Add fourth tier

Author: mikybars

exercises/tiered_pricing/solutions/mperezi/src/main/java/tv/codely/checkout/TieredPricing.java

@@ -7,7 +7,8 @@ public class TieredPricing {
   private enum Tier {
     FIRST(299.0, 1, 2),
     SECOND(239.0, 3, 10),
-    THIRD(219.0, 11, 25);
+    THIRD(219.0, 11, 25),
+    FOURTH(199.0, 26, 50);
 
     final double unitPrice;
     final int startRange;

exercises/tiered_pricing/solutions/mperezi/src/test/java/tv/codely/checkout/TieredPricingShould.java

@@ -42,6 +42,14 @@ void returnTotalPriceForThirdTier(int subscriptions) {
     assertThat(totalPrice).isEqualTo(subscriptions * 219.0);
   }
 
+  @ParameterizedTest
+  @MethodSource("rangeFourthTier")
+  void returnTotalPriceForFourthTier(int subscriptions) {
+    double totalPrice = tieredPricing.totalPrice(subscriptions);
+
+    assertThat(totalPrice).isEqualTo(subscriptions * 199.0);
+  }
+
   private static Stream<Integer> rangeFirstTier() {
     return IntStream.rangeClosed(1, 2).boxed();
   }
@@ -53,4 +61,8 @@ private static Stream<Integer> rangeSecondTier() {
   private static Stream<Integer> rangeThirdTier() {
     return IntStream.rangeClosed(11, 25).boxed();
   }
+
+  private static Stream<Integer> rangeFourthTier() {
+    return IntStream.rangeClosed(26, 50).boxed();
+  }
 }