Elastica\Query\MoreLikeThis::setFields PHP Method

    public function setFields(array $fields)
    {
        return $this->setParam('fields', $fields);
    }

 /**
  * @group unit
  */
 public function testSetFields()
 {
     $query = new MoreLikeThis();
     $fields = array('firstname', 'lastname');
     $query->setFields($fields);
     $data = $query->toArray();
     $this->assertEquals($fields, $data['more_like_this']['fields']);
 }