@@ -0,0 +1,101 @@
+package store.domain;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import camp.nextstep.edu.missionutils.DateTimes;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.CsvSource;
+
+public class CartItemTest {
+    private Product product;
+    private Promotion promotion;
+    private CartItem cartItem;
+
+    @BeforeEach
+    void setup() {
+        promotion = new Promotion("Buy 2 Get 1 Free", 2, 1, DateTimes.now().toLocalDate().minusDays(1),
+                DateTimes.now().toLocalDate().plusDays(1));
+        product = new Product("Sample Product", 1000, 10, promotion);
+        cartItem = new CartItem(product, 5);
+    }
+
+    @Test
+    void 총가격_계산_성공() {
+        Money totalPrice = cartItem.calculateTotalPrice();
+        assertThat(totalPrice.getAmount()).isEqualTo(5000);
+    }
+
+    @ParameterizedTest
+    @CsvSource({"5, 1000", "7, 2000", "15, 3000"})
+    void 프로모션할인_계산_성공(int quantity, int expectedDiscount) {
+        CartItem cartItem = new CartItem(product, quantity);
+        int discount = cartItem.calculatePromotionDiscount();
+        assertThat(discount).isEqualTo(expectedDiscount);
+    }
+
+    @Test
+    void 프로모션할인_없는경우_계산_성공() {
+        Product noPromoProduct = new Product("No Promo Product", 1000, 10, null);
+        CartItem cartItem = new CartItem(noPromoProduct, 5);
+        int discount = cartItem.calculatePromotionDiscount();
+        assertThat(discount).isEqualTo(0);
+    }
+
+    @Test
+    void 유효하지않은_프로모션_적용_예외() {
+        Promotion expiredPromotion = new Promotion("Expired Promo", 2, 1, DateTimes.now().toLocalDate().minusDays(10),
+                DateTimes.now().toLocalDate().minusDays(1));
+        Product expiredProduct = new Product("Expired Product", 1000, 10, expiredPromotion);
+        CartItem cartItem = new CartItem(expiredProduct, 5);
+
+        boolean isValid = cartItem.isPromotionValid();
+        assertThat(isValid).isFalse();
+    }
+
+    @Test
+    void 프로모션_재고부족_예외() {
+        Product lowStockProduct = new Product("Low Stock Product", 1000, 1, promotion);
+        CartItem cartItem = new CartItem(lowStockProduct, 6);
+
+        boolean stockAvailable = cartItem.checkPromotionStock();
+        assertThat(stockAvailable).isTrue();
+    }
+
+    @Test
+    void 유효한_프로모션_재고_확인() {
+        boolean stockAvailable = cartItem.checkPromotionStock();
+        assertThat(stockAvailable).isFalse();
+    }
+
+    @Test
+    void 무료수량_계산_성공() {
+        int freeQuantity = cartItem.getFreeQuantity();
+        assertThat(freeQuantity).isEqualTo(1);
+    }
+
+    @Test
+    void 남은수량_계산_성공() {
+        int remainingQuantity = cartItem.calculateRemainingQuantity();
+        assertThat(remainingQuantity).isEqualTo(0);
+    }
+
+    @Test
+    void 추가_필요한_수량_계산_성공() {
+        int additionalQuantity = cartItem.calculateAdditionalQuantityNeeded();
+        assertThat(additionalQuantity).isEqualTo(1);
+    }
+
+    @Test
+    void 수량_업데이트_후_아이템_생성_성공() {
+        CartItem updatedItem = cartItem.withUpdatedQuantityForFullPrice(10);
+        assertThat(updatedItem.getQuantity()).isEqualTo(10);
+    }
+
+    @Test
+    void 추가_수량_적용_후_아이템_생성_성공() {
+        CartItem updatedItem = cartItem.withAdditionalQuantity(3);
+        assertThat(updatedItem.getQuantity()).isEqualTo(8);
+    }
+}

리뷰: 테스트코드를 굉장히 꼼꼼하게 구현하셨네요 좋은 것 같아요👍