[pigeon] fixes event channel dart instance name usage and adds test (#8483)

fixes event channel dart instance name usage and adds test
fixes flutter/flutter#161813

Author: tarrinneal

packages/pigeon/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 22.7.4
+
+* [dart] Fixes bug with multi-instance event channel support.
+
 ## 22.7.3
 
 * Adds compatibility with `analyzer` 7.x.*.

packages/pigeon/example/app/lib/src/event_channel_messages.g.dart

@@ -93,8 +93,8 @@ Stream<PlatformEvent> streamEvents({String instanceName = ''}) {
   if (instanceName.isNotEmpty) {
     instanceName = '.$instanceName';
   }
-  const EventChannel streamEventsChannel = EventChannel(
-      'dev.flutter.pigeon.pigeon_example_package.EventChannelMethods.streamEvents',
+  final EventChannel streamEventsChannel = EventChannel(
+      'dev.flutter.pigeon.pigeon_example_package.EventChannelMethods.streamEvents$instanceName',
       pigeonMethodCodec);
   return streamEventsChannel.receiveBroadcastStream().map((dynamic event) {
     return event as PlatformEvent;

packages/pigeon/lib/dart_generator.dart

@@ -556,8 +556,8 @@ final BinaryMessenger? ${varNamePrefix}binaryMessenger;
         if (instanceName.isNotEmpty) {
           instanceName = '.\$instanceName';
         }
-        const EventChannel ${func.name}Channel =
-            EventChannel('${makeChannelName(api, func, dartPackageName)}', $_pigeonMethodChannelCodec);
+        final EventChannel ${func.name}Channel =
+            EventChannel('${makeChannelName(api, func, dartPackageName)}\$instanceName', $_pigeonMethodChannelCodec);
         return ${func.name}Channel.receiveBroadcastStream().map((dynamic event) {
           return event as ${func.returnType.baseName};
         });

packages/pigeon/lib/generator_tools.dart

@@ -14,7 +14,7 @@ import 'ast.dart';
 /// The current version of pigeon.
 ///
 /// This must match the version in pubspec.yaml.
-const String pigeonVersion = '22.7.3';
+const String pigeonVersion = '22.7.4';
 
 /// Read all the content from [stdin] to a String.
 String readStdin() {

packages/pigeon/pigeons/event_channel_tests.dart

@@ -141,4 +141,5 @@ class ClassEvent extends PlatformEvent {
 abstract class EventChannelMethods {
   int streamInts();
   PlatformEvent streamEvents();
+  int streamConsistentNumbers();
 }

packages/pigeon/platform_tests/shared_test_plugin_code/lib/integration_tests.dart

@@ -2865,6 +2865,7 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
     TargetGenerator.kotlin,
     TargetGenerator.swift
   ];
+
   testWidgets('event channel sends continuous ints', (_) async {
     final Stream<int> events = streamInts();
     final List<int> listEvents = await events.toList();
@@ -2912,6 +2913,24 @@ void runPigeonIntegrationTests(TargetGenerator targetGenerator) {
     });
     await completer.future;
   }, skip: !eventChannelSupported.contains(targetGenerator));
+
+  testWidgets('event channels handle multiple instances', (_) async {
+    final Completer<void> completer1 = Completer<void>();
+    final Completer<void> completer2 = Completer<void>();
+    final Stream<int> events1 = streamConsistentNumbers(instanceName: '1');
+    final Stream<int> events2 = streamConsistentNumbers(instanceName: '2');
+
+    events1.listen((int event) {
+      expect(event, 1);
+    }).onDone(() => completer1.complete());
+
+    events2.listen((int event) {
+      expect(event, 2);
+    }).onDone(() => completer2.complete());
+
+    await completer1.future;
+    await completer2.future;
+  }, skip: !eventChannelSupported.contains(targetGenerator));
 }
 
 class _FlutterApiTestImplementation implements FlutterIntegrationCoreApi {

packages/pigeon/platform_tests/shared_test_plugin_code/lib/src/generated/event_channel_tests.gen.dart

