Merge branch 'FME-11223-web-support-fix-onUpdated-with-async-callbacks' into FME-11223-web-support-js-interop-improvements

Author: EmilianoSanchez

splitio_web/lib/splitio_web.dart

@@ -741,6 +741,9 @@ class SplitioWeb extends SplitioPlatform {
     _factory.UserConsent.setStatus(enabled.toJS);
   }
 
+  // To ensure the public `onXXX` callbacks and `whenXXX` methods work correctly,
+  // the `onXXX` method implementations always return a Future or Stream that waits for the client to be initialized.
+
   @override
   Future<void>? onReady(
       {required String matchingKey, required String? bucketingKey}) async {
@@ -813,31 +816,37 @@ class SplitioWeb extends SplitioPlatform {
   @override
   Stream<void>? onUpdated(
       {required String matchingKey, required String? bucketingKey}) {
-    final client = _clients[buildKeyString(matchingKey, bucketingKey)];
-
-    if (client == null) {
-      return null;
-    }
+    // To ensure the public `onUpdated` callback and `whenUpdated` method work correctly,
+    // this method always return a stream, and the StreamController callbacks
+    // are async to wait for the client to be initialized.
 
     late final StreamController<void> controller;
     final JSFunction jsCallback = (() {
       if (!controller.isClosed) {
         controller.add(null);
       }
     }).toJS;
+    final registerJsCallback = () async {
+      final client = await _getClient(
+        matchingKey: matchingKey,
+        bucketingKey: bucketingKey,
+      );
+      client.on(client.Event.SDK_UPDATE, jsCallback);
+    };
+    final deregisterJsCallback = () async {
+      final client = await _getClient(
+        matchingKey: matchingKey,
+        bucketingKey: bucketingKey,
+      );
+      client.off(client.Event.SDK_UPDATE, jsCallback);
+    };
 
     controller = StreamController<void>(
-      onListen: () {
-        client.on(client.Event.SDK_UPDATE, jsCallback);
-      },
-      onPause: () {
-        client.off(client.Event.SDK_UPDATE, jsCallback);
-      },
-      onResume: () {
-        client.on(client.Event.SDK_UPDATE, jsCallback);
-      },
+      onListen: registerJsCallback,
+      onPause: deregisterJsCallback,
+      onResume: registerJsCallback,
       onCancel: () async {
-        client.off(client.Event.SDK_UPDATE, jsCallback);
+        await deregisterJsCallback();
         if (!controller.isClosed) {
           await controller.close();
         }

splitio_web/test/splitio_web_test.dart

@@ -1038,34 +1038,29 @@ void main() {
     });
 
     test('onUpdated', () async {
-      // Precondition: client is initialized before onUpdated is called
-      await _platform.getClient(
-          matchingKey: 'matching-key', bucketingKey: 'bucketing-key');
       final mockClient =
           mock.mockFactory.client(buildJsKey('matching-key', 'bucketing-key'));
 
       final stream = _platform.onUpdated(
           matchingKey: 'matching-key', bucketingKey: 'bucketing-key')!;
       final subscription = stream.listen(expectAsync1((_) {}, count: 3));
+      await Future<void>.delayed(Duration.zero); // onListen is async
 
       // Emit SDK_UPDATE events. Should be received
       mockClient.emit(mockClient.Event.SDK_UPDATE);
-
       mockClient.emit(mockClient.Event.SDK_UPDATE);
 
-      await Future<void>.delayed(
-          const Duration(milliseconds: 100)); // let events deliver
-
       // Pause subscription and emit SDK_UPDATE event. Should not be received
       subscription.pause();
+      await Future<void>.delayed(Duration.zero); // onPause is async
       mockClient.emit(mockClient.Event.SDK_UPDATE);
-      await Future<void>.delayed(const Duration(milliseconds: 100));
 
       // Resume subscription and emit SDK_UPDATE event. Should be received
       subscription.resume();
+      await Future<void>.delayed(Duration.zero); // onResume is async
       mockClient.emit(mockClient.Event.SDK_UPDATE);
-      await Future<void>.delayed(const Duration(milliseconds: 100));
 
+      await Future<void>.delayed(Duration.zero); // let last event deliver before cancel
       await subscription.cancel();
     });
   });