public void Booking_should_calculate_total_cost() { DateTime pickupDate = new DateTime(2012, 12, 31); var car = new CarBObj(new SupplierBObj()); car.setDailyRate(30); var booking = BookingBObj.newBooking(car); booking.setBookingRange(pickupDate, 10); Assert.AreEqual(car.dailyRate() * 10, booking.getTotalCost()); Assert.AreEqual(300, booking.getTotalCost()); }