@@ -432,8 +432,8 @@ Stream<int> streamInts({String instanceName = ''}) {
   if (instanceName.isNotEmpty) {
     instanceName = '.$instanceName';
   }
-  const EventChannel streamIntsChannel = EventChannel(
-      'dev.flutter.pigeon.pigeon_integration_tests.EventChannelMethods.streamInts',
+  final EventChannel streamIntsChannel = EventChannel(
+      'dev.flutter.pigeon.pigeon_integration_tests.EventChannelMethods.streamInts$instanceName',
       pigeonMethodCodec);
   return streamIntsChannel.receiveBroadcastStream().map((dynamic event) {
     return event as int;
@@ -444,10 +444,24 @@ Stream<PlatformEvent> streamEvents({String instanceName = ''}) {
   if (instanceName.isNotEmpty) {
     instanceName = '.$instanceName';
   }
-  const EventChannel streamEventsChannel = EventChannel(
-      'dev.flutter.pigeon.pigeon_integration_tests.EventChannelMethods.streamEvents',
+  final EventChannel streamEventsChannel = EventChannel(
+      'dev.flutter.pigeon.pigeon_integration_tests.EventChannelMethods.streamEvents$instanceName',
       pigeonMethodCodec);
   return streamEventsChannel.receiveBroadcastStream().map((dynamic event) {
     return event as PlatformEvent;
   });
 }
+
+Stream<int> streamConsistentNumbers({String instanceName = ''}) {
+  if (instanceName.isNotEmpty) {
+    instanceName = '.$instanceName';
+  }
+  final EventChannel streamConsistentNumbersChannel = EventChannel(
+      'dev.flutter.pigeon.pigeon_integration_tests.EventChannelMethods.streamConsistentNumbers$instanceName',
+      pigeonMethodCodec);
+  return streamConsistentNumbersChannel
+      .receiveBroadcastStream()
+      .map((dynamic event) {
+    return event as int;
+  });
+}

packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/EventChannelTests.gen.kt

@@ -470,3 +470,22 @@ abstract class StreamEventsStreamHandler : PigeonEventChannelWrapper<PlatformEve
     }
   }
 }
+
+abstract class StreamConsistentNumbersStreamHandler : PigeonEventChannelWrapper<Long> {
+  companion object {
+    fun register(
+        messenger: BinaryMessenger,
+        streamHandler: StreamConsistentNumbersStreamHandler,
+        instanceName: String = ""
+    ) {
+      var channelName: String =
+          "dev.flutter.pigeon.pigeon_integration_tests.EventChannelMethods.streamConsistentNumbers"
+      if (instanceName.isNotEmpty()) {
+        channelName += ".$instanceName"
+      }
+      val internalStreamHandler = PigeonStreamHandler<Long>(streamHandler)
+      EventChannel(messenger, channelName, EventChannelTestsPigeonMethodCodec)
+          .setStreamHandler(internalStreamHandler)
+    }
+  }
+}

packages/pigeon/platform_tests/test_plugin/android/src/main/kotlin/com/example/test_plugin/TestPlugin.kt

@@ -31,6 +31,10 @@ class TestPlugin : FlutterPlugin, HostIntegrationCoreApi {
 
     StreamEventsStreamHandler.register(binding.binaryMessenger, SendClass)
     StreamIntsStreamHandler.register(binding.binaryMessenger, SendInts)
+    StreamConsistentNumbersStreamHandler.register(
+        binding.binaryMessenger, SendConsistentNumbers(1), "1")
+    StreamConsistentNumbersStreamHandler.register(
+        binding.binaryMessenger, SendConsistentNumbers(2), "2")
   }
 
   override fun onDetachedFromEngine(binding: FlutterPlugin.FlutterPluginBinding) {
@@ -927,3 +931,27 @@ object SendClass : StreamEventsStreamHandler() {
     handler.postDelayed(r, 10)
   }
 }
+
+class SendConsistentNumbers(private val numberToSend: Long) :
+    StreamConsistentNumbersStreamHandler() {
+  private val handler = Handler(Looper.getMainLooper())
+
+  override fun onListen(p0: Any?, sink: PigeonEventSink<Long>) {
+    var count: Int = 0
+    val r: Runnable =
+        object : Runnable {
+          override fun run() {
+            if (count >= 10) {
+              sink.endOfStream()
+            } else {
+              handler.post {
+                sink.success(numberToSend)
+                count++
+              }
+              handler.postDelayed(this, 10)
+            }
+          }
+        }
+    handler.postDelayed(r, 10)
+  }
+}

packages/pigeon/platform_tests/test_plugin/ios/Classes/EventChannelTests.gen.swift

@@ -574,3 +574,21 @@ class StreamEventsStreamHandler: PigeonEventChannelWrapper<PlatformEvent> {
     channel.setStreamHandler(internalStreamHandler)
   }
 }
+
+class StreamConsistentNumbersStreamHandler: PigeonEventChannelWrapper<Int64> {
+  static func register(
+    with messenger: FlutterBinaryMessenger,
+    instanceName: String = "",
+    streamHandler: StreamConsistentNumbersStreamHandler
+  ) {
+    var channelName =
+      "dev.flutter.pigeon.pigeon_integration_tests.EventChannelMethods.streamConsistentNumbers"
+    if !instanceName.isEmpty {
+      channelName += ".\(instanceName)"
+    }
+    let internalStreamHandler = PigeonStreamHandler<Int64>(wrapper: streamHandler)
+    let channel = FlutterEventChannel(
+      name: channelName, binaryMessenger: messenger, codec: eventChannelTestsPigeonMethodCodec)
+    channel.setStreamHandler(internalStreamHandler)
+  }
+}