// should be private, but public because of unit test visibility
  public long getTotalFeeWeekends(Customer customer) throws Exception {

    // get price rate
    ParkingPriceRate parkingPriceRateWeekends = getParkingPriceRate(customer, false);

    return weekends.size() * parkingPriceRateWeekends.getFee();
  }
  // should be private, but public because of unit test visibility
  public long getTotalFeeWeekdays(Customer customer) throws Exception {

    // get price rate
    ParkingPriceRate parkingPriceRateWeekdays = getParkingPriceRate(customer, true);

    if (totalHours > 0) {
      return (totalHours - CONSESSION) * parkingPriceRateWeekdays.getFee();
    }

    return 0;
  }