Refactor: Implement Strategy pattern for item updaters

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

@@ -0,0 +1,14 @@
+package com.gildedrose;
+
+public class AgedBrieUpdater extends BaseItemUpdater {
+
+    @Override
+    public void update(Item item) {
+        decreaseSellIn(item);
+        if (item.sellIn < 0) {
+            increaseQuality(item , 2);
+        }
+        else
+            increaseQuality(item);
+    }
+}

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

@@ -0,0 +1,20 @@
+package com.gildedrose;
+
+public class BackstagePassUpdater extends  BaseItemUpdater{
+    @Override
+    public void update(Item item) {
+       decreaseSellIn(item);
+        if (item.sellIn <0) {
+            item.quality = 0;
+            return;
+        }
+        if (item.sellIn <= 5) {
+            increaseQuality(item , 3);
+        }
+        else if (item.sellIn <= 10) {
+            increaseQuality(item , 2);
+        }
+        else
+            increaseQuality(item);
+    }
+}

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

@@ -0,0 +1,22 @@
+package com.gildedrose;
+
+public  abstract class BaseItemUpdater implements ItemUpdater {
+
+    public abstract void update(Item item);
+    protected void decreaseQuality(Item item) {
+        item.quality = Math.max(item.quality - 1, 0);
+    }
+    protected void decreaseQuality(Item item , int amount) {
+        item.quality = Math.max(0, item.quality - amount);
+    }
+    protected void  increaseQuality(Item item) {
+        item.quality = Math.min(item.quality + 1, 50);
+    }
+    protected void increaseQuality(Item item , int amount) {
+        item.quality = Math.min(item.quality + amount, 50);
+    }
+    protected void decreaseSellIn(Item item) {
+       item.sellIn--;
+    }
+
+}

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

@@ -0,0 +1,12 @@
+package com.gildedrose;
+
+public class ConjuredItemUpdater extends  BaseItemUpdater {
+    @Override
+    public void update(Item item) {
+        decreaseSellIn(item);
+        if (item.sellIn < 0) {
+            decreaseQuality(item, 4);
+        }
+        else decreaseQuality(item, 2);
+    }
+}

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

@@ -1,62 +1,14 @@
 package com.gildedrose;
-
+public class GildedRose {
-class GildedRose {
+   public Item[] items;
-    Item[] items;
-
     public GildedRose(Item[] items) {
         this.items = items;
     }
 
     public void updateQuality() {
-        for (int i = 0; i < items.length; i++) {
+        for (Item item : items) {
-            if (!items[i].name.equals("Aged Brie")
+         ItemUpdater updater = ItemUpdaterFactory.getItemUpdater(item);
-                    && !items[i].name.equals("Backstage passes to a TAFKAL80ETC concert")) {
+         updater.update(item);
-                if (items[i].quality > 0) {
-                    if (!items[i].name.equals("Sulfuras, Hand of Ragnaros")) {
-                        items[i].quality = items[i].quality - 1;
-                    }
-                }
-            } else {
-                if (items[i].quality < 50) {
-                    items[i].quality = items[i].quality + 1;
-
-                    if (items[i].name.equals("Backstage passes to a TAFKAL80ETC concert")) {
-                        if (items[i].sellIn < 11) {
-                            if (items[i].quality < 50) {
-                                items[i].quality = items[i].quality + 1;
-                            }
-                        }
-
-                        if (items[i].sellIn < 6) {
-                            if (items[i].quality < 50) {
-                                items[i].quality = items[i].quality + 1;
-                            }
-                        }
-                    }
-                }
-            }
-
-            if (!items[i].name.equals("Sulfuras, Hand of Ragnaros")) {
-                items[i].sellIn = items[i].sellIn - 1;
-            }
-
-            if (items[i].sellIn < 0) {
-                if (!items[i].name.equals("Aged Brie")) {
-                    if (!items[i].name.equals("Backstage passes to a TAFKAL80ETC concert")) {
-                        if (items[i].quality > 0) {
-                            if (!items[i].name.equals("Sulfuras, Hand of Ragnaros")) {
-                                items[i].quality = items[i].quality - 1;
-                            }
-                        }
-                    } else {
-                        items[i].quality = items[i].quality - items[i].quality;
-                    }
-                } else {
-                    if (items[i].quality < 50) {
-                        items[i].quality = items[i].quality + 1;
-                    }
-                }
-            }
         }
     }
 }

