diff -u b/lib/Drupal/pgn/Serializer/Encoder/XmlEncoder.php b/lib/Drupal/pgn/Serializer/Encoder/XmlEncoder.php
--- b/lib/Drupal/pgn/Serializer/Encoder/XmlEncoder.php
+++ b/lib/Drupal/pgn/Serializer/Encoder/XmlEncoder.php
@@ -34,10 +34,10 @@
   protected $baseEncoder;
 
   /**
-   * Constucts the XmlEncoder object, creating a BaseXmlEncoder class also.
+   * Constucts the XmlEncoder object, creating a BaseXmlEncoder also if needed.
    */
-  public function __construct() {
-    $this->baseEncoder = new BaseXmlEncoder();
+  public function __construct(BaseXmlEncoder $base_xml_encoder = NULL) {
+    $this->baseEncoder = $base_xml_encoder ?: new BaseXmlEncoder();
   }
 
   /**