public static void StartTest() { var display = new Display(3, 300); var battery = new Battery("S.NO.W3TT543"); GSM addPhone = new GSM("Hero", "HTC", 100m, "4ovek", battery, display); DateTime time = new DateTime(2013, 1, 10, 11, 00, 00); string number = "08837656282"; int duration = 60; addPhone.AddCall(time, number, duration); DateTime time1 = new DateTime(2013, 1, 10, 12, 00, 00); string number1 = "08957656282"; int duration1 = 135; addPhone.AddCall(time1, number1, duration1); DateTime time2 = new DateTime(2013, 1, 10, 12, 05, 00); string number2 = "08957656282"; int duration2 = 35; addPhone.AddCall(time2, number2, duration2); var callHistory = addPhone.CallHistory; Console.WriteLine(); foreach (var call in callHistory) { Console.WriteLine("Call: {0}\t{1}\t{2} secconds", call.Phone, call.Time, call.Duration); } Console.WriteLine("The bill is: {0}$", addPhone.Bill(0.37m)); callHistory = callHistory.OrderByDescending(x => x.Duration).ToList(); addPhone.DelCall(callHistory[0]); Console.WriteLine("After deleting the longest call the bill is: {0}$", addPhone.Bill(0.37m)); addPhone.ClearCallHistory(); Console.WriteLine("Printing call history (should be empty)"); callHistory = addPhone.CallHistory; foreach (var call in callHistory) { Console.WriteLine("Call: {0}\t{1}\t{2} secconds", call.Phone, call.Time, call.Duration); } }