feat: add object mothers in TieredPricingShould

Author: adrianliz

exercises/tiered_pricing/solutions/adrianliz/java/build.gradle

@@ -24,6 +24,7 @@ dependencies {
 
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.8.2'
     testImplementation 'org.springframework.boot:spring-boot-starter-test:2.6.4'
+    testImplementation 'com.github.javafaker:javafaker:1.0.2'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.8.2'
 }
 

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

@@ -36,4 +36,12 @@ public double getTotalPrice(int subscriptions) {
             .map(subscriptionTier -> subscriptionTier.getTotalPrice(subscriptions))
             .orElse(0D);
     }
+
+    public double getBasePrice(int subscriptions) {
+        return subscriptionTiers.stream()
+            .filter(subscriptionTier -> subscriptionTier.isInRange(subscriptions))
+            .findFirst()
+            .map(SubscriptionTier::unitPrice)
+            .orElse(0D);
+    }
 }

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

@@ -3,8 +3,9 @@
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertTrue;
 
-import java.util.List;
 import org.junit.jupiter.api.Test;
+import tv.codely.checkout.mother.IntegerMother;
+import tv.codely.checkout.mother.SubscriptionTierMother;
 
 public class TieredPricingShould {
 
@@ -15,27 +16,14 @@ void unit_test_example() {
 
     @Test
     void return_total_price_based_on_number_of_subscriptions() {
-        final var priceRanges =
-            List.of(
-                new SubscriptionTier(
-                    new SubscriptionTierRange(1, 2),
-                    new SubscriptionTierPrice(299)),
-                new SubscriptionTier(
-                    new SubscriptionTierRange(3, 10),
-                    new SubscriptionTierPrice(239)),
-                new SubscriptionTier(
-                    new SubscriptionTierRange(11, 25),
-                    new SubscriptionTierPrice(219)),
-                new SubscriptionTier(
-                    new SubscriptionTierRange(26, 50),
-                    new SubscriptionTierPrice(199)),
-                new SubscriptionTier(
-                    new SubscriptionTierRange(51, 100),
-                    new SubscriptionTierPrice(149)));
-        final var tieredPricing = new TieredPricing(priceRanges);
-        final var expectedPrice = priceRanges.get(1).unitPrice() * 3;
+        final var subscriptionTiers = SubscriptionTierMother.randoms();
+        final var tieredPricing = new TieredPricing(subscriptionTiers);
+        final var numberOfSubscriptions = IntegerMother.random();
+        final var expectedPrice =
+            tieredPricing.getBasePrice(numberOfSubscriptions) * numberOfSubscriptions;
+
+        final var totalPrice = tieredPricing.getTotalPrice(numberOfSubscriptions);
 
-        final var totalPrice = tieredPricing.getTotalPrice(3);
         assertEquals(expectedPrice, totalPrice);
     }
 

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

@@ -0,0 +1,8 @@
+package tv.codely.checkout.mother;
+
+public final class DoubleMother {
+
+    public static double randomBetween(final int min, final int max) {
+        return MotherCreator.random().number().randomDouble(2, min, max);
+    }
+}

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

@@ -0,0 +1,12 @@
+package tv.codely.checkout.mother;
+
+public final class IntegerMother {
+
+    public static int random() {
+        return MotherCreator.random().number().randomDigitNotZero();
+    }
+
+    public static int randomBetween(final int min, final int max) {
+        return MotherCreator.random().number().numberBetween(min, max);
+    }
+}

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

@@ -0,0 +1,12 @@
+package tv.codely.checkout.mother;
+
+import com.github.javafaker.Faker;
+
+public final class MotherCreator {
+
+    private static final Faker faker = new Faker();
+
+    public static Faker random() {
+        return faker;
+    }
+}

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

@@ -0,0 +1,33 @@
+package tv.codely.checkout.mother;
+
+import java.util.List;
+import java.util.concurrent.atomic.AtomicReference;
+import tv.codely.checkout.SubscriptionTier;
+import tv.codely.checkout.SubscriptionTierPrice;
+import tv.codely.checkout.SubscriptionTierRange;
+
+public final class SubscriptionTierMother {
+
+    public static SubscriptionTier create(
+        final SubscriptionTierRange range,
+        final SubscriptionTierPrice price) {
+
+        return new SubscriptionTier(range, price);
+    }
+
+    public static List<SubscriptionTier> randoms() {
+        final var subscriptionTierRanges = SubscriptionTierRangeMother.randoms();
+        final var previousSubscriptionTierPrice = new AtomicReference<>(299D);
+        
+        return subscriptionTierRanges.stream()
+            .map(range -> {
+                final var subscriptionTierPrice =
+                    DoubleMother.randomBetween(
+                        previousSubscriptionTierPrice.get().intValue() - 60,
+                        previousSubscriptionTierPrice.get().intValue() - 20);
+                previousSubscriptionTierPrice.set(subscriptionTierPrice);
+                return create(range, new SubscriptionTierPrice(subscriptionTierPrice));
+            })
+            .toList();
+    }
+}

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

@@ -0,0 +1,14 @@
+package tv.codely.checkout.mother;
+
+import tv.codely.checkout.SubscriptionTierPrice;
+
+public final class SubscriptionTierPriceMother {
+
+    public static SubscriptionTierPrice create(final double value) {
+        return new SubscriptionTierPrice(value);
+    }
+
+    public static SubscriptionTierPrice randomBetween(final int min, final int max) {
+        return create(DoubleMother.randomBetween(min, max));
+    }
+}

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

@@ -0,0 +1,39 @@
+package tv.codely.checkout.mother;
+
+import java.util.ArrayList;
+import java.util.List;
+import tv.codely.checkout.SubscriptionTierRange;
+
+public final class SubscriptionTierRangeMother {
+
+    public static SubscriptionTierRange create(
+        final int numberOfSubscriptionsFrom,
+        final int numberOfSubscriptionsTo) {
+
+        return new SubscriptionTierRange(numberOfSubscriptionsFrom, numberOfSubscriptionsTo);
+    }
+
+    public static List<SubscriptionTierRange> randoms() {
+        final var subscriptionTiers = new ArrayList<SubscriptionTierRange>();
+        final var numberOfTiers = IntegerMother.randomBetween(1, 6);
+        final var minSubscriptionsInTier = 3;
+        final var maxSubscriptionsInTier =
+            IntegerMother.randomBetween(minSubscriptionsInTier + 1, 20);
+
+        var lastNumberOfSubscriptionsTo = 0;
+
+        for (int i = 0; i < numberOfTiers; i++) {
+            final var numberOfSubscriptionsFrom = lastNumberOfSubscriptionsTo + 1;
+            final var numberOfSubscriptionsTo =
+                IntegerMother.randomBetween(
+                    numberOfSubscriptionsFrom + 1,
+                    maxSubscriptionsInTier * (i + 1));
+
+            lastNumberOfSubscriptionsTo = numberOfSubscriptionsTo;
+
+            subscriptionTiers.add(create(numberOfSubscriptionsFrom, numberOfSubscriptionsTo));
+        }
+
+        return subscriptionTiers;
+    }
+}