prevent constant to be duplicated during tests

framework/core/src/Queue/QueueServiceProvider.php

@@ -36,7 +36,9 @@ class QueueServiceProvider extends AbstractServiceProvider
 
     public function register()
     {
+        if (! defined('ARTISAN_BINARY')) {
             define('ARTISAN_BINARY', 'flarum');
+        }
 
         // Register a simple connection factory that always returns the same
         // connection, as that is enough for our purposes.