@Test
  public void invoice_can_be_converted_to_ubl() throws IOException {
    byte[] xml = IOUtils.getResourceAsByteArray(RESOURCES_PATH + "/" + TEST_UBL_FILE_NAME);

    assertNotNull(xml);

    Invoice invoice = documentService.convertToInvoice(xml);

    assertNotNull(invoice);
    assertNotNull(invoice.getContent());

    byte[] convertedXml = documentService.convertToXml(invoice);

    assertNotNull(convertedXml);
  }