diff --git a/Java/src/main/java/com/gildedrose/GildedRose.java b/Java/src/main/java/com/gildedrose/GildedRose.java
index 88a3cb82..627e753a 100644
--- a/Java/src/main/java/com/gildedrose/GildedRose.java
+++ b/Java/src/main/java/com/gildedrose/GildedRose.java
@@ -5,11 +5,13 @@ class GildedRose {
     public static final String AGED_BRIE = "Aged Brie";
     public static final String BACKSTAGE_PASSES = "Backstage passes to a TAFKAL80ETC concert";
     public static final String SULFURAS = "Sulfuras, Hand of Ragnaros";
-    public static final int QUALITY_LEVEL_0 = 0;
-    public static final int QUALITY_LEVEL_50 = 50;
+
+    public static final int MINIMUM_QUALITY = 0;
+    public static final int MAXIMUM_QUALITY = 50;
+
     public static final int SELL_IN_DAY11 = 11;
     public static final int SELL_IN_DAY6 = 6;
-    public static final int SELL_IN_DAY0 = 0;
+    public static final int SELL_IN_EXPIRED = 0;
 
     Item[] items;
 
@@ -31,65 +33,81 @@ class GildedRose {
 
         if (isAgedBrie) {
             // processing quality
-            if (item.quality < QUALITY_LEVEL_50) {
-                item.quality = item.quality + 1;
+            if (item.quality < MAXIMUM_QUALITY) {
+                increaseQuality(item);
             }
 
             // processing sell date
-            item.sellIn = item.sellIn - 1;
+            decreaseDay(item);
 
             // processing sell date
-            if (item.sellIn < SELL_IN_DAY0) {
-                if (item.quality < QUALITY_LEVEL_50) {
-                    item.quality = item.quality + 1;
+            if (isExpired(item)) {
+                if (item.quality < MAXIMUM_QUALITY) {
+                    increaseQuality(item);
                 }
             }
         } else if (isBackstagePasses) {
             // processing quality
-            if (item.quality < QUALITY_LEVEL_50) {
-                item.quality = item.quality + 1;
+            if (item.quality < MAXIMUM_QUALITY) {
+                increaseQuality(item);
 
                 // processing sell date
                 if (item.sellIn < SELL_IN_DAY11) {
-                    if (item.quality < QUALITY_LEVEL_50) {
-                        item.quality = item.quality + 1;
+                    if (item.quality < MAXIMUM_QUALITY) {
+                        increaseQuality(item);
                     }
                 }
 
                 if (item.sellIn < SELL_IN_DAY6) {
-                    if (item.quality < QUALITY_LEVEL_50) {
-                        item.quality = item.quality + 1;
+                    if (item.quality < MAXIMUM_QUALITY) {
+                        increaseQuality(item);
                     }
                 }
             }
 
             // processing sell date
-            item.sellIn = item.sellIn - 1;
+            decreaseDay(item);
 
             // processing sell date
-            if (item.sellIn < SELL_IN_DAY0) {
-                item.quality = QUALITY_LEVEL_0;
+            if (isExpired(item)) {
+                item.quality = MINIMUM_QUALITY;
             }
         } else if (isSulfuras) {
             //sulfuras is doing nothing
 
         } else {
             //standard item
-            if (item.quality > QUALITY_LEVEL_0) {
-                item.quality = item.quality - 1;
+            if (item.quality > MINIMUM_QUALITY) {
+                decreaseQuality(item);
             }
 
             // processing sell date
-            item.sellIn = item.sellIn - 1;
+            decreaseDay(item);
 
             // processing sell date
-            if (item.sellIn < SELL_IN_DAY0) {
+            if (isExpired(item)) {
                 // processing quality
-                if (item.quality > QUALITY_LEVEL_0) {
-                    item.quality = item.quality - 1;
+                if (item.quality > MINIMUM_QUALITY) {
+                    decreaseQuality(item);
                 }
             }
         }
     }
 
