From 58a0e7e036a2f914343d146ac78909f9cb3b163e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Rub=C3=A9n=20Norte?= <rubennorte@meta.com>
Date: Mon, 6 Jan 2025 07:20:07 -0800
Subject: [PATCH] [skip ci] Add regression test for EventTarget (#48431)

Summary:

Changelog: [internal]

Adds a regression test to make sure we implement the correct spec-compliant behavior for a possible bug in ~~the Web spec~~ __Chrome__: https://github.com/whatwg/dom/issues/1346

Edit: the bug is in the Chrome implementation, not in the spec.

Differential Revision: D67758702
---
 .../private/webapis/dom/events/EventTarget.js | 25 +++++++---
 .../dom/events/__tests__/EventTarget-itest.js | 48 +++++++++++++++++++
 2 files changed, 67 insertions(+), 6 deletions(-)

diff --git a/packages/react-native/src/private/webapis/dom/events/EventTarget.js b/packages/react-native/src/private/webapis/dom/events/EventTarget.js
index 8d4e8bc9bd3e67..1e394ab99b5f7f 100644
--- a/packages/react-native/src/private/webapis/dom/events/EventTarget.js
+++ b/packages/react-native/src/private/webapis/dom/events/EventTarget.js
@@ -127,16 +127,17 @@ export default class EventTarget {
       }
     }
 
-    listenerList.push({
+    const listener: EventListenerRegistration = {
       callback,
       passive,
       once,
       removed: false,
-    });
+    };
+    listenerList.push(listener);
 
     if (signal != null) {
       signal.addEventListener('abort', () => {
-        this.removeEventListener(processedType, callback, capture);
+        this.#removeEventListenerRegistration(listener, listenerList);
       });
     }
   }
@@ -180,9 +181,6 @@ export default class EventTarget {
         return;
       }
     }
-
-    // NOTE: there is no step to remove the event listener from the signal, if
-    // set, as per the spec. See https://github.com/whatwg/dom/issues/1346.
   }
 
   dispatchEvent(event: Event): boolean {
@@ -344,6 +342,21 @@ export default class EventTarget {
     }
   }
 
+  #removeEventListenerRegistration(
+    registration: EventListenerRegistration,
+    listenerList: Array<EventListenerRegistration>,
+  ): void {
+    for (let i = 0; i < listenerList.length; i++) {
+      const listener = listenerList[i];
+
+      if (listener === registration) {
+        listener.removed = true;
+        listenerList.splice(i, 1);
+        return;
+      }
+    }
+  }
+
   /**
    * This a "protected" method to be overridden by a subclass to allow event
    * propagation.
diff --git a/packages/react-native/src/private/webapis/dom/events/__tests__/EventTarget-itest.js b/packages/react-native/src/private/webapis/dom/events/__tests__/EventTarget-itest.js
index 6d82f51e6890d3..43dbc6d668b2d4 100644
--- a/packages/react-native/src/private/webapis/dom/events/__tests__/EventTarget-itest.js
+++ b/packages/react-native/src/private/webapis/dom/events/__tests__/EventTarget-itest.js
@@ -926,5 +926,53 @@ describe('EventTarget', () => {
         expect(listenerThatWillBeRemoved).not.toHaveBeenCalled();
       });
     });
+
+    describe('re-attaching a previous listener with a pending signal', () => {
+      // This is a regression test for https://github.com/whatwg/dom/issues/1346
+      it('should NOT remove the new subscription when the signal for the old subscription is aborted', () => {
+        const [node] = createEventTargetHierarchyWithDepth(1);
+
+        // Listener setup
+
+        resetListenerCallOrder();
+
+        const listener = createListener();
+
+        const abortController = new AbortController();
+
+        node.addEventListener('custom', listener, {
+          signal: abortController.signal,
+        });
+
+        // Dispatch
+
+        const event = new Event('custom');
+
+        node.dispatchEvent(event);
+
+        expect(listener).toHaveBeenCalledTimes(1);
+
+        node.removeEventListener('custom', listener);
+
+        node.dispatchEvent(event);
+
+        expect(listener).toHaveBeenCalledTimes(1);
+
+        // Added without a signal
+        node.addEventListener('custom', listener);
+
+        node.dispatchEvent(event);
+
+        // Listener is called
+        expect(listener).toHaveBeenCalledTimes(2);
+
+        abortController.abort();
+
+        node.dispatchEvent(event);
+
+        // Listener is called
+        expect(listener).toHaveBeenCalledTimes(3);
+      });
+    });
   });
 });