Elastica\Query::setScriptFields PHP Method

    public function setScriptFields($scriptFields)
    {
        if (is_array($scriptFields)) {
            $scriptFields = new ScriptFields($scriptFields);
        }
        return $this->setParam('script_fields', $scriptFields);
    }

 public function testQuery()
 {
     $type = $this->index->getType('test');
     $doc = new Document(1, array('firstname' => 'guschti', 'lastname' => 'ruflin'));
     $type->addDocument($doc);
     $this->index->refresh();
     $query = new Query();
     $script = new Script('1 + 2');
     $scriptFields = new ScriptFields(array('test' => $script));
     $query->setScriptFields($scriptFields);
     $resultSet = $type->search($query);
     $first = $resultSet->current()->getData();
     // 1 + 2
     $this->assertEquals(3, $first['test']);
 }