increasing test coverage

Java/src/test/java/com/gildedrose/core/rule/InventoryRuleEngineTest.java

@@ -9,7 +9,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 public class InventoryRuleEngineTest {
 
     @Test
-    void shouldProcessAgedBrieRule() {
+    void shouldApplyAgedBrieRule() {
         //given
         ItemAdapter itemAdapter = new ItemAdapter(ItemType.AGEG_BRIE, new Item("Aged Brie", 3, 0));
 
@@ -20,4 +20,46 @@ public class InventoryRuleEngineTest {
         assertEquals(2, itemAdapter.getItem().sellIn);
         assertEquals(1, itemAdapter.getItem().quality);
     }
+
+    @Test
+    void shouldApplySulfurasRule() {
+        //given
+        ItemAdapter itemAdapter = new ItemAdapter(ItemType.SULFURAS,
+            new Item("Sulfuras, Hand of Ragnaros", 3, 80));
+
+        //when
+        InventoryRuleEngine.applyUpdateRule(itemAdapter);
+
+        //then
+        assertEquals(3, itemAdapter.getItem().sellIn);
+        assertEquals(80, itemAdapter.getItem().quality);
+    }
+
+    @Test
+    void shouldApplyBackstagePassesRule() {
+        //given
+        ItemAdapter itemAdapter = new ItemAdapter(ItemType.BACKSTAGE_PASSES,
+            new Item("Backstage passes to a TAFKAL80ETC concert", 3, 10));
+
+        //when
+        InventoryRuleEngine.applyUpdateRule(itemAdapter);
+
+        //then
+        assertEquals(2, itemAdapter.getItem().sellIn);
+        assertEquals(13, itemAdapter.getItem().quality);
+    }
+
+    @Test
+    void shouldApplyStandardItemRule() {
+        //given
+        ItemAdapter itemAdapter = new ItemAdapter(ItemType.STANDARD,
+            new Item("Elixir of the Mongoose", 5, 7));
+
+        //when
+        InventoryRuleEngine.applyUpdateRule(itemAdapter);
+
+        //then
+        assertEquals(4, itemAdapter.getItem().sellIn);
+        assertEquals(6, itemAdapter.getItem().quality);
+    }
 }