feat: create subscription tier range with named constructors

Author: adrianliz

exercises/tiered_pricing/solutions/adrianliz/java/src/main/java/tv/codely/checkout/InvalidSubscriptionTierRange.java

@@ -0,0 +1,8 @@
+package tv.codely.checkout;
+
+public final class InvalidSubscriptionTierRange extends RuntimeException {
+
+    public InvalidSubscriptionTierRange(final String message) {
+        super(message);
+    }
+}

exercises/tiered_pricing/solutions/adrianliz/java/src/main/java/tv/codely/checkout/SubscriptionTierRange.java

@@ -2,6 +2,7 @@
 
 import java.util.Objects;
 
+// [from, to]
 public final class SubscriptionTierRange {
 
     private final int numberOfSubscriptionsFrom;
@@ -12,14 +13,31 @@ public SubscriptionTierRange(int numberOfSubscriptionsFrom, int numberOfSubscrip
         this.numberOfSubscriptionsTo = numberOfSubscriptionsTo;
     }
 
-    public static SubscriptionTierRange first(int numberOfSubscriptionsTo) {
-        return new SubscriptionTierRange(1, numberOfSubscriptionsTo);
+    public static SubscriptionTierRange first(int numberOfSubscriptions) {
+        if (numberOfSubscriptions < 1) {
+            throw new InvalidSubscriptionTierRange(
+                "Number of subscriptions must be greater than 0");
+        }
+        return new SubscriptionTierRange(1, numberOfSubscriptions);
+    }
+
+    public static SubscriptionTierRange from(
+        final SubscriptionTierRange range,
+        final int numberOfSubscriptions) {
+
+        final int numberOfSubscriptionsFrom = range.numberOfSubscriptionsTo + 1;
+        final int numberOfSubscriptionsTo = numberOfSubscriptionsFrom + numberOfSubscriptions;
+        return new SubscriptionTierRange(numberOfSubscriptionsFrom, numberOfSubscriptionsTo);
     }
 
     public static SubscriptionTierRange last(int numberOfSubscriptionsFrom) {
         return new SubscriptionTierRange(numberOfSubscriptionsFrom, Integer.MAX_VALUE);
     }
 
+    public static SubscriptionTierRange last(final SubscriptionTierRange range) {
+        return new SubscriptionTierRange(range.numberOfSubscriptionsTo + 1, Integer.MAX_VALUE);
+    }
+
     public boolean isFirst() {
         return numberOfSubscriptionsFrom == 1;
     }

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

@@ -15,21 +15,26 @@
 public class TieredPricingShould {
 
     private static List<SubscriptionTier> defaultSubscriptionTiers() {
+        final var firstTierRange = SubscriptionTierRange.first(2);
+        final var secondTierRange = SubscriptionTierRange.from(firstTierRange, 7);
+        final var thirdTierRange = SubscriptionTierRange.from(secondTierRange, 14);
+        final var fourthTierRange = SubscriptionTierRange.from(thirdTierRange, 24);
+        final var lastTierRange = SubscriptionTierRange.last(fourthTierRange);
         return List.of(
             new SubscriptionTier(
-                SubscriptionTierRange.first(2),
+                firstTierRange,
                 new SubscriptionTierPrice(299)),
             new SubscriptionTier(
-                new SubscriptionTierRange(3, 10),
+                secondTierRange,
                 new SubscriptionTierPrice(239)),
             new SubscriptionTier(
-                new SubscriptionTierRange(11, 25),
+                thirdTierRange,
                 new SubscriptionTierPrice(219)),
             new SubscriptionTier(
-                new SubscriptionTierRange(26, 50),
+                fourthTierRange,
                 new SubscriptionTierPrice(199)),
             new SubscriptionTier(
-                SubscriptionTierRange.last(51),
+                lastTierRange,
                 new SubscriptionTierPrice(149)));
     }
 

exercises/tiered_pricing/solutions/adrianliz/java/src/test/java/tv/codely/checkout/mother/SubscriptionTierRangeMother.java

@@ -13,8 +13,8 @@ public static SubscriptionTierRange create(
         return new SubscriptionTierRange(numberOfSubscriptionsFrom, numberOfSubscriptionsTo);
     }
 
-    public static SubscriptionTierRange first(final int numberOfSubscriptionsTo) {
-        return SubscriptionTierRange.first(numberOfSubscriptionsTo);
+    public static SubscriptionTierRange first(final int numberOfSubscriptions) {
+        return SubscriptionTierRange.first(numberOfSubscriptions);
     }
 
     public static SubscriptionTierRange last(final int numberOfSubscriptionsFrom) {