refactor: add specialized classes for handling each case

Java/src/main/java/com/gildedrose/GRItem.java

@@ -1,97 +0,0 @@
-package com.gildedrose;
-
-public class GRItem {
-
-    private static final String AGED_BRIE = "Aged Brie";
-    private static final String SULFURAS = "Sulfuras, Hand of Ragnaros";
-    private static final int MAX_QUALITY = 50;
-    private static final int MIN_QUALITY = 0;
-
-    private final Item item;
-
-    public GRItem(Item item) {
-        this.item = item;
-    }
-
-    public GRItem(String name, int sellIn, int quality) {
-        this.item = new Item(name, sellIn, quality);
-    }
-
-    public String getName() {
-        return item.name;
-    }
-
-    public int getSellIn() {
-        return item.sellIn;
-    }
-
-    public int getQuality() {
-        return item.quality;
-    }
-
-    public void updateQuality() {
-        if (!item.name.equals(AGED_BRIE)
-                && !item.name.equals("Backstage passes to a TAFKAL80ETC concert")) {
-            if (item.quality > 0) {
-                if (!item.name.equals(SULFURAS)) {
-                    item.quality = item.quality - 1;
-                }
-            }
-        } else {
-            if (item.quality < MAX_QUALITY) {
-                item.quality = item.quality + 1;
-
-                if (item.name.equals("Backstage passes to a TAFKAL80ETC concert")) {
-                    if (item.sellIn < 11) {
-                        if (item.quality < MAX_QUALITY) {
-                            item.quality = item.quality + 1;
-                        }
-                    }
-
-                    if (item.sellIn < 6) {
-                        if (item.quality < MAX_QUALITY) {
-                            item.quality = item.quality + 1;
-                        }
-                    }
-                }
-            }
-        }
-
-        if (!item.name.equals(SULFURAS)) {
-            item.sellIn = item.sellIn - 1;
-        }
-
-        if (item.sellIn < 0) {
-            if (!item.name.equals(AGED_BRIE)) {
-                if (!item.name.equals("Backstage passes to a TAFKAL80ETC concert")) {
-                    if (item.quality > MIN_QUALITY) {
-                        if (!item.name.equals(SULFURAS)) {
-                            item.quality = item.quality - 1;
-                        }
-                    }
-                } else {
-                    item.quality = 0;
-                }
-            } else {
-                if (item.quality < MAX_QUALITY) {
-                    item.quality = item.quality + 1;
-                }
-            }
-        }
-    }
-
-    public static void validateItem(Item item) {
-        if (item.quality < GRItem.MIN_QUALITY) {
-            throw new ItemQualityIsNegativeException(item.name);
-        } else if (item.quality > GRItem.MAX_QUALITY && !item.name.equals(SULFURAS)) {
-            throw new ItemQualityExceedsMaxValueException(item.name);
-        }
-    }
-
-    @Override
-    public String toString() {
-        return "GRItem{" +
-                "item=" + item +
-                '}';
-    }
-}

Java/src/main/java/com/gildedrose/GildedRose.java

@@ -1,16 +1,19 @@
 package com.gildedrose;
 
+import com.gildedrose.item.GRItem;
+import com.gildedrose.item.GRItemFactory;
+
 import java.util.Arrays;
 
 class GildedRose {
+
     Item[] items;
 
     public GildedRose(Item[] items) {
-        Arrays.stream(items).forEach(GRItem::validateItem);
         this.items = items;
     }
 
     public void updateQuality() {
-        Arrays.stream(items).map(GRItem::new).forEach(GRItem::updateQuality);
+        Arrays.stream(items).map(GRItemFactory::create).forEach(GRItem::updateQuality);
     }
 }

Java/src/main/java/com/gildedrose/item/AgedBrieGRItem.java

@@ -0,0 +1,22 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+
+public class AgedBrieGRItem extends GRItem {
+
+    AgedBrieGRItem(Item item) {
+        super(item);
+    }
+
+    @Override
+    public void updateQuality() {
+        if (item.quality < MAX_QUALITY) {
+            item.quality = item.quality + 1;
+        }
+        item.sellIn = item.sellIn - 1;
+
+        if (item.quality < MAX_QUALITY && item.sellIn < 0) {
+            item.quality = item.quality + 1;
+        }
+    }
+}

