feat(tiered_pricing): 🔴 test for non positive values

Author: oflorez1381

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

@@ -5,6 +5,7 @@
 import java.util.stream.IntStream;
 
 import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 public class TieredPricingShould {
 
@@ -48,6 +49,13 @@ void calculate_total_value_for_fifth_pricing_tier() {
         assertEquals(calculateTotalPriceExpected(tier.getUnitPrice(), subscription), pricing.calculateTotalPrice(subscription));
     }
 
+    @Test
+    void throws_illegal_argument_when_subscription_be_non_positive_value() {
+        var pricing = new TieredPricing();
+        var subscription = IntStream.rangeClosed(-100000, 0).findAny().getAsInt();
+        assertThrows(IllegalArgumentException.class, () ->  pricing.calculateTotalPrice(subscription));
+    }
+
     private int retrieveSubscriptionGivenTier(Tier tier) {
         return IntStream.rangeClosed(tier.getLowerLimit(), tier.getUpperLimit()).findAny().getAsInt();
     }