Refactored quality update using strategy and factory patterns

Java/build.gradle

@@ -11,6 +11,7 @@ dependencies {
     testImplementation 'org.junit.jupiter:junit-jupiter-params:5.7.0'
     testImplementation 'org.junit.jupiter:junit-jupiter-engine:5.7.0'
     testImplementation 'com.approvaltests:approvaltests:9.3.0'
+    testCompile group: 'org.assertj', name: 'assertj-core', version: '3.17.2'
 }
 
 group = 'com.gildedrose'

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

@@ -0,0 +1,26 @@
+package com.gildedrose;
+
+public class AgedBrieQualityUpdater implements ItemQualityUpdater {
+
+   private final Item item;
+
+   public AgedBrieQualityUpdater(Item item) {
+      this.item = item;
+   }
+
+   @Override
+   public void updateQuality() {
+      if (item.quality < 50) {
+         item.quality = item.quality + 1;
+      }
+
+      item.sellIn = item.sellIn - 1;
+
+      if (item.sellIn < 0) {
+         if (item.quality < 50) {
+            item.quality = item.quality + 1;
+         }
+      }
+
+   }
+}

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

@@ -0,0 +1,36 @@
+package com.gildedrose;
+
+public class BackstageBrieQualityUpdater implements ItemQualityUpdater {
+
+   private final Item item;
+
+   public BackstageBrieQualityUpdater(Item item) {
+      this.item = item;
+   }
+
+   @Override
+   public void updateQuality() {
+      if (item.quality < 50) {
+         item.quality = item.quality + 1;
+
+         if (item.sellIn < 11) {
+            if (item.quality < 50) {
+               item.quality = item.quality + 1;
+            }
+         }
+
+         if (item.sellIn < 6) {
+            if (item.quality < 50) {
+               item.quality = item.quality + 1;
+            }
+         }
+      }
+
+      item.sellIn = item.sellIn - 1;
+
+      if (item.sellIn < 0) {
+         item.quality = 0;
+      }
+
+   }
+}

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

@@ -0,0 +1,25 @@
+package com.gildedrose;
+
+public class DefaultQualityUpdater implements ItemQualityUpdater {
+
+   private final Item item;
+
+   public DefaultQualityUpdater(Item item) {
+      this.item = item;
+   }
+
+   @Override
+   public void updateQuality() {
+      if (item.quality > 0) {
+         item.quality = item.quality - 1;
+      }
+
+      item.sellIn = item.sellIn - 1;
+
+      if (item.sellIn < 0) {
+         if (item.quality > 0) {
+            item.quality = item.quality - 1;
+         }
+      }
+   }
+}

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

@@ -1,62 +1,23 @@
 package com.gildedrose;
 
+import static com.gildedrose.ItemQualityUpdateStrategyFactory.itemQualityUpdaterFor;
+
+import java.util.Arrays;
+
 class GildedRose {
-    Item[] items;
 
-    public GildedRose(Item[] items) {
+   Item[] items;
-        this.items = items;
-    }
 
-    public void updateQuality() {
+   public GildedRose(Item[] items) {
-        for (int i = 0; i < items.length; i++) {
+      this.items = items;
-            if (!items[i].name.equals("Aged Brie")
+   }
-                    && !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 {
-                if (items[i].quality < 50) {
-                    items[i].quality = items[i].quality + 1;
 
-                    if (items[i].name.equals("Backstage passes to a TAFKAL80ETC concert")) {
+   public void updateQuality() {
-                        if (items[i].sellIn < 11) {
+      Arrays.stream(items).forEach(this::updateQuality);
-                            if (items[i].quality < 50) {
+   }
-                                items[i].quality = items[i].quality + 1;
-                            }
-                        }
 
-                        if (items[i].sellIn < 6) {
+   private void updateQuality(Item item) {
-                            if (items[i].quality < 50) {
+      itemQualityUpdaterFor(item).updateQuality();
-                                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/ItemQualityUpdateStrategyFactory.java

@@ -0,0 +1,12 @@
+package com.gildedrose;
+
+public class ItemQualityUpdateStrategyFactory {
+   public static ItemQualityUpdater itemQualityUpdaterFor(Item item) {
+      switch (item.name) {
+         case "Sulfuras, Hand of Ragnaros": return new SulfrasQualityUpdater(item);
+         case "Aged Brie": return new AgedBrieQualityUpdater(item);
+         case "Backstage passes to a TAFKAL80ETC concert": return new BackstageBrieQualityUpdater(item);
+         default: return new DefaultQualityUpdater(item);
+      }
+   }
+}

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

@@ -0,0 +1,5 @@
+package com.gildedrose;
+
+public interface ItemQualityUpdater {
+   void updateQuality();
+}

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

@@ -0,0 +1,13 @@
+package com.gildedrose;
+
+public class SulfrasQualityUpdater implements ItemQualityUpdater {
+
+   private final Item item;
+
+   public SulfrasQualityUpdater(Item item) {
+      this.item = item;
+   }
+
+   public void updateQuality() {
+   }
+}

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

@@ -0,0 +1,23 @@
+package com.gildedrose;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.Test;
+
+class ItemQualityUpdateStrategyFactoryTest {
+
+   @Test
+   void itemQualityUpdaterFor() {
+      testFactoryFor("Sulfuras, Hand of Ragnaros", SulfrasQualityUpdater.class);
+      testFactoryFor("Aged Brie", AgedBrieQualityUpdater.class);
+      testFactoryFor("Backstage passes to a TAFKAL80ETC concert", BackstageBrieQualityUpdater.class);
+      testFactoryFor("xyz", DefaultQualityUpdater.class);
+   }
+
+   void testFactoryFor(String name, Class<? extends ItemQualityUpdater> clazz) {
+      ItemQualityUpdater qualityUpdater = ItemQualityUpdateStrategyFactory
+          .itemQualityUpdaterFor(new Item(name, 0, 0));
+      assertThat(qualityUpdater).isInstanceOf(clazz);
+   }
+
+}