Include identifier in ActionCable channel notifications (rails#52421)

Author: krschacht

actioncable/CHANGELOG.md

@@ -1,2 +1,5 @@
+*   Add an `identifier` to the event payload for the ActiveSupport::Notification `transmit_subscription_confirmation.action_cable` and `transmit_subscription_rejection.action_cable`.
+
+    *Keith Schacht*
 
 Please check [7-2-stable](https://github.com/rails/rails/blob/7-2-stable/actioncable/CHANGELOG.md) for previous changes.

actioncable/lib/action_cable/channel/base.rb

@@ -309,7 +309,7 @@ def transmit_subscription_confirmation
           unless subscription_confirmation_sent?
             logger.debug "#{self.class.name} is transmitting the subscription confirmation"
 
-            ActiveSupport::Notifications.instrument("transmit_subscription_confirmation.action_cable", channel_class: self.class.name) do
+            ActiveSupport::Notifications.instrument("transmit_subscription_confirmation.action_cable", channel_class: self.class.name, identifier: @identifier) do
               connection.transmit identifier: @identifier, type: ActionCable::INTERNAL[:message_types][:confirmation]
               @subscription_confirmation_sent = true
             end
@@ -324,7 +324,7 @@ def reject_subscription
         def transmit_subscription_rejection
           logger.debug "#{self.class.name} is transmitting the subscription rejection"
 
-          ActiveSupport::Notifications.instrument("transmit_subscription_rejection.action_cable", channel_class: self.class.name) do
+          ActiveSupport::Notifications.instrument("transmit_subscription_rejection.action_cable", channel_class: self.class.name, identifier: @identifier) do
             connection.transmit identifier: @identifier, type: ActionCable::INTERNAL[:message_types][:rejection]
           end
         end

actioncable/test/channel/base_test.rb

@@ -242,6 +242,7 @@ def error_handler
       assert_equal 1, events.length
       assert_equal "transmit_subscription_confirmation.action_cable", events[0].name
       assert_equal "ActionCable::Channel::BaseTest::ChatChannel", events[0].payload[:channel_class]
+      assert_equal "{id: 1}", events[0].payload[:identifier]
     end
   ensure
     ActiveSupport::Notifications.unsubscribe "transmit_subscription_confirmation.action_cable"
@@ -256,6 +257,7 @@ def error_handler
     assert_equal 1, events.length
     assert_equal "transmit_subscription_rejection.action_cable", events[0].name
     assert_equal "ActionCable::Channel::BaseTest::ChatChannel", events[0].payload[:channel_class]
+    assert_equal "{id: 1}", events[0].payload[:identifier]
   ensure
     ActiveSupport::Notifications.unsubscribe "transmit_subscription_rejection.action_cable"
   end