Welcome to the fifth and final unit of this course, focused on practicing the principles of Test Driven Development (TDD) using C++ and Google Test. We're going to continue building our ShoppingCart system by integrating even more sophisticated features into our class.

In this course, emphasis is placed on hands-on practice, where you'll receive requirements through tests, one at a time. Your task is to write tests AND implement code that makes each test pass, simulating a real-world TDD environment. In previous lessons, tests were provided to guide you, but now it's your turn to define them!

Remember to apply the core concepts of the Red-Green-Refactor cycle while completing these coding exercises. Ask questions if you need any clarification!

• Description: The cart should enforce a maximum quantity limit of 10 for a single type of item, preventing more than this allowed amount from being added.
• Details
  • Utilize the AddItem(item, quantity) method to add items to the cart.
  • Ensure an exception is raised when adding a quantity that exceeds the limit of 10 for a single item.
  • The exception should be of type std::invalid_argument with the message "Maximum quantity exceeded."
• Examples: Attempting to add 11 units of an item should throw a std::invalid_argument exception indicating "Maximum quantity exceeded."

• Description: When an item is added to the cart, it should be possible to retrieve that item's details using its ID, including the product information and the quantity in the cart.
• Details
  • Enable items to be added using the AddItem() method with specific IDs.
  • Ensure that GetItem(id) returns the correct item details, including the quantity, after being added to the cart.
• Examples: Adding a "Book" with ID 1 and price 10 and retrieving by ID 1 should return an object with Id: 1, Name: 'Book', Price: 10, Quantity: 1.

• Description: Applying a valid discount code should reduce the total price of items in the cart by the specified discount percentage.
• Details
  • Use the ApplyDiscountCode(code) method to apply a discount.
  • Support valid discount codes stored in a std::map, such as HOLIDAY25 for a 25% discount.
  • Update GetTotal() to reflect the discounted price.
• Examples: Applying the discount code 'HOLIDAY25' to a product "Book" with a price of 100 should reduce the total to 75.