From 030ca3c54301bd35c8060dc386fa5f76eb16fcef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rub=C3=A9n=20Norte?= <rubennorte@meta.com>
Date: Tue, 29 Apr 2025 10:13:09 -0700
Subject: [PATCH] Fix bug when dispatching unique and non-unique events of the
 same type on the same target (#50988)

Summary:
Pull Request resolved: https://github.com/facebook/react-native/pull/50988

Changelog: [internal]

This fixes a potential bug where we coalesce unique events with non-unique ones of the same type and target.

Not marked as a bug fix in the changelog because this wouldn't happen in practice, as we always dispatch events of a given type the same way (all unique or all non-unique).

Reviewed By: sammy-SC, javache

Differential Revision: D73849222

fbshipit-source-id: 6f387d63b3a68dccc81c110287d42e15e31c181e
---
 .../src/__tests__/Fantom-itest.js               | 17 ++++++++++++-----
 .../ScrollView/__tests__/ScrollView-itest.js    | 17 ++++++++++++-----
 .../react/renderer/core/EventQueue.cpp          |  2 +-
 .../core/__tests__/EventDispatching-itest.js    |  2 +-
 4 files changed, 26 insertions(+), 12 deletions(-)

diff --git a/packages/react-native-fantom/src/__tests__/Fantom-itest.js b/packages/react-native-fantom/src/__tests__/Fantom-itest.js
index a30c058464d..d58ebd15043 100644
--- a/packages/react-native-fantom/src/__tests__/Fantom-itest.js
+++ b/packages/react-native-fantom/src/__tests__/Fantom-itest.js
@@ -497,12 +497,19 @@ describe('Fantom', () => {
       const element = ensureInstance(ref.current, ReactNativeElement);
 
       Fantom.runOnUIThread(() => {
-        Fantom.enqueueNativeEvent(element, 'scroll', {
-          contentOffset: {
-            x: 0,
-            y: 1,
+        Fantom.enqueueNativeEvent(
+          element,
+          'scroll',
+          {
+            contentOffset: {
+              x: 0,
+              y: 1,
+            },
           },
-        });
+          {
+            isUnique: true,
+          },
+        );
         Fantom.enqueueNativeEvent(
           element,
           'scroll',
diff --git a/packages/react-native/Libraries/Components/ScrollView/__tests__/ScrollView-itest.js b/packages/react-native/Libraries/Components/ScrollView/__tests__/ScrollView-itest.js
index fc14bd8e24d..a052de476c5 100644
--- a/packages/react-native/Libraries/Components/ScrollView/__tests__/ScrollView-itest.js
+++ b/packages/react-native/Libraries/Components/ScrollView/__tests__/ScrollView-itest.js
@@ -83,12 +83,19 @@ describe('onScroll', () => {
     const element = ensureInstance(scrollViewRef.current, ReactNativeElement);
 
     Fantom.runOnUIThread(() => {
-      Fantom.enqueueNativeEvent(element, 'scroll', {
-        contentOffset: {
-          x: 0,
-          y: 1,
+      Fantom.enqueueNativeEvent(
+        element,
+        'scroll',
+        {
+          contentOffset: {
+            x: 0,
+            y: 1,
+          },
         },
-      });
+        {
+          isUnique: true,
+        },
+      );
       Fantom.enqueueNativeEvent(
         element,
         'scroll',
diff --git a/packages/react-native/ReactCommon/react/renderer/core/EventQueue.cpp b/packages/react-native/ReactCommon/react/renderer/core/EventQueue.cpp
index 45e650b33df..defac2e416e 100644
--- a/packages/react-native/ReactCommon/react/renderer/core/EventQueue.cpp
+++ b/packages/react-native/ReactCommon/react/renderer/core/EventQueue.cpp
@@ -35,7 +35,7 @@ void EventQueue::enqueueEvent(RawEvent&& rawEvent) const {
 
       for (auto it = eventQueue_.rbegin(); it != eventQueue_.rend(); ++it) {
         if (it->type == rawEvent.type &&
-            it->eventTarget == rawEvent.eventTarget) {
+            it->eventTarget == rawEvent.eventTarget && it->isUnique) {
           repeatedEvent = it;
           break;
         } else if (it->eventTarget == rawEvent.eventTarget) {
diff --git a/packages/react-native/src/private/renderer/core/__tests__/EventDispatching-itest.js b/packages/react-native/src/private/renderer/core/__tests__/EventDispatching-itest.js
index bec84e358fc..bdcaf83bbc0 100644
--- a/packages/react-native/src/private/renderer/core/__tests__/EventDispatching-itest.js
+++ b/packages/react-native/src/private/renderer/core/__tests__/EventDispatching-itest.js
@@ -483,7 +483,7 @@ describe('Event Dispatching', () => {
       expect(onPointerMove).toHaveBeenCalledTimes(2);
     });
 
-    it.skip('are NOT combined with the same type if it is non-unique', () => {
+    it('are NOT combined with the same type if it is non-unique', () => {
       const root = Fantom.createRoot();
 
       const ref = React.createRef<React.ElementRef<typeof View>>();