Cielo\Transaction::setReturnURL PHP Method

    public function setReturnURL($returnURL)
    {
        if ($returnURL !== null && !filter_var($returnURL, FILTER_VALIDATE_URL)) {
            throw new \UnexpectedValueException('URL de retorno inválida');
        }
        $this->returnURL = $returnURL;
    }

 /**
  * @test
  */
 public function setReturnURLThrowsUnexpectedValue()
 {
     $this->setExpectedException(\UnexpectedValueException::class);
     $this->transaction->setReturnURL(null);
 }