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

@@ -0,0 +1,5 @@
+package com.gildedrose;
+
+public interface ItemUpdater {
+     void update(Item item);
+}

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

@@ -0,0 +1,19 @@
+package com.gildedrose;
+
+public class ItemUpdaterFactory {
+    public static ItemUpdater getItemUpdater(Item item) {
+        if (item.name.contains("Aged Brie"))
+            return new AgedBrieUpdater();
+
+        if (item.name.contains("Sulfuras"))
+            return new SulfurasUpdater();
+
+        if (item.name.contains("Backstage"))
+            return new BackstagePassUpdater();
+
+        if (item.name.contains("Conjured"))
+            return new ConjuredItemUpdater();
+
+        return new NormalItemUpdater();
+    }
+}

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

@@ -0,0 +1,14 @@
+package com.gildedrose;
+
+public class NormalItemUpdater extends BaseItemUpdater {
+    @Override
+    public void update(Item item) {
+        decreaseSellIn(item);
+        if (item.sellIn <0) {
+            decreaseQuality(item, 2);
+        }
+        else {
+            decreaseQuality(item);
+        }
+    }
+}

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

@@ -0,0 +1,8 @@
+package com.gildedrose;
+
+public class SulfurasUpdater extends  BaseItemUpdater {
+    @Override
+    public void update(Item item) {
+        System.out.println("Legendary Item can not be updated");
+    }
+}

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

@@ -1,17 +1,52 @@
 package com.gildedrose;
 
 import org.junit.jupiter.api.Test;
-
 import static org.junit.jupiter.api.Assertions.assertEquals;
 
 class GildedRoseTest {
 
     @Test
-    void foo() {
+    void normalItemDegrades() {
-        Item[] items = new Item[] { new Item("foo", 0, 0) };
+        Item[] items = new Item[] { new Item("Normal Item", 10, 20) };
         GildedRose app = new GildedRose(items);
         app.updateQuality();
-        assertEquals("fixme", app.items[0].name);
+        assertEquals(9, app.items[0].sellIn);
+        assertEquals(19, app.items[0].quality);
     }
 
+    @Test
+    void agedBrieIncreasesQuality() {
+        Item[] items = new Item[] { new Item("Aged Brie", 10, 20) };
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+        assertEquals(9, app.items[0].sellIn);
+        assertEquals(21, app.items[0].quality);
+    }
+
+    @Test
+    void sulfurasNeverChanges() {
+        Item[] items = new Item[] { new Item("Sulfuras, Hand of Ragnaros", 10, 80) };
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+        assertEquals(10, app.items[0].sellIn);
+        assertEquals(80, app.items[0].quality);
+    }
+
+    @Test
+    void backstagePassIncreasesQualityNearConcert() {
+        Item[] items = new Item[] { new Item("Backstage passes to a TAFKAL80ETC concert", 5, 20) };
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+        assertEquals(4, app.items[0].sellIn);
+        assertEquals(23, app.items[0].quality); // +3 when 5 days or less
+    }
+
+    @Test
+    void conjuredItemDegradesTwiceAsFast() {
+        Item[] items = new Item[] { new Item("Conjured Mana Cake", 10, 20) };
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+        assertEquals(9, app.items[0].sellIn);
+        assertEquals(18, app.items[0].quality); // -2 instead of -1
+    }
 }

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

@@ -1,10 +1,9 @@
 package com.gildedrose;
-
 public class TexttestFixture {
     public static void main(String[] args) {
         System.out.println("OMGHAI!");
 
-        Item[] items = new Item[] {
+       Item [] items = new Item[] {
                 new Item("+5 Dexterity Vest", 10, 20), //
                 new Item("Aged Brie", 2, 0), //
                 new Item("Elixir of the Mongoose", 5, 7), //