[Config][FrameworkBundle] Allow to dump extension config reference sub path

Author: ogizanagi

Definition/Dumper/YamlReferenceDumper.php

@@ -33,6 +33,32 @@ public function dump(ConfigurationInterface $configuration)
         return $this->dumpNode($configuration->getConfigTreeBuilder()->buildTree());
     }
 
+    public function dumpAtPath(ConfigurationInterface $configuration, $path)
+    {
+        $rootNode = $node = $configuration->getConfigTreeBuilder()->buildTree();
+
+        foreach (explode('.', $path) as $step) {
+            if (!$node instanceof ArrayNode) {
+                throw new \UnexpectedValueException(sprintf('Unable to find node at path "%s.%s"', $rootNode->getName(), $path));
+            }
+
+            /** @var NodeInterface[] $children */
+            $children = $node instanceof PrototypedArrayNode ? $this->getPrototypeChildren($node) : $node->getChildren();
+
+            foreach ($children as $child) {
+                if ($child->getName() === $step) {
+                    $node = $child;
+
+                    continue 2;
+                }
+            }
+
+            throw new \UnexpectedValueException(sprintf('Unable to find node at path "%s.%s"', $rootNode->getName(), $path));
+        }
+
+        return $this->dumpNode($node);
+    }
+
     public function dumpNode(NodeInterface $node)
     {
         $this->reference = '';

Tests/Definition/Dumper/YamlReferenceDumperTest.php

@@ -25,6 +25,61 @@ public function testDumper()
         $this->assertEquals($this->getConfigurationAsString(), $dumper->dump($configuration));
     }
 
+    public function provideDumpAtPath()
+    {
+        return array(
+            'Regular node' => array('scalar_true', <<<EOL
+scalar_true:          true
+EOL
+            ),
+            'Array node' => array('array', <<<EOL
+# some info
+array:
+    child1:               ~
+    child2:               ~
+
+    # this is a long
+    # multi-line info text
+    # which should be indented
+    child3:               ~ # Example: example setting
+EOL
+            ),
+            'Regular nested' => array('array.child2', <<<EOL
+child2:               ~
+EOL
+            ),
+            'Prototype' => array('cms_pages.page', <<<EOL
+# Prototype
+page:
+
+    # Prototype
+    locale:
+        title:                ~ # Required
+        path:                 ~ # Required
+EOL
+            ),
+            'Nested prototype' => array('cms_pages.page.locale', <<<EOL
+# Prototype
+locale:
+    title:                ~ # Required
+    path:                 ~ # Required
+EOL
+            ),
+        );
+    }
+
+    /**
+     * @dataProvider provideDumpAtPath
+     */
+    public function testDumpAtPath($path, $expected)
+    {
+        $configuration = new ExampleConfiguration();
+
+        $dumper = new YamlReferenceDumper();
+
+        $this->assertSame(trim($expected), trim($dumper->dumpAtPath($configuration, $path)));
+    }
+
     private function getConfigurationAsString()
     {
         return <<<'EOL'