From 7ba4a43adf554c3c92ff74ae960466dca76066a1 Mon Sep 17 00:00:00 2001
From: Kk Shinkai <i@shinkai.moe>
Date: Wed, 2 Oct 2024 01:40:10 +0800
Subject: [PATCH 1/2] Correctly trigger the `onDidAddListener` event in emitter
 options

---
 src/vs/base/common/event.ts | 1 +
 1 file changed, 1 insertion(+)

diff --git a/src/vs/base/common/event.ts b/src/vs/base/common/event.ts
index 33c834929c02..f369e8adccbb 100644
--- a/src/vs/base/common/event.ts
+++ b/src/vs/base/common/event.ts
@@ -1155,6 +1155,7 @@ export class Emitter<T> {
 			} else {
 				this._listeners.push(contained);
 			}
+			this._options?.onDidAddListener?.(this);
 
 			this._size++;
 

From 2e48a0fe05e3a8970750e8ac67f9e57ad1b86311 Mon Sep 17 00:00:00 2001
From: Kk Shinkai <i@shinkai.moe>
Date: Thu, 3 Oct 2024 14:20:35 +0800
Subject: [PATCH 2/2] Add test for `Emitter.onDidAddListener`

---
 src/vs/base/test/common/event.test.ts | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/src/vs/base/test/common/event.test.ts b/src/vs/base/test/common/event.test.ts
index 9f08b1441338..476f0ca375c4 100644
--- a/src/vs/base/test/common/event.test.ts
+++ b/src/vs/base/test/common/event.test.ts
@@ -308,6 +308,27 @@ suite('Event', function () {
 		assert.strictEqual(lastCount, 1);
 	});
 
+	test('onDidAddListener', () => {
+		let count = 0;
+		const a = ds.add(new Emitter({
+			onDidAddListener() { count += 1; }
+		}));
+
+		assert.strictEqual(count, 0);
+
+		let subscription = ds.add(a.event(function () { }));
+		assert.strictEqual(count, 1);
+
+		subscription.dispose();
+		assert.strictEqual(count, 1);
+
+		subscription = ds.add(a.event(function () { }));
+		assert.strictEqual(count, 2);
+
+		subscription.dispose();
+		assert.strictEqual(count, 2);
+	});
+
 	test('onWillRemoveListener', () => {
 		let count = 0;
 		const a = ds.add(new Emitter({