mirror modifications from node core pr #40433 (#3)

index.js

@@ -57,15 +57,17 @@ class ActiveChannel {
 
   unsubscribe(subscription) {
     const index = this._subscribers.indexOf(subscription);
-    if (index >= 0) {
-      this._subscribers.splice(index, 1);
+    if (index === -1) return false;
 
-      // When there are no more active subscribers, restore to fast prototype.
-      if (!this._subscribers.length) {
-        // eslint-disable-next-line no-use-before-define
-        Object.setPrototypeOf(this, Channel.prototype);
-      }
+    this._subscribers.splice(index, 1);
+
+    // When there are no more active subscribers, restore to fast prototype.
+    if (!this._subscribers.length) {
+      // eslint-disable-next-line no-use-before-define
+      Object.setPrototypeOf(this, Channel.prototype);
     }
+
+    return true;
   }
 
   get hasSubscribers() {
@@ -104,6 +106,10 @@ class Channel {
     this.subscribe(subscription);
   }
 
+  unsubscribe() {
+    return false;
+  }
+
   get hasSubscribers() {
     return false;
   }

test/core/test-diagnostics-channel-object-channel-pub-sub.js

@@ -35,9 +35,12 @@ assert.ok(channel instanceof Channel);
 channel.publish(input);
 
 // Should not publish after subscriber is unsubscribed
-channel.unsubscribe(subscriber);
+assert.ok(channel.unsubscribe(subscriber));
 assert.ok(!channel.hasSubscribers);
 
+// unsubscribe() should return false when subscriber is not found
+assert.ok(!channel.unsubscribe(subscriber));
+
 assert.throws(() => {
   channel.subscribe(null);
 }, { code: 'ERR_INVALID_ARG_TYPE' });