Java/src/main/java/com/gildedrose/item/BackstagePassesGRItem.java

@@ -0,0 +1,35 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+
+public class BackstagePassesGRItem extends GRItem {
+
+    BackstagePassesGRItem(Item item) {
+        super(item);
+    }
+
+    @Override
+    public void updateQuality() {
+        if (item.quality < MAX_QUALITY) {
+            item.quality = item.quality + calculateQualityIncrement();
+        }
+
+        item.sellIn = item.sellIn - 1;
+
+        if (item.sellIn < 0) {
+            item.quality = MIN_QUALITY;
+        } else if (item.quality > MAX_QUALITY) {
+            item.quality = MAX_QUALITY;
+        }
+    }
+
+    private int calculateQualityIncrement() {
+        if (item.sellIn < 6) {
+            return 3;
+        } else if (item.sellIn < 11) {
+            return 2;
+        } else {
+            return 1;
+        }
+    }
+}

Java/src/main/java/com/gildedrose/item/ConjuredGRItem.java

@@ -0,0 +1,26 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+
+public class ConjuredGRItem extends GRItem {
+
+    public ConjuredGRItem(Item item) {
+        super(item);
+    }
+
+    @Override
+    public void updateQuality() {
+        if (item.quality > MIN_QUALITY) {
+            item.quality = item.quality - 2;
+        }
+        item.sellIn = item.sellIn - 1;
+
+        if (item.sellIn < 0 && item.quality > MIN_QUALITY) {
+            item.quality = item.quality - 2;
+        }
+
+        if (item.quality < MIN_QUALITY) {
+            item.quality = MIN_QUALITY;
+        }
+    }
+}

Java/src/main/java/com/gildedrose/item/GRItem.java

@@ -0,0 +1,28 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+
+import static com.gildedrose.item.GRItemFactory.SULFURAS;
+
+public abstract class GRItem {
+
+    protected static final int MAX_QUALITY = 50;
+    protected static final int MIN_QUALITY = 0;
+
+    protected final Item item;
+
+    GRItem(Item item) {
+        validateItem(item);
+        this.item = item;
+    }
+
+    public abstract void updateQuality();
+
+    private static void validateItem(Item item) {
+        if (item.quality < GRItem.MIN_QUALITY) {
+            throw new ItemQualityIsNegativeException(item.name);
+        } else if (item.quality > GRItem.MAX_QUALITY && !item.name.equals(SULFURAS)) {
+            throw new ItemQualityExceedsMaxValueException(item.name);
+        }
+    }
+}

Java/src/main/java/com/gildedrose/item/GRItemFactory.java

@@ -0,0 +1,40 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+
+public class GRItemFactory {
+    public static final String AGED_BRIE = "Aged Brie";
+    public static final String SULFURAS = "Sulfuras, Hand of Ragnaros";
+    public static final String BACKSTAGE_PASSES = "Backstage passes";
+    public static final String CONJURED = "Conjured";
+
+    public static GRItem create(Item item) {
+        if (isAgedBrie(item)) {
+            return new AgedBrieGRItem(item);
+        } else if (isBackstagePasses(item)) {
+            return new BackstagePassesGRItem(item);
+        } else if (isConjuredItem(item)) {
+            return new ConjuredGRItem(item);
+        } else if(isSulfuras(item)) {
+            return new SulfurasGRItem(item);
+        }
+        return new RegularGRItem(item);
+    }
+
+    private static boolean isSulfuras(Item item) {
+        return item.name.equals(SULFURAS);
+    }
+
+    private static boolean isConjuredItem(Item item) {
+        return item.name.startsWith(CONJURED);
+    }
+
+    private static boolean isBackstagePasses(Item item) {
+        return item.name.startsWith(BACKSTAGE_PASSES);
+    }
+
+    private static boolean isAgedBrie(Item item) {
+        return AGED_BRIE.equals(item.name);
+    }
+
+}

Java/src/main/java/com/gildedrose/item/ItemQualityExceedsMaxValueException.java

@@ -1,4 +1,4 @@
-package com.gildedrose;
+package com.gildedrose.item;
 
 public class ItemQualityExceedsMaxValueException extends RuntimeException {
 

Java/src/main/java/com/gildedrose/item/ItemQualityIsNegativeException.java

@@ -1,4 +1,4 @@
-package com.gildedrose;
+package com.gildedrose.item;
 
 public class ItemQualityIsNegativeException extends RuntimeException {
 

Java/src/main/java/com/gildedrose/item/RegularGRItem.java

@@ -0,0 +1,22 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+
+public class RegularGRItem extends GRItem {
+
+    RegularGRItem(Item item) {
+        super(item);
+    }
+
+    @Override
+    public void updateQuality() {
+        if (item.quality > MIN_QUALITY) {
+            item.quality = item.quality - 1;
+        }
+        item.sellIn = item.sellIn - 1;
+
+        if (item.sellIn < 0 && item.quality > MIN_QUALITY) {
+            item.quality = item.quality - 1;
+        }
+    }
+}

