src/test/java/ItemStackTest.java

@@ -0,0 +1,27 @@
+import Item.BasicItem;
+import Item.ItemStack;
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+
+public class ItemStackTest {
+    @Test
+    void instantiated_with_no_quantity_throws_exception() {
+        assertThrows(IllegalArgumentException.class, () -> new ItemStack(
+                new BasicItem("id", "name", 5), 0
+        ));
+    }
+    @Test
+    void instantiated_with_negative_quantity_throws_exception() {
+        assertThrows(IllegalArgumentException.class, () -> new ItemStack(
+                new BasicItem("id", "name", 5), -4
+        ));
+    }
+
+    @Test
+    void can_be_created_with_positive_quantity() {
+        var i = new ItemStack(new BasicItem("id", "name", 5), 5);
+        assertEquals(5, i.getQuantity());
+    }
+}