Practice good Test Driven Development (TDD) by writing tests for each component of the program, before writing the code.
(1) Write a test that describes a feature of the software. Run the test, and watch it fail. Watching it fail is crucial! (2) Write code that makes all the tests pass. (3) Look for opportunities to clarify your code.
- Write a test
- Watch it fail
- Make it pass
- Clarify
- Repeat
Refer to the lesson Automated Tests.
We are going to build a RestaurantBill
class that will
- Keep track of items we order
- Give us a bill with the items' total cost, plus tax
- Let us add a tip
- See the final bill (With item's total cost, tax and tip)
This class will not be using any user input.
Start working in restaurant_bill_spec.rb by setting up a describes
block.
Write a test, run rake, then uncomment only the code that is needed to pass that test in restaurant_bill.rb. Get that test to pass before moving on to the next one. Your first tests should follow the order of the list below.
- Test that a new instance of RestaurantBill is created with
RestaurantBill.new
- Test that RestaurantBill is initialized with the attribute
ordered_items
, an empty array. - Test the method
order_item
, it should expect thatordered_items
includes the new item. - Test that if the
order_item
method is called 3 times, there are 3 elements in theordered_items
array.
Now add your own tests and code for the following features
- A method that returns a total of all the item's costs combined, with tax
- A method to add a tip. Returns total with tip.
- A way to see the final cost of a bill, with tax and tip
- The class should have the following attributes: ordered_items, tip and total
If you're feeling stuck, refer to 'What should I test'.