add test and documentation for using a service id string instead of a closure

doc/providers/security.rst

@@ -495,8 +495,8 @@ Defining a custom User Provider
 Using an array of users is simple and useful when securing an admin section of
 a personal website, but you can override this default mechanism with you own.
 
-The ``users`` setting can be defined as a service that returns an instance of
-`UserProviderInterface
+The ``users`` setting can be defined as a service or an service id that returns
+an instance of `UserProviderInterface
 <http://api.symfony.com/master/Symfony/Component/Security/Core/User/UserProviderInterface.html>`_::
 
     'users' => function () use ($app) {

tests/Silex/Tests/Provider/SecurityServiceProviderTest.php

@@ -278,6 +278,35 @@ class SecurityServiceProviderTest extends WebTestCase
         $this->assertEquals('fabien', $app['user']->getUsername());
     }
 
+    public function testUserAsServiceString()
+    {
+        $users = array(
+            'fabien' => array('ROLE_ADMIN', '5FZ2Z8QIkA7UTZ4BYkoC+GsReLf569mSKDsfods6LYQ8t+a8EW9oaircfMpmaLbPBh4FOBiiFyLfuZmTSUwzZg=='),
+        );
+
+        $app = new Application();
+        $app->register(new SecurityServiceProvider(), array(
+            'security.firewalls' => array(
+                'default' => array(
+                    'http' => true,
+                    'users' => 'my_user_provider',
+                ),
+            ),
+        ));
+        $app['my_user_provider'] = $app['security.user_provider.inmemory._proto']($users);
+        $app->get('/', function () { return 'foo'; });
+
+        $request = Request::create('/');
+        $app->handle($request);
+        $this->assertNull($app['user']);
+
+        $request->headers->set('PHP_AUTH_USER', 'fabien');
+        $request->headers->set('PHP_AUTH_PW', 'foo');
+        $app->handle($request);
+        $this->assertInstanceOf('Symfony\Component\Security\Core\User\UserInterface', $app['user']);
+        $this->assertEquals('fabien', $app['user']->getUsername());
+    }
+
     public function testUserWithNoToken()
     {
         $app = new Application();