Better ServiceLocatorAwareInterface duck typing

Do not check if ServiceLocatorAwareInterface exists, as that will skip
the initializer when it does, but the instance does not implement it and
*does* fit duck typing rules.

src/Controller/ControllerManager.php

@@ -54,8 +54,11 @@ public function __construct($configOrContainerInstance, array $v3config = [])
         $this->addInitializer([$this, 'injectEventManager']);
         $this->addInitializer([$this, 'injectConsole']);
         $this->addInitializer([$this, 'injectPluginManager']);
-        $this->addInitializer([$this, 'injectServiceLocator']);
         parent::__construct($configOrContainerInstance, $v3config);
+
+        // Added after parent construction, as v2 abstract plugin managers add
+        // one during construction.
+        $this->addInitializer([$this, 'injectServiceLocator']);
     }
 
     /**
@@ -204,6 +207,7 @@ public function injectPluginManager($first, $second)
      */
     public function injectServiceLocator($first, $second)
     {
+        printf("In %s\n", __METHOD__);
         if ($first instanceof ContainerInterface) {
             $container = $first;
             $controller = $second;
@@ -217,7 +221,7 @@ public function injectServiceLocator($first, $second)
             $container = $container->getServiceLocator() ?: $container;
         }
 
-        if (! interface_exists(ServiceLocatorAwareInterface::class)
+        if (! $controller instanceof ServiceLocatorAwareInterface
             && method_exists($controller, 'setServiceLocator')
         ) {
             trigger_error(sprintf(

src/Service/ServiceManagerConfig.php

@@ -142,7 +142,7 @@ public function __construct(array $config = [])
                     $instance->setServiceLocator($container);
                 }
 
-                if (! interface_exists(ServiceLocatorAwareInterface::class)
+                if (! $instance instanceof ServiceLocatorAwareInterface
                     && method_exists($instance, 'setServiceLocator')
                 ) {
                     trigger_error(sprintf(

test/Service/ServiceManagerConfigTest.php

@@ -219,10 +219,10 @@ public function testEventManagerInitializerCanBeReplaced()
 
     public function testServiceLocatorAwareInitializerInjectsDuckTypedImplementations()
     {
-        $serviceManager = new ServiceManager(['factories' => [
+        $serviceManager = new ServiceManager();
+        (new ServiceManagerConfig(['factories' => [
             TestAsset\DuckTypedServiceLocatorAware::class => InvokableFactory::class,
-        ]]);
-        (new ServiceManagerConfig())->configureServiceManager($serviceManager);
+        ]]))->configureServiceManager($serviceManager);
 
         $instance = $serviceManager->get(TestAsset\DuckTypedServiceLocatorAware::class);
         $this->assertInstanceOf(TestAsset\DuckTypedServiceLocatorAware::class, $instance);