Test Action Cable action in Rails app

Make sure we add a scenario that actually triggers an Action Cable
action so that we can test if it's instrumented.

ruby/rails7-sidekiq/app/Gemfile.lock

@@ -1,7 +1,7 @@
 PATH
   remote: /integration
   specs:
-    appsignal (3.9.1)
+    appsignal (3.10.0)
       rack
 
 GEM

ruby/rails7-sidekiq/app/app/channels/chat_room_channel.rb

@@ -17,4 +17,12 @@ def echo(data)
     data.delete("action")
     transmit data
   end
+
+  def add_connected_message
+    message = ChatMessage.new(
+      :body => "You're connected to the chat room!",
+      :created_at => Time.zone.now,
+    )
+    transmit message
+  end
 end

ruby/rails7-sidekiq/app/app/javascript/channels/chat_room_channel.js

@@ -8,6 +8,9 @@ if (chatRoomId) {
   consumer.subscriptions.create({ channel: "ChatRoomChannel", chat_room_id: chatRoomId }, {
     connected() {
       console.log(`Subscribed to ${chatRoomId}`)
+      // You would do this from the channel itself, but this triggers an action
+      // in the Channel so that we can test if instrument the action.
+      this.perform("add_connected_message")
     },
 
     disconnected() {