Add increasing quality behavior and test

Java/src/main/java/com/gildedrose/behavior/quality/IncreasingQualityBehavior.java

@@ -0,0 +1,22 @@
+package com.gildedrose.behavior.quality;
+
+import com.gildedrose.Item;
+
+public class IncreasingQualityBehavior implements QualityBehavior {
+
+    public static final int MAX_QUALITY_LEVEL = 50;
+    public static final int MIN_QUALITY_LEVEL = 0;
+
+    @Override
+    public void processQualityUpdate(Item item) {
+        increaseQuality(item);
+    }
+
+    private void increaseQuality(Item item) {
+        item.quality = limitQuality(item.quality + 1);
+    }
+
+    private int limitQuality(int newQuality) {
+        return Math.max(MIN_QUALITY_LEVEL, Math.min(MAX_QUALITY_LEVEL, newQuality));
+    }
+}

Java/src/test/java/com/gildedrose/behavior/quality/IncreasingQualityBehaviorTest.java

@@ -0,0 +1,45 @@
+package com.gildedrose.behavior.quality;
+
+import com.gildedrose.Item;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class IncreasingQualityBehaviorTest {
+
+    private QualityBehavior qualityBehavior;
+
+    @BeforeEach
+    public void setUp() throws Exception {
+        qualityBehavior = new IncreasingQualityBehavior();
+    }
+
+    @Test
+    void increaseQuality() {
+        Item item = getItem(10);
+        qualityBehavior.processQualityUpdate(item);
+
+        assertEquals(11, item.quality);
+    }
+
+    @Test
+    void increaseAboveTreshold() {
+        Item item = getItem(99);
+        qualityBehavior.processQualityUpdate(item);
+
+        assertEquals(50, item.quality);
+    }
+
+    @Test
+    void increaseQualityAtTreshold() {
+        Item item = getItem(50);
+        qualityBehavior.processQualityUpdate(item);
+
+        assertEquals(50, item.quality);
+    }
+
+    private Item getItem(int quality) {
+        return new Item("SomeItem", 0, quality);
+    }
+}