Java/src/main/java/com/gildedrose/item/SulfurasGRItem.java

@@ -0,0 +1,15 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+
+public class SulfurasGRItem extends GRItem {
+
+    public SulfurasGRItem(Item item) {
+        super(item);
+    }
+
+    @Override
+    public void updateQuality() {
+
+    }
+}

Java/src/test/java/com/gildedrose/GRItemConstructorTest.java

@@ -1,22 +0,0 @@
-package com.gildedrose;
-
-import org.junit.jupiter.api.Test;
-
-import static org.assertj.core.api.Assertions.assertThat;
-
-public class GRItemConstructorTest {
-
-    private static final String NAME = "+5 Dexterity Vest";
-    private static final int SELL_IN = 10;
-    private static final int QUALITY = 20;
-
-    @Test
-    public void constructsCorrectly() {
-        Item item = new Item(NAME, SELL_IN, QUALITY);
-        GRItem grItem = new GRItem(item);
-
-        assertThat(grItem.getName()).isEqualTo(NAME);
-        assertThat(grItem.getSellIn()).isEqualTo(SELL_IN);
-        assertThat(grItem.getQuality()).isEqualTo(QUALITY);
-    }
-}

Java/src/test/java/com/gildedrose/GRItemUpdateQualityTest.java

@@ -1,132 +0,0 @@
-package com.gildedrose;
-
-import org.junit.jupiter.api.Test;
-import org.junit.jupiter.params.ParameterizedTest;
-import org.junit.jupiter.params.provider.ValueSource;
-
-import static org.apache.commons.lang3.RandomStringUtils.random;
-import static org.assertj.core.api.Assertions.assertThat;
-
-public class GRItemUpdateQualityTest {
-    private static final String AGED_BRIE = "Aged Brie";
-    private static final String SULFURAS = "Sulfuras, Hand of Ragnaros";
-    private static final String BACKSTAGE_PASSES = "Backstage passes to a TAFKAL80ETC concert";
-    private static final String CONJURED = "Conjured Mana Cake";
-
-    @Test
-    public void lowersTheSellInValue() {
-        GRItem item = new GRItem(random(5), 10, 20);
-        item.updateQuality();
-
-        assertThat(item.getSellIn()).isEqualTo(9);
-    }
-
-    @Test
-    public void qualityDegrades() {
-        GRItem item = new GRItem(random(5), 10, 20);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(19);
-    }
-
-    @Test
-    public void qualityDegradesTwiceAsFastWhenSellByDatePassed() {
-        GRItem item = new GRItem(random(5), 0, 20);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(18);
-    }
-
-    @Test
-    public void qualityIsNeverNegative() {
-        GRItem item = new GRItem(random(5), 10, 0);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(0);
-    }
-
-    @Test
-    public void qualityOfAgedBrieIncreases() {
-        GRItem item = new GRItem(AGED_BRIE, 10, 10);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(11);
-    }
-
-    @Test
-    public void qualityOfAgedBrieIncreasesEvenWhenSellInIsNegative() {
-        GRItem item = new GRItem(AGED_BRIE, -1, 10);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(12);
-    }
-
-    @Test
-    public void qualityIncreasesNeverHigherThan50() {
-        GRItem item = new GRItem(AGED_BRIE, 10, 50);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(50);
-    }
-
-    @ParameterizedTest(name = "with quality {0}")
-    @ValueSource(ints = {-1, 0, 1, 20, 50})
-    public void qualityOfSulfurasNeverAlters(int quality) {
-        GRItem item = new GRItem(SULFURAS, 10, quality);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(quality);
-    }
-
-    @Test
-    public void sellInOfSulfurasNeverAlters() {
-        GRItem item = new GRItem(SULFURAS, 10, 20);
-        item.updateQuality();
-
-        assertThat(item.getSellIn()).isEqualTo(10);
-    }
-
-    @ParameterizedTest(name = "with sellIn {0}")
-    @ValueSource(ints = {10, 9, 8, 7, 6})
-    public void qualityOfBackstagePassesIncreaseBy2WhenSellIn10DaysOrLess(int sellIn) {
-        GRItem item = new GRItem(BACKSTAGE_PASSES, sellIn, 10);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(12);
-    }
-
-    @ParameterizedTest(name = "with sellIn {0}")
-    @ValueSource(ints = {5, 4, 3, 2, 1})
-    public void qualityOfBackstagePassesIncreaseBy3WhenSellIn5DaysOrLess(int sellIn) {
-        GRItem item = new GRItem(BACKSTAGE_PASSES, sellIn, 10);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(13);
-    }
-
-    @ParameterizedTest(name = "with sellIn {0}")
-    @ValueSource(ints = {0, -1})
-    public void qualityOfBackstagePassesIsZeroAfterConcert(int sellIn) {
-        GRItem item = new GRItem(BACKSTAGE_PASSES, sellIn, 10);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(0);
-    }
-
-    @Test
-    public void conjuredItemDegradesTwiceAsFast() {
-        GRItem item = new GRItem(CONJURED, 10, 10);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(8);
-    }
-
-    @ParameterizedTest(name = "with quality {0}")
-    @ValueSource(ints = {0, 1, 2})
-    public void conjuredItemDegradesNotBelow0(int quality) {
-        GRItem item = new GRItem(CONJURED, 10, quality);
-        item.updateQuality();
-
-        assertThat(item.getQuality()).isEqualTo(0);
-    }
-}

