Implemented check on interface implementation

src/Symfony/Component/Security/Core/Authentication/AuthenticationProviderManager.php

@@ -48,6 +48,12 @@ class AuthenticationProviderManager implements AuthenticationManagerInterface
             throw new \InvalidArgumentException('You must at least add one authentication provider.');
         }
 
+        foreach ($providers as $provider) {
+            if (!$provider instanceof AuthenticationProviderInterface) {
+                throw new \InvalidArgumentException(sprintf('Provider "%s" must implement the AuthenticationProviderInterface.', get_class($provider)));
+            }
+        }
+
         $this->providers = $providers;
         $this->eraseCredentials = (bool) $eraseCredentials;
     }

src/Symfony/Component/Security/Core/Tests/Authentication/AuthenticationProviderManagerTest.php

@@ -27,6 +27,16 @@ class AuthenticationProviderManagerTest extends \PHPUnit_Framework_TestCase
         new AuthenticationProviderManager(array());
     }
 
+    /**
+     * @expectedException \InvalidArgumentException
+     */
+    public function testAuthenticateWithProvidersWithIncorrectInterface()
+    {
+        new AuthenticationProviderManager(array(
+            new \stdClass(),
+        ));
+    }
+
     public function testAuthenticateWhenNoProviderSupportsToken()
     {
         $manager = new AuthenticationProviderManager(array(