public void TestSpeedyDelivery()
 {
     ShippingCostCalculator calculator = new ShippingCostCalculator(new SpeedyShippingCalculator());
     double price = calculator.Calculate(Order);
     Assert.AreEqual(price, 60);
 }
 public void TestRegularDelivery()
 {
     ShippingCostCalculator calculator = new ShippingCostCalculator(new RegularShippingCalculator());
     double price = calculator.Calculate(Order);
     Assert.AreEqual(price, 35);
 }