public void TestDiscountAppliedAndSavedInRepository()
{
var orderId = Guid.NewGuid();
// HINT: Some dependency missing here?
var orderController = new OrderController(null);
var originalTotal = orderController.GetById(orderId).TotalPrice;
var modifiedTotal = orderController.ApplyDiscount(orderId, 10m).TotalPrice;
Assert.AreEqual(originalTotal*0.9m, modifiedTotal);
}