add unit test method

Author: mikaelcom

tests/DomDocumentHandlerTest.php

@@ -104,6 +104,15 @@ public function testGetElementsByName()
         $this->assertContainsOnlyInstancesOf('\WsdlToPhp\DomHandler\ElementHandler', $instance->getElementsByName('element'));
         $this->assertEmpty($instance->getElementsByName('foo'));
     }
+    /**
+     *
+     */
+    public function testGetElementByNameIsNull()
+    {
+        $instance = self::bingInstance();
+
+        $this->assertNull($instance->getElementByName('foo'));
+    }
     /**
      *
      */