Java/src/test/java/com/gildedrose/GRItemValidateItemTest.java

@@ -1,33 +0,0 @@
-package com.gildedrose;
-
-import org.junit.jupiter.api.Test;
-
-import static org.apache.commons.lang3.RandomStringUtils.random;
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
-
-class GRItemValidateItemTest {
-
-    private static final String SULFURAS = "Sulfuras, Hand of Ragnaros";
-
-    @Test
-    public void throwsExceptionWhenItemValueIsNegative() {
-        Item item = new Item(random(5), 10, -1);
-
-        assertThatThrownBy(() -> GRItem.validateItem(item)).isInstanceOf(ItemQualityIsNegativeException.class);
-    }
-
-    @Test
-    public void throwsExceptionWhenItemValueExceedsMaxValue() {
-        Item item = new Item(random(5), 10, 51);
-
-        assertThatThrownBy(() -> GRItem.validateItem(item)).isInstanceOf(ItemQualityExceedsMaxValueException.class);
-    }
-
-
-    @Test
-    public void doesNotThrowExceptionWhenItemValueExceedsMaxValueAndItemIsSulfuras() {
-        Item item = new Item(SULFURAS, 10, 51);
-
-        GRItem.validateItem(item);
-    }
-}

Java/src/test/java/com/gildedrose/GuildedRoseConstructorTest.java

@@ -1,17 +0,0 @@
-package com.gildedrose;
-
-import org.junit.jupiter.api.Test;
-
-import static org.assertj.core.api.Assertions.assertThatThrownBy;
-
-public class GuildedRoseConstructorTest {
-
-    @Test
-    public void validatesInitialItemQualities() {
-        Item[] items = new Item[]{
-                new Item("+5 Dexterity Vest", 10, -1)
-        };
-
-        assertThatThrownBy(() -> new GildedRose(items)).isInstanceOf(ItemQualityIsNegativeException.class);
-    }
-}

Java/src/test/java/com/gildedrose/item/AgedBrieGRItemUpdateQualityTest.java

@@ -0,0 +1,49 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+import com.gildedrose.item.GRItem;
+import com.gildedrose.item.GRItemFactory;
+import org.junit.jupiter.api.Test;
+
+import static com.gildedrose.item.GRItemFactory.AGED_BRIE;
+import static org.apache.commons.lang3.RandomStringUtils.random;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class AgedBrieGRItemUpdateQualityTest {
+
+    @Test
+    public void lowersTheSellInValue() {
+        Item item = new Item(random(5), 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.sellIn).isEqualTo(9);
+    }
+
+    @Test
+    public void qualityOfAgedBrieIncreases() {
+        Item item = new Item(AGED_BRIE, 10, 10);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(11);
+    }
+
+    @Test
+    public void qualityOfAgedBrieIncreasesDoubleFastWhenSellInIsNegative() {
+        Item item = new Item(AGED_BRIE, -1, 10);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(12);
+    }
+
+    @Test
+    public void qualityIncreasesNeverHigherThan50() {
+        Item item = new Item(AGED_BRIE, 10, 50);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(50);
+    }
+}

