Displays friendly message if the event does not have any registered listeners

Matthieu Auger · matthieuauger · commit 8bb93020449f · 2015-02-23T10:54:08.000+01:00
diff --git a/src/Symfony/Bundle/FrameworkBundle/Command/EventDispatcherDebugCommand.php b/src/Symfony/Bundle/FrameworkBundle/Command/EventDispatcherDebugCommand.php
@@ -58,14 +58,28 @@ protected function configure()
      */
     protected function execute(InputInterface $input, OutputInterface $output)
     {
+        $dispatcher = $this->getEventDispatcher();
+
         if ($event = $input->getArgument('event')) {
+            if (!$dispatcher->hasListeners($event)) {
+                $formatter = $this->getHelperSet()->get('formatter');
+
+                $formattedBlock = $formatter->formatBlock(
+                    sprintf('[NOTE] The event "%s" does not have any registered listeners.', $event),
+                    'fg=yellow',
+                    true
+                );
+
+                $output->writeln($formattedBlock);
+
+                return;
+            }
+
             $options = array('event' => $event);
         } else {
             $options = array();
         }
 
-        $dispatcher = $this->getEventDispatcher();
-
         $helper = new DescriptorHelper();
         $options['format'] = $input->getOption('format');
         $options['raw_text'] = $input->getOption('raw');
