refactor: simplify updateItem and add param tests

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

@@ -1,5 +1,7 @@
 package com.gildedrose;
 
+import java.util.Objects;
+
 import static com.gildedrose.ItemType.fromName;
 
 public class Item {
@@ -24,17 +26,26 @@ public class Item {
     }
 
     public void updateItem() {
-        boolean isAgedBrie = name.equals("Aged Brie");
-        boolean isSulfuras = name.equals("Sulfuras, Hand of Ragnaros");
-        boolean isBackStagePass = name.equals("Backstage passes to a TAFKAL80ETC concert");
+        switch (type) {
+            case AgedBrie -> {
 
-        if (!isAgedBrie && !isBackStagePass) {
-            if (quality > 0 && !isSulfuras) {
-                deductOneFromQuality();
+                if (quality < 50) {
+                    addOneToQuality();
+                }
+
+                deductSellIn();
+
+                if (sellIn < 0 && quality < 50) {
+                    addOneToQuality();
+                }
             }
-        } else if(quality < 50) {
-            addOneToQuality();
-            if (isBackStagePass) {
+
+            case BackstagePass -> {
+
+                if (quality < 50) {
+                    addOneToQuality();
+                }
+
                 if (sellIn < 11 && quality < 50) {
                     addOneToQuality();
                 }
@@ -42,24 +53,26 @@ public class Item {
                 if (sellIn < 6 && quality < 50) {
                     addOneToQuality();
                 }
-            }
-        }
+                deductSellIn();
 
-        if (!isSulfuras) {
-            deductSellIn();
-        }
 
-        if (sellIn < 0) {
-            if (!isAgedBrie) {
-                if (!isBackStagePass) {
-                    if (quality > 0 && !isSulfuras) {
-                        deductOneFromQuality();
-                    }
-                } else {
-                    setQualityToZero();
+                if (sellIn < 0) {
+                    quality = 0;
+                }
+            }
+
+            case Sulfuras -> {}
+
+            case Unknown -> {
+                deductSellIn();
+
+                if (quality > 0) {
+                    deductOneFromQuality();
+                }
+
+                if (sellIn < 0 && quality > 0) {
+                    deductOneFromQuality();
                 }
-            } else if ((quality < 50)) {
-                addOneToQuality();
             }
         }
     }

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

@@ -0,0 +1,60 @@
+package com.gildedrose;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.util.stream.Stream;
+
+import static com.gildedrose.ItemType.AgedBrie;
+import static com.gildedrose.ItemType.BackstagePass;
+import static com.gildedrose.ItemType.Sulfuras;
+import static com.gildedrose.ItemType.Unknown;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.params.provider.Arguments.of;
+
+class ItemTest {
+
+    @ParameterizedTest
+    @MethodSource("provideAgedBrieOptions")
+    void givenAgedBrie_whenUpdateItem_thenCorrect(Item input, Item expected, int days) {
+
+        for (int i = 0; i < days; i++) {
+            input.updateItem();
+        }
+
+        assertEquals(expected, input);
+    }
+
+    private static Stream<Arguments> provideAgedBrieOptions() {
+        return Stream.of(
+
+            // Aged Brie
+            of(new Item(AgedBrie.getName(), -1, 0), new Item(AgedBrie.getName(), -2, 2), 1),
+            of(new Item(AgedBrie.getName(), 100, 0), new Item(AgedBrie.getName(), 0, 50), 100),
+            of(new Item(AgedBrie.getName(), 50, 0), new Item(AgedBrie.getName(), 40, 10), 10),
+            of(new Item(AgedBrie.getName(), 50, 0), new Item(AgedBrie.getName(), 20, 30), 30),
+
+            // Sulfuras -- no changes with sulfuras
+            of(new Item(Sulfuras.getName(), -1, 0), new Item(Sulfuras.getName(), -1, 0), 1),
+            of(new Item(Sulfuras.getName(), 10, 0), new Item(Sulfuras.getName(), 10, 0), 1),
+            of(new Item(Sulfuras.getName(), 100, 0), new Item(Sulfuras.getName(), 100, 0), 10),
+            of(new Item(Sulfuras.getName(), 10, 20), new Item(Sulfuras.getName(), 10, 20), 10),
+            of(new Item(Sulfuras.getName(), 4, 20), new Item(Sulfuras.getName(), 4, 20), 10),
+
+            // Backstagepass
+            of(new Item(BackstagePass.getName(), 8, 40), new Item(BackstagePass.getName(), 7, 42), 1),
+            of(new Item(BackstagePass.getName(), 8, 40), new Item(BackstagePass.getName(), -2, 0), 10),
+            of(new Item(BackstagePass.getName(), 4, 40), new Item(BackstagePass.getName(), -6, 0), 10),
+            of(new Item(BackstagePass.getName(), 0, 40), new Item(BackstagePass.getName(), -10, 0), 10),
+            of(new Item(BackstagePass.getName(), -1, 40), new Item(BackstagePass.getName(), -11, 0), 10),
+
+            // Other
+            of(new Item(Unknown.getName(), 0, 40), new Item(Unknown.getName(), -10, 20), 10),
+            of(new Item(Unknown.getName(), -1, 40), new Item(Unknown.getName(), -11, 20), 10),
+            of(new Item(Unknown.getName(), -5, 80), new Item(Unknown.getName(), -25, 40), 20)
+
+        );
+    }
+}