[Messenger] Allow handler locator to be set

maxbaldanza · maxbaldanza · commit fcff4aed2e5b · 2025-06-10T15:51:34.000+01:00
The `HandleMessageMiddleware` has a dependency on a `HandlersLocatorInterface`
but this gets registered by the messenger pass.

As far as I can see there isn't a way for an application to provide it's
own implementation. By checking if the service already exists before
registering then we can allow applications to define their own
diff --git a/src/Symfony/Component/Messenger/DependencyInjection/MessengerPass.php b/src/Symfony/Component/Messenger/DependencyInjection/MessengerPass.php
@@ -165,9 +165,13 @@ private function registerHandlers(ContainerBuilder $container, array $busIds): v
         $container->addDefinitions($definitions);
 
         foreach ($busIds as $bus) {
-            $container->register($locatorId = $bus.'.messenger.handlers_locator', HandlersLocator::class)
-                ->setArgument(0, $handlersLocatorMappingByBus[$bus] ?? [])
-            ;
+            $locatorId = $bus.'.messenger.handlers_locator';
+            if (!$container->has($locatorId)) {
+                $container->register($locatorId, HandlersLocator::class)
+                    ->setArgument(0, $handlersLocatorMappingByBus[$bus] ?? [])
+                ;
+            }
+
             if ($container->has($handleMessageId = $bus.'.middleware.handle_message')) {
                 $container->getDefinition($handleMessageId)
                     ->replaceArgument(0, new Reference($locatorId))
diff --git a/src/Symfony/Component/Messenger/Tests/DependencyInjection/MessengerPassTest.php b/src/Symfony/Component/Messenger/Tests/DependencyInjection/MessengerPassTest.php
@@ -809,6 +809,17 @@ public function testItRegistersTheDebugCommand()
         ], $container->getDefinition('console.command.messenger_debug')->getArgument(0));
     }
 
+    public function testCanOverrideHandlersLocator()
+    {
+        $container = $this->getContainerBuilder($busId = 'message_bus');
+
+        $container->register($busId. '.messenger.handlers_locator', \stdClass::class);
+
+        (new MessengerPass())->process($container);
+
+        $this->assertSame(\stdClass::class, $container->getDefinition($busId. '.messenger.handlers_locator')->getClass());
+    }
+
     private function getContainerBuilder(string $busId = 'message_bus'): ContainerBuilder
     {
         $container = new ContainerBuilder();
