Shopping Cart – Part 2

Test-Driven Development: write tests before writing code.

Unit testing results in modular code. Modular code is:

• easy to test.
• immune to bugs.
• easy to understand.
• scalable.

Task 1: @Before

@Before runs a method before each test.

• Annotate a void method named setup with @Before.
• Inside setup, set cart equal to a new object of the Cart class.

Task 2

1. Create a test that fails

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Inside @Before, add two Item objects:

     cart.add(new Item("Pepsi", 1.99));
     cart.add(new Item("Crush", 1.99));

Inside Cart.java, create the add method.

    /**
     * Function name: add
     * @param item 
     * 
     * Inside the function:
     *   1. adds an Item object
     */

Inside CartTest.java, write a unit test named itemAddedTest. itemAddedTest asserts that a cart contains() an item after it's added.

Inside Cart.java, write code to make the test fail.

 /**
  * Function name: contains
  * @param item
  * @return (boolean)
  * 
  * Inside the function:
  *    1. checks if items list contains() item.
  */

2. Make the test pass

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Hint: contains() needs your equals method to compare each item against the parameter. See lesson: The equals() method.

    public boolean equals(Object obj) {
    
        return false if parameter is null.
        
        return false if parameter isn't instance of Item class.

        typecast the object to Item.
        
        compare fields from both objects and return the result.
    }

3. Refactor

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Can the code be simpler? No.

Task 3

1. Create a test that fails

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Write a unit test named skipsDuplicate. skipsDuplicate asserts that add() returns false for a duplicate item.

Inside Cart.java, write code to make the test fail.

    /**
     * Function name: add
     * @param item 
     * @return (boolean) <-------
     * 
     * Inside the function:
     *   1. adds an Item object
     *   2. returns true <-------
     */

2. Make the test pass

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    /**
     * Function name: add
     * @param item 
     * @return (boolean)
     * 
     * Inside the function:
     *   1. returns false if item exists. <-------
     *   1. adds an Item object
     *   2. returns true if item gets added;  <-------
     */

3. Refactor

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Can the code be simpler? No.

Good Luck!

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