (doc comments with `///`).
- [ ] All existing and new tests are passing.

---------

Co-authored-by: David Iglesias <ditman@gmail.com>
Co-authored-by: Mark Thompson <2554588+MarkTechson@users.noreply.github.com>
Co-authored-by: John Ryan <ryjohn@google.com>

platform_channels/lib/src/event_channel_demo.dart

@@ -27,32 +27,22 @@ class EventChannelDemo extends StatelessWidget {
         child: StreamBuilder<AccelerometerReadings>(
           stream: Accelerometer.readings,
           builder: (context, snapshot) {
-            if (snapshot.hasError) {
-              return Text((snapshot.error as PlatformException).message!);
-            } else if (snapshot.hasData) {
-              return Column(
-                mainAxisAlignment: MainAxisAlignment.center,
-                children: [
-                  Text(
-                    'x axis: ${snapshot.data!.x.toStringAsFixed(3)}',
-                    style: textStyle,
-                  ),
-                  Text(
-                    'y axis: ${snapshot.data!.y.toStringAsFixed(3)}',
-                    style: textStyle,
-                  ),
-                  Text(
-                    'z axis: ${snapshot.data!.z.toStringAsFixed(3)}',
-                    style: textStyle,
-                  )
-                ],
-              );
-            }
-
-            return Text(
-              'No Data Available',
-              style: textStyle,
-            );
+            return switch (snapshot) {
+              AsyncSnapshot(hasError: true) =>
+                Text((snapshot.error as PlatformException).message!),
+              AsyncSnapshot(hasData: true) => Column(
+                  mainAxisAlignment: MainAxisAlignment.center,
+                  children: [
+                    Text('x axis: ${snapshot.data!.x.toStringAsFixed(3)}',
+                        style: textStyle),
+                    Text('y axis: ${snapshot.data!.y.toStringAsFixed(3)}',
+                        style: textStyle),
+                    Text('z axis: ${snapshot.data!.z.toStringAsFixed(3)}',
+                        style: textStyle)
+                  ],
+                ),
+              _ => Text('No Data Available', style: textStyle),
+            };
           },
         ),
       ),

platform_channels/pubspec.yaml

@@ -4,7 +4,7 @@ description: A new Flutter project.
 version: 1.0.0+1
 
 environment:
-  sdk: '>=2.19.5 <4.0.0'
+  sdk: ^3.0.0-0
 
 dependencies:
   flutter:

platform_channels/test/src/add_pet_details_test.dart

@@ -11,15 +11,14 @@ void main() {
   group('AddPetDetails tests', () {
     var petList = <Map>[];
 
-    setUpAll(() {
-      const BasicMessageChannel<dynamic>(
-              'jsonMessageCodecDemo', JSONMessageCodec())
-          .setMockMessageHandler((dynamic message) async {
-        petList.add(message as Map);
-      });
-    });
-
     testWidgets('Enter pet details', (tester) async {
+      tester.binding.defaultBinaryMessenger.setMockDecodedMessageHandler(
+        const BasicMessageChannel<dynamic>(
+            'jsonMessageCodecDemo', JSONMessageCodec()),
+        (dynamic message) async {
+          petList.add(message as Map);
+        },
+      );
       var router = app.router('/petListScreen/addPetDetails');
       await tester.pumpWidget(
         MaterialApp.router(

platform_channels/test/src/method_channel_demo_test.dart

@@ -9,23 +9,20 @@ import 'package:platform_channels/src/method_channel_demo.dart';
 
 void main() {
   group('MethodChannelDemo tests', () {
-    setUpAll(() {
-      const methodChannel = MethodChannel('methodChannelDemo');
-
-      // Register a mock MethodCallHandler.
-      methodChannel.setMockMethodCallHandler((call) async {
-        var count = call.arguments['count'] as int;
-        if (call.method == 'increment') {
-          return ++count;
-        } else if (call.method == 'decrement') {
-          return --count;
-        }
-
-        return MissingPluginException();
-      });
-    });
-
     testWidgets('MethodChannelDemo count test', (tester) async {
+      tester.binding.defaultBinaryMessenger.setMockMethodCallHandler(
+        const MethodChannel('methodChannelDemo'),
+        (call) async {
+          var count = call.arguments['count'] as int;
+          if (call.method == 'increment') {
+            return ++count;
+          } else if (call.method == 'decrement') {
+            return --count;
+          }
+
+          return MissingPluginException();
+        },
+      );
       await tester.pumpWidget(const MaterialApp(
         home: MethodChannelDemo(),
       ));

platform_channels/test/src/platform_image_demo_test.dart

@@ -9,17 +9,15 @@ import 'package:platform_channels/src/platform_image_demo.dart';
 
 void main() {
   group('Platform Image Demo tests', () {
-    setUpAll(() {
-      // Register a mock for MessageHandler.
-      const BasicMessageChannel<dynamic>(
-              'platformImageDemo', StandardMessageCodec())
-          .setMockMessageHandler((dynamic message) async {
-        var byteData = await rootBundle.load('assets/eat_new_orleans.jpg');
-        return byteData.buffer.asUint8List();
-      });
-    });
-
     testWidgets('Platform Image test', (tester) async {
+      tester.binding.defaultBinaryMessenger.setMockDecodedMessageHandler(
+        const BasicMessageChannel<dynamic>(
+            'platformImageDemo', StandardMessageCodec()),
+        (dynamic message) async {
+          var byteData = await rootBundle.load('assets/eat_new_orleans.jpg');
+          return byteData.buffer.asUint8List();
+        },
+      );
       await tester.pumpWidget(const MaterialApp(
         home: PlatformImageDemo(),
       ));