discount percentages (step4)

Author: Félix Carpena

src/main/java/group/rohlik/entity/Cart.java

@@ -74,18 +74,19 @@ private double totalLinesPrice() {
                 .sum();
     }
 
-    private double totalDiscountsPrice() {
+    private double totalDiscountsPercentage() {
         return discounts
                 .stream()
                 .mapToDouble(Discount::getValue)
                 .sum();
     }
 
     public double totalPrice() {
+        double totalLinesPrice = totalLinesPrice();
         return Math.max(
                 0,
                 BigDecimal
-                        .valueOf(totalLinesPrice() - totalDiscountsPrice())
+                        .valueOf(totalLinesPrice - (totalLinesPrice * totalDiscountsPercentage() / 100))
                         .setScale(2, RoundingMode.CEILING)
                         .doubleValue()
         );

src/test/java/group/rohlik/acceptance/steps/DiscountSteps.java

@@ -10,7 +10,7 @@
 public class DiscountSteps {
     private final DiscountRepository discountRepository;
 
-    @Given("there is a cart discount {string} for {double} euros with code {string}")
+    @Given("there is a cart discount {string} for {double} % with code {string}")
     @Transactional
     public void thereIsACartDiscountWithCode(String name, double value, String code) {
         Discount discount = Discount.create(name, code, value);

src/test/resources/features/add_discount_to_cart.feature

@@ -8,8 +8,8 @@ Feature: Add discount to cart
       | sku | name     | price |
       | 001 | potatoes | 2.5   |
       | 002 | water    | 0.95  |
-    And there is a cart discount "free shipping" for 1 euros with code "FREE-SHIPPING"
-    And there is a cart discount "special offer" for 10 euros with code "SPECIAL-OFFER"
+    And there is a cart discount "free shipping" for 10 % with code "FREE-SHIPPING"
+    And there is a cart discount "special offer" for 95 % with code "SPECIAL-OFFER"
     And I have a cart
 
   Scenario: No discounts
@@ -20,14 +20,14 @@ Feature: Add discount to cart
   Scenario: Add discount
     Given I add 2 units of product "001" to my cart
     When I apply "FREE-SHIPPING" discount to my cart
-    Then the cart's total cost should be 4.0 euros
+    Then the cart's total cost should be 4.50 euros
     And there should be discount "free shipping" in my cart
 
   Scenario: Add discount only apply once
     Given I add 2 units of product "001" to my cart
     And I apply "FREE-SHIPPING" discount to my cart
     When I apply "FREE-SHIPPING" discount to my cart
-    Then the cart's total cost should be 4.0 euros
+    Then the cart's total cost should be 4.50 euros
     And there should be discount "free shipping" in my cart
 
   Scenario: Cart total should be always positive
@@ -37,3 +37,19 @@ Feature: Add discount to cart
     Then the cart's total cost should be 0.0 euros
     And there should be discount "free shipping" in my cart
     And there should be discount "special offer" in my cart
+
+  Scenario Outline: Add discount examples
+    Given the following products exist:
+      | sku | name         | price           |
+      | 003 | orange juice | <product_price> |
+    And there is a cart discount "super discount" for <percentage> % with code "SUPER-DISCOUNT"
+    Given I add <product_quantity> units of product "003" to my cart
+    When I apply "SUPER-DISCOUNT" discount to my cart
+    Then the cart's total cost should be <cart_total> euros
+    And there should be discount "super discount" in my cart
+    Examples:
+      | product_price | product_quantity | percentage | cart_total |
+      | 21.0          | 1                | 10         | 18.90      |
+      | 20.0          | 2                | 15         | 34.0       |
+      | 5.0           | 3                | 3          | 14.55      |
+      | 5.0           | 3                | 0          | 15.00      |