Implementing More Features for the Shopping Cart

Welcome to the fourth unit of this course dedicated to practicing Test Driven Development (TDD). In this lesson, we will continue building our ShoppingCart system by adding more features using Rust and its built-in testing framework.

This course places emphasis on hands-on practice, where you will receive requirements through tests one at a time. Your task is to write tests and implement the code that makes each test pass, simulating a real-world TDD environment.

Remember to use the core concepts of the Red-Green-Refactor cycle while completing these coding exercises. I'm here to help if needed!

• Description: Attempting to remove a product that is not present in the cart should return a result indicating that the product was not found.
• Details:
  • Implement the removal via a fn remove_item(&mut self, id: &str) -> Result<(), String> function.
  • Ensure the function returns an Err with the message "Item not found" if the product is not in the cart.
• Examples: Attempting to remove a product with id: "999" should return an error with the message "Item not found".

• Description: Applying a percentage discount should adjust the total price of the products in the cart accordingly.
• Details:
  • Implement a fn apply_discount(&mut self, percentage: f64) method to apply a percentage discount to the total.
  • Ensure get_total() returns the adjusted price after applying the discount.
• Examples: Applying a 10% discount to a total price of 100.0 should result in a new total of 90.0.

• Description: Automatically apply a 10% discount when the total price of products in the cart exceeds $150.
• Details:
  • If the total exceeds 150, the 10% discount should be automatically applied.
  • The get_total() method should return the discounted total when the discount is applicable.
• Examples: Adding a "Book" with a price of 200.0 should result in a total of 180.0 after applying the bulk discount.