Quantity Discount

We want to offer a discount based on the number of options added to the coffee order.

But first, let's leverage the Enum to make it easier to calculate the price of the SizeOption.

• Modify your Size class to use SizeOption for the price by creating a method called cost() that returns the private variable cost, where the values are defined in the call to the constructor. For an Enum example, see this class:

public enum Priority {  
  HIGH(3),
  MEDIUM(2),
  LOW(1);

  private final int code;

  Priority(int code) {
    this.code = code;
  }

  public int code() {
    return code;
  }
}

Once you've updated your Size.price() method to use the SizeOption's cost() method, ensure all tests continue to pass.

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The Discounts

Creamer and Sweetener will have quantity discounts, but the quantity that triggers the discount is different for Creamer vs. Sweetener.

Creamer Discount

If 2 (two) or more Creamers are added, then we want a discount of 15 cents. For example, 2 Milk options normally costs 50 cents, but with the discount, should cost 35 cents (50 - 15). Adding only 1 Milk (or Half-n-Half) would not be discounted.

Sweetener Discount:

If 3 (three) or more Sweeteners are added, then the discount is 5 cents. For example, 3 Sugars normally costs 30 cents, but with the discount, it should cost 25 cents (30 - 5). Adding only one or two sweeteners would not be discounted.

Failing Creamer Test

Here's a failing Creamer test that you can start with.

  @Test
  public void twoMilksShouldBeDiscountedTo35Cents() throws Exception {
    Creamer creamer = new Creamer("milk", 2);

    assertThat(creamer.price())
        .isEqualTo(35);
  }

Make it pass, then make sure all other tests pass.

Failing Sweetener Test

Remember, for Sweetener, you need quantity of 3 to get the discount.

  @Test
  public void threeSugarsShouldBeDiscountedTo25Cents() throws Exception {
    Sweetener sugar = new Sweetener("sugar", 3);

    assertThat(sugar.price())
        .isEqualTo(25);
  }

The above test should fail, so make it pass, but also make sure all other existing tests pass!

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Once you've completed the above steps, check in with the instructor to review your code.

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