public static void CalculateCallCostTest(
     [Values("+79601258111")]string callingNumber,
     [Values("+79503468221")]string calledNumber,
     [Values("12.10.2012 11:13")]DateTime startTime,
     [Values("12.10.2012 11:15")]DateTime endTime)
 {
     Call call = new Call(calledNumber, calledNumber, startTime, endTime);
     Tariff tariff = Tariff.SelectTariffByID(6);
     StringAssert.Contains(BillingOperations.CalculateCallCost(call, tariff).ToString(), "48");
 }
 /// <summary>
 /// Рассчитывает стоимость звонка.
 /// </summary>
 /// <param name="call">Звонок</param>
 /// <param name="tariff">Тариф</param>
 /// <returns>Стоимость</returns>
 public static double CalculateCallCost(Call call, Tariff tariff)
 {
     Price price = tariff.SelectCallPrice(call.CalledNumber);
     double cost = price.Cost * (call.Duration.TotalSeconds);
     return Math.Round(cost, 2);
 }