allow null values for root nodes in YAML configs

Author: xabbuh

ContainerBuilder.php

@@ -271,12 +271,16 @@ public function addClassResource(\ReflectionClass $class)
      * @throws BadMethodCallException When this ContainerBuilder is frozen
      * @throws \LogicException        if the container is frozen
      */
-    public function loadFromExtension($extension, array $values = array())
+    public function loadFromExtension($extension, array $values = null)
     {
         if ($this->isFrozen()) {
             throw new BadMethodCallException('Cannot load from an extension on a frozen container.');
         }
 
+        if (func_num_args() < 2) {
+            $values = array();
+        }
+
         $namespace = $this->getExtension($extension)->getAlias();
 
         $this->extensionConfigs[$namespace][] = $values;

Loader/YamlFileLoader.php

@@ -425,7 +425,7 @@ private function loadFromExtensions(array $content)
                 continue;
             }
 
-            if (!is_array($values)) {
+            if (!is_array($values) && null !== $values) {
                 $values = array();
             }
 

Tests/Fixtures/includes/ProjectExtension.php

@@ -8,7 +8,14 @@ class ProjectExtension implements ExtensionInterface
 {
     public function load(array $configs, ContainerBuilder $configuration)
     {
-        $config = call_user_func_array('array_merge', $configs);
+        $configuration->setParameter('project.configs', $configs);
+        $configs = array_filter($configs);
+
+        if ($configs) {
+            $config = call_user_func_array('array_merge', $configs);
+        } else {
+            $config = array();
+        }
 
         $configuration->setDefinition('project.service.bar', new Definition('FooClass'));
         $configuration->setParameter('project.parameter.bar', isset($config['foo']) ? $config['foo'] : 'foobar');

Tests/Fixtures/yaml/null_config.yml

@@ -0,0 +1 @@
+project: ~

Tests/Loader/YamlFileLoaderTest.php

@@ -207,6 +207,17 @@ public function testExtensions()
         }
     }
 
+    public function testExtensionWithNullConfig()
+    {
+        $container = new ContainerBuilder();
+        $container->registerExtension(new \ProjectExtension());
+        $loader = new YamlFileLoader($container, new FileLocator(self::$fixturesPath.'/yaml'));
+        $loader->load('null_config.yml');
+        $container->compile();
+
+        $this->assertSame(array(null), $container->getParameter('project.configs'));
+    }
+
     public function testSupports()
     {
         $loader = new YamlFileLoader(new ContainerBuilder(), new FileLocator());