Java/src/test/java/com/gildedrose/item/BackstagePassesGRItemUpdateQualityTest.java

@@ -0,0 +1,74 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static com.gildedrose.item.GRItemFactory.BACKSTAGE_PASSES;
+import static org.apache.commons.lang3.RandomStringUtils.random;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class BackstagePassesGRItemUpdateQualityTest {
+
+    private static final String BACKSTAGE_PASSES_RANDOM = BACKSTAGE_PASSES + " " + random(5);
+
+    @Test
+    public void lowersTheSellInValue() {
+        Item item = new Item(BACKSTAGE_PASSES_RANDOM, 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.sellIn).isEqualTo(9);
+    }
+
+    @Test
+    public void qualityOfBackstagePassesIncreaseBy1WhenSellInisHigherThan10() {
+        Item item = new Item(BACKSTAGE_PASSES_RANDOM, 11, 10);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(11);
+    }
+
+    @ParameterizedTest(name = "with sellIn {0}")
+    @ValueSource(ints = {10, 9, 8, 7, 6})
+    public void qualityOfBackstagePassesIncreaseBy2WhenSellIn10DaysOrLess(int sellIn) {
+        Item item = new Item(BACKSTAGE_PASSES_RANDOM, sellIn, 10);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(12);
+    }
+
+    @ParameterizedTest(name = "with sellIn {0}")
+    @ValueSource(ints = {5, 4, 3, 2, 1})
+    public void qualityOfBackstagePassesIncreaseBy3WhenSellIn5DaysOrLess(int sellIn) {
+        Item item = new Item(BACKSTAGE_PASSES_RANDOM, sellIn, 10);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(13);
+    }
+
+    @ParameterizedTest(name = "with sellIn {0}")
+    @ValueSource(ints = {0, -1})
+    public void qualityOfBackstagePassesIsZeroAfterConcert(int sellIn) {
+        Item item = new Item(BACKSTAGE_PASSES_RANDOM, sellIn, 10);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(0);
+    }
+
+    @ParameterizedTest(name = "with sellIn {0}")
+    @ValueSource(ints = {15, 9, 3})
+    public void qualityOfBackstagePassesNeverIncreasesAboveMax(int sellIn) {
+        Item item = new Item(BACKSTAGE_PASSES_RANDOM, sellIn, 49);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(50);
+    }
+
+}

Java/src/test/java/com/gildedrose/item/ConjuredGRItemUpdateQualityTest.java

@@ -0,0 +1,55 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+import com.gildedrose.item.GRItem;
+import com.gildedrose.item.GRItemFactory;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static com.gildedrose.item.GRItemFactory.CONJURED;
+import static org.apache.commons.lang3.RandomStringUtils.random;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class ConjuredGRItemUpdateQualityTest {
+
+    private static final String CONJURED_STUFF = CONJURED + " Stuff";
+
+    @Test
+    public void lowersTheSellInValue() {
+        Item item = new Item(CONJURED_STUFF, 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.sellIn).isEqualTo(9);
+    }
+
+    @Test
+    public void qualityDegradesBy2() {
+        Item item = new Item(CONJURED_STUFF, 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(18);
+    }
+
+    @Test
+    public void qualityDegradesTwiceAsFastWhenSellByDatePassed() {
+        Item item = new Item(CONJURED_STUFF, 0, 20);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(16);
+    }
+
+    @ParameterizedTest(name = "with quality {0}")
+    @ValueSource(ints = {0, 1, 2})
+    public void conjuredItemDegradesNotBelow0(int quality) {
+        Item item = new Item(CONJURED_STUFF, 10, quality);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(0);
+    }
+
+}

