Welcome to your fifth and final unit for this course, focused on practicing the principles of Test Driven Development (TDD) using Scala and ScalaTest. We’ll continue building our ShoppingCart system by integrating more sophisticated features into the class.

In this course, the 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 clarification!

These requirements introduce more sophisticated capabilities for the ShoppingCart class, focusing on robust item management, discount application, and quantity handling. These features will challenge you to apply TDD principles effectively and enhance the system's functionality.

Let's take a look at the final set of requirements.

• 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(product: Product, quantity: Int) 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’s message should clearly state "Maximum quantity exceeded" when the limit is breached.

• Examples: Attempting to add 11 units of an item should throw a custom InvalidCartOperationException 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: String): CartItem returns the correct item details, including the quantity, after being added to the cart.

• Examples: Adding a "Book" of ID "1" with a price of 10 and retrieving by ID "1" should return { Id: "1", Name: "Book", Price: 10, Quantity: 1 }.