✅ normal item unit test

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

@@ -0,0 +1,50 @@
+package com.gildedrose;
+
+import com.gildedrose.main.GildedRose;
+import com.gildedrose.main.Item;
+import org.junit.jupiter.api.Test;
+
+import static com.gildedrose.item_helpers.ItemName.NORMAL;
+import static org.junit.jupiter.api.Assertions.*;
+
+class NormalItemTest {
+
+    @Test
+    void decrementQualityByOneSuccess() {
+        // given
+        Item normalItem = new Item(NORMAL.toString(), 5, 20);
+        GildedRose app = new GildedRose(normalItem);
+        // when
+        int days = 2;
+        for (int i = 0; i < days; i++) {
+            app.updateQuality();
+        }
+        //then
+        assertEquals(18, normalItem.quality);
+        assertEquals(3, normalItem.sellIn);
+    }
+
+    @Test
+    void decrementQualityByTwoSuccess() {
+        // given
+        Item normalItem = new Item(NORMAL.toString(), 10, 20);
+        GildedRose app = new GildedRose(normalItem);
+        // when
+        int days = 15;
+        for (int i = 0; i < days; i++) {
+            app.updateQuality();
+        }
+        //then
+        assertEquals(0, normalItem.quality);
+        assertEquals(-5, normalItem.sellIn);
+    }
+
+    @Test
+    void negativeQualityFail() {
+        Item normalItem = new Item(NORMAL.toString(), 10, -5);
+        GildedRose app = new GildedRose(normalItem);
+        Exception exception = assertThrows(IllegalArgumentException.class, app::updateQuality);
+        String actualMessage = exception.getMessage();
+        assertTrue(actualMessage.contains("Quality cannot be negative! Current value:"));
+    }
+}