bug symfony#26896 Messenger: fix for interface_exists (weaverryan, sroze)

This PR was merged into the 4.1-dev branch.

Discussion
----------

Messenger: fix for interface_exists

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no->
| Tests pass?   | yes
| Fixed tickets | none
| License       | MIT
| Doc PR        | not needed

2 unrelated bugs! But, very minor :).

Commits
-------

d60425c Allow the logger to be null (as per every other bits in the FrameworkBundle)
3c4be3c Update the tests to also use `interface_exists`
2405eae Fixing bad class_exists vs interface_exists

Author: sroze

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php

@@ -970,7 +970,7 @@ private function addMessengerSection(ArrayNodeDefinition $rootNode)
             ->children()
                 ->arrayNode('messenger')
                     ->info('Messenger configuration')
-                    ->{!class_exists(FullStack::class) && class_exists(MessageBusInterface::class) ? 'canBeDisabled' : 'canBeEnabled'}()
+                    ->{!class_exists(FullStack::class) && interface_exists(MessageBusInterface::class) ? 'canBeDisabled' : 'canBeEnabled'}()
                     ->fixXmlConfig('adapter')
                     ->children()
                         ->arrayNode('routing')

src/Symfony/Bundle/FrameworkBundle/Resources/config/messenger.xml

@@ -52,7 +52,7 @@
 
         <!-- Logging & Debug -->
         <service id="messenger.middleware.debug.logging" class="Symfony\Component\Messenger\Debug\LoggingMiddleware">
-            <argument type="service" id="logger" />
+            <argument type="service" id="logger" on-invalid="null" />
 
             <tag name="messenger.bus_middleware" priority="10" />
             <tag name="monolog.logger" channel="messenger" />

src/Symfony/Bundle/FrameworkBundle/Tests/DependencyInjection/ConfigurationTest.php

@@ -251,7 +251,7 @@ class_exists(SemaphoreStore::class) && SemaphoreStore::isSupported() ? 'semaphor
                 ),
             ),
             'messenger' => array(
-                'enabled' => !class_exists(FullStack::class) && class_exists(MessageBusInterface::class),
+                'enabled' => !class_exists(FullStack::class) && interface_exists(MessageBusInterface::class),
                 'routing' => array(),
                 'middlewares' => array(
                     'validation' => array(

src/Symfony/Component/Messenger/Debug/LoggingMiddleware.php

@@ -21,7 +21,7 @@ class LoggingMiddleware implements MiddlewareInterface
 {
     private $logger;
 
-    public function __construct(LoggerInterface $logger)
+    public function __construct(LoggerInterface $logger = null)
     {
         $this->logger = $logger;
     }
@@ -31,6 +31,10 @@ public function __construct(LoggerInterface $logger)
      */
     public function handle($message, callable $next)
     {
+        if (null === $this->logger) {
+            return $next($message);
+        }
+
         $this->logger->debug('Starting handling message {class}', array(
             'message' => $message,
             'class' => get_class($message),