+    private static void decreaseDay(Item item) {
+        item.sellIn = item.sellIn - 1;
+    }
+
+    private static boolean isExpired(Item item) {
+        return item.sellIn < SELL_IN_EXPIRED;
+    }
+
+    private static void decreaseQuality(Item item) {
+        item.quality = item.quality - 1;
+    }
+
+    private static void increaseQuality(Item item) {
+        item.quality = item.quality + 1;
+    }
+
 }
diff --git a/Java/src/test/java/com/gildedrose/AgedBrieTest.java b/Java/src/test/java/com/gildedrose/AgedBrieTest.java
new file mode 100644
index 00000000..8f7e61a7
--- /dev/null
+++ b/Java/src/test/java/com/gildedrose/AgedBrieTest.java
@@ -0,0 +1,24 @@
+package com.gildedrose;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class AgedBrieTest {
+
+    @Test
+    void agedBrieQualityIncreasesByOne() {
+        //given
+        Item agedBrie = new Item("Aged Brie", 5, 2);
+        Item[] items = new Item[] {agedBrie};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(4, app.items[0].sellIn);
+        assertEquals(3, app.items[0].quality);
+    }
+
+}
diff --git a/Java/src/test/java/com/gildedrose/BackStageTest.java b/Java/src/test/java/com/gildedrose/BackStageTest.java
new file mode 100644
index 00000000..09e12dc2
--- /dev/null
+++ b/Java/src/test/java/com/gildedrose/BackStageTest.java
@@ -0,0 +1,61 @@
+package com.gildedrose;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class BackStageTest {
+
+    @Test
+    void backStageQualityIncreasesByTwoWhenThereAre10DaysOrLess() {
+        //given
+        Item backStage10 = new Item("Backstage passes to a TAFKAL80ETC concert", 10, 2);
+        Item backStage6 = new Item("Backstage passes to a TAFKAL80ETC concert", 6, 2);
+        Item[] items = new Item[] {backStage10, backStage6};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(9, app.items[0].sellIn);
+        assertEquals(4, app.items[0].quality);
+
+        assertEquals(5, app.items[1].sellIn);
+        assertEquals(4, app.items[1].quality);
+    }
+
+    @Test
+    void backStageQualityIncreasesByThreeWhenThereAre5DaysOrLess() {
+        //given
+        Item backStage5 = new Item("Backstage passes to a TAFKAL80ETC concert", 5, 3);
+        Item backStage4 = new Item("Backstage passes to a TAFKAL80ETC concert", 4, 3);
+        Item[] items = new Item[] {backStage5, backStage4};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(4, app.items[0].sellIn);
+        assertEquals(6, app.items[0].quality);
+
+        assertEquals(3, app.items[1].sellIn);
+        assertEquals(6, app.items[1].quality);
+    }
+
+    @Test
+    void backStageQualityDecreasesToZeroWhenIsExpired() {
+        //given
+        Item backStage = new Item("Backstage passes to a TAFKAL80ETC concert", 0, 3);
+        Item[] items = new Item[] {backStage};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(-1, app.items[0].sellIn);
+        assertEquals(0, app.items[0].quality);
+    }
+}
diff --git a/Java/src/test/java/com/gildedrose/GildedRoseTest.java b/Java/src/test/java/com/gildedrose/GildedRoseTest.java
index 7c5fc0a2..291f717c 100644
--- a/Java/src/test/java/com/gildedrose/GildedRoseTest.java
+++ b/Java/src/test/java/com/gildedrose/GildedRoseTest.java
@@ -6,12 +6,65 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 
 class GildedRoseTest {
 
+    //GENERAL RULES
     @Test
-    void foo() {
-        Item[] items = new Item[] { new Item("foo", 0, 0) };
+    void whenSellInDateIsPassed_qualityDegradesTwiceAsFast() {
+        //given
+        Item testItem = new Item("standard item", 0, 3);
+        Item[] items = new Item[] {testItem};
+
+        //when
         GildedRose app = new GildedRose(items);
         app.updateQuality();
-        assertEquals("foo", app.items[0].name);
+
+        //then
+        assertEquals(-1, app.items[0].sellIn);
+        assertEquals(1, app.items[0].quality);
+    }
+
+    @Test
+    void qualityOfAnItemIsNeverNegative() {
+        //given
+        Item testItem = new Item("standard item", 0, 0);
+        Item[] items = new Item[] {testItem};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(-1, app.items[0].sellIn);
+        assertEquals(0, app.items[0].quality);
+    }
+
+    @Test
+    void qualityOfAnItemIsNeverMoreThan50() {
+        //given
+        Item testItem = new Item("standard item", 5, 50);
+        Item[] items = new Item[] {testItem};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(4, app.items[0].sellIn);
+        assertEquals(50, app.items[0].quality);
+    }
+
+    @Test
+    void standardItemQualityDecreasesByOne() {
+        //given
+        Item testItem = new Item("standard item", 5, 2);
+        Item[] items = new Item[] {testItem};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(4, app.items[0].sellIn);
+        assertEquals(1, app.items[0].quality);
     }
 
 }
diff --git a/Java/src/test/java/com/gildedrose/SulfurasTest.java b/Java/src/test/java/com/gildedrose/SulfurasTest.java
new file mode 100644
index 00000000..4aa242bf
--- /dev/null
+++ b/Java/src/test/java/com/gildedrose/SulfurasTest.java
@@ -0,0 +1,38 @@
+package com.gildedrose;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+class SulfurasTest {
+
+    @Test
+    void sulfurasNeverChanges() {
+        //given
+        Item sulfuras = new Item("Sulfuras, Hand of Ragnaros", 0, 80);
+        Item[] items = new Item[] {sulfuras};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(0, app.items[0].sellIn);
+        assertEquals(80, app.items[0].quality);
+    }
+
+    @Test
+    void sulfurasQualityLevelIsAlways80() {
+        //given
+        Item sulfuras = new Item("Sulfuras, Hand of Ragnaros", 0, 80);
+        Item[] items = new Item[] {sulfuras};
+
+        //when
+        GildedRose app = new GildedRose(items);
+        app.updateQuality();
+
+        //then
+        assertEquals(80, app.items[0].quality);
+    }
+
+}