[Serializer] Add xml_format_output context option. Close #12517.

src/Symfony/Component/Serializer/Encoder/XmlEncoder.php

@@ -19,6 +19,7 @@ use Symfony\Component\Serializer\Exception\UnexpectedValueException;
  * @author Jordi Boggiano <j.boggiano@seld.be>
  * @author John Wards <jwards@whiteoctober.co.uk>
  * @author Fabian Vogler <fabian@equivalence.ch>
+ * @author Kévin Dunglas <dunglas@gmail.com>
  */
 class XmlEncoder extends SerializerAwareEncoder implements EncoderInterface, DecoderInterface, NormalizationAwareInterface
 {
@@ -514,6 +515,8 @@ class XmlEncoder extends SerializerAwareEncoder implements EncoderInterface, Dec
 
         // Set an attribute on the DOM document specifying, as part of the XML declaration,
         $xmlOptions = array(
+            // nicely formats output with indentation and extra space
+            'xml_format_output' => 'formatOutput',
             // the version number of the document
             'xml_version' => 'xmlVersion',
             // the encoding of the document

src/Symfony/Component/Serializer/Tests/Encoder/XmlEncoderTest.php

@@ -137,6 +137,26 @@ class XmlEncoderTest extends \PHPUnit_Framework_TestCase
         $this->assertSame($expected, $this->encoder->encode($array, 'xml', $context));
     }
 
+    public function testContext()
+    {
+        $array = array('person' => array('name' => 'George Abitbol'));
+        $expected = <<<XML
+<?xml version="1.0"?>
+<response>
+  <person>
+    <name>George Abitbol</name>
+  </person>
+</response>
+
+XML;
+
+        $context = array(
+            'xml_format_output' => true,
+        );
+
+        $this->assertSame($expected, $this->encoder->encode($array, 'xml', $context));
+    }
+
     public function testEncodeScalarRootAttributes()
     {
         $array = array(