public void CallHistoryTest()
        {
            GSM myPhone = new GSM("Lumia", "Nokia");
            //public Call(string date, string time, string dialed, long duration)
            List <Call> someCalls = new List <Call> {
                new Call("02.02.2015", "15:45", "0896232333", 56),
                new Call("03.18.2015", "11:45", "0852454555", 13),
                new Call("01.02.2015", "00:05", "0899656598", 118),
                new Call("03.15.2015", "18:32", "0896232333", 65)
            };

            foreach (Call a in someCalls)
            {
                myPhone.AddCall(a);
            }
            myPhone.DisplayCalls();
            double price = 0.37;

            Console.WriteLine("With price of 0.37 per minute, the total cost of the calls:" + myPhone.CalcPrice(price / 60));
            Console.WriteLine("Removing the longest call ...");
            myPhone.DeleteCall(someCalls[2]);
            Console.WriteLine("With price of 0.37 per minute, the total cost of the calls:" + myPhone.CalcPrice(price / 60));
            myPhone.ClearHistory();
            Console.WriteLine("History Cleared");
            Console.WriteLine("Current History:");
            myPhone.DisplayCalls();
        }
 public void CallHistoryTest()
 {
     GSM myPhone = new GSM("Lumia", "Nokia");
             //public Call(string date, string time, string dialed, long duration)
     List<Call> someCalls =new List<Call> {
     new Call("02.02.2015", "15:45", "0896232333", 56),
     new Call("03.18.2015", "11:45", "0852454555", 13),
     new Call("01.02.2015", "00:05", "0899656598", 118),
     new Call("03.15.2015", "18:32", "0896232333", 65)};
     foreach (Call a in someCalls)
     { myPhone.AddCall(a); }
     myPhone.DisplayCalls();
     double price = 0.37;
     Console.WriteLine("With price of 0.37 per minute, the total cost of the calls:" + myPhone.CalcPrice(price/60));
     Console.WriteLine("Removing the longest call ...");
     myPhone.DeleteCall(someCalls[2]);
     Console.WriteLine("With price of 0.37 per minute, the total cost of the calls:" + myPhone.CalcPrice(price / 60));
     myPhone.ClearHistory();
     Console.WriteLine("History Cleared");
     Console.WriteLine("Current History:");
     myPhone.DisplayCalls();
 }