Java/src/test/java/com/gildedrose/item/GRItemFactoryCreateTest.java

@@ -0,0 +1,52 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+import com.gildedrose.item.*;
+import org.junit.jupiter.api.Test;
+
+import static com.gildedrose.item.GRItemFactory.*;
+import static org.apache.commons.lang3.RandomStringUtils.random;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class GRItemFactoryCreateTest {
+
+    @Test
+    public void createsRegularGRItem() {
+        Item item = new Item(random(5), 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+
+        assertThat(grItem).isInstanceOf(RegularGRItem.class);
+    }
+
+    @Test
+    public void createsConjuredGRItem() {
+        Item item = new Item(CONJURED + " " + random(5), 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+
+        assertThat(grItem).isInstanceOf(ConjuredGRItem.class);
+    }
+
+    @Test
+    public void createsBackstagePassesGRItem() {
+        Item item = new Item(BACKSTAGE_PASSES + " " + random(5), 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+
+        assertThat(grItem).isInstanceOf(BackstagePassesGRItem.class);
+    }
+
+    @Test
+    public void createsAgedBrieGRItem() {
+        Item item = new Item(AGED_BRIE, 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+
+        assertThat(grItem).isInstanceOf(AgedBrieGRItem.class);
+    }
+
+    @Test
+    public void createsSulfurasGRItem() {
+        Item item = new Item(SULFURAS, 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+
+        assertThat(grItem).isInstanceOf(SulfurasGRItem.class);
+    }
+}

Java/src/test/java/com/gildedrose/item/GRItemValidateItemTest.java

@@ -0,0 +1,35 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+import org.junit.jupiter.api.Test;
+
+import static org.apache.commons.lang3.RandomStringUtils.random;
+import static org.apache.commons.lang3.RandomUtils.nextInt;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+class GRItemValidateItemTest {
+
+    private static final String SULFURAS = "Sulfuras, Hand of Ragnaros";
+
+    @Test
+    public void throwsExceptionWhenItemValueIsNegative() {
+        Item item = new Item(random(5), nextInt(0, 10), -1);
+
+        assertThatThrownBy(() -> GRItemFactory.create(item)).isInstanceOf(ItemQualityIsNegativeException.class);
+    }
+
+    @Test
+    public void throwsExceptionWhenItemValueExceedsMaxValue() {
+        Item item = new Item(random(5), nextInt(0, 10), 51);
+
+        assertThatThrownBy(() -> GRItemFactory.create(item)).isInstanceOf(ItemQualityExceedsMaxValueException.class);
+    }
+
+
+    @Test
+    public void doesNotThrowExceptionWhenItemValueExceedsMaxValueAndItemIsSulfuras() {
+        Item item = new Item(SULFURAS, nextInt(0, 10), 51);
+
+        GRItemFactory.create(item);
+    }
+}

Java/src/test/java/com/gildedrose/item/RegularGRItemUpdateQualityTest.java

@@ -0,0 +1,49 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+import com.gildedrose.item.GRItem;
+import com.gildedrose.item.GRItemFactory;
+import org.junit.jupiter.api.Test;
+
+import static org.apache.commons.lang3.RandomStringUtils.random;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class RegularGRItemUpdateQualityTest {
+
+    @Test
+    public void lowersTheSellInValue() {
+        Item item = new Item(random(5), 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.sellIn).isEqualTo(9);
+    }
+
+    @Test
+    public void qualityDegradesBy1() {
+        Item item = new Item(random(5), 10, 20);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(19);
+    }
+
+    @Test
+    public void qualityDegradesTwiceAsFastWhenSellByDatePassed() {
+        Item item = new Item(random(5), 0, 20);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(18);
+    }
+
+    @Test
+    public void qualityIsNeverNegative() {
+        Item item = new Item(random(5), 10, 0);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.quality).isEqualTo(0);
+    }
+
+}

Java/src/test/java/com/gildedrose/item/SulfurasGRItemUpdateQualityTest.java

@@ -0,0 +1,25 @@
+package com.gildedrose.item;
+
+import com.gildedrose.Item;
+import com.gildedrose.item.GRItem;
+import com.gildedrose.item.GRItemFactory;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.ValueSource;
+
+import static com.gildedrose.item.GRItemFactory.SULFURAS;
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class SulfurasGRItemUpdateQualityTest {
+
+    @ParameterizedTest(name = "with quality {0}")
+    @ValueSource(ints = {0, 1, 20, 50})
+    public void doesNothing(int quality) {
+        Item item = new Item(SULFURAS, 10, quality);
+        GRItem grItem = GRItemFactory.create(item);
+        grItem.updateQuality();
+
+        assertThat(item.sellIn).isEqualTo(10);
+        assertThat(item.quality).isEqualTo(quality);
+    }
+}
+