feat: 아이템 목록 조회 Response에 현재 적용된 아이템 속성 추가

src/main/java/com/moabam/api/application/item/ItemMapper.java

@@ -27,8 +27,9 @@ public static ItemResponse toItemResponse(Item item) {
 			.build();
 	}
 
-	public static ItemsResponse toItemsResponse(List<Item> purchasedItems, List<Item> notPurchasedItems) {
+	public static ItemsResponse toItemsResponse(Long itemId, List<Item> purchasedItems, List<Item> notPurchasedItems) {
 		return ItemsResponse.builder()
+			.defaultItemId(itemId)
 			.purchasedItems(StreamUtils.map(purchasedItems, ItemMapper::toItemResponse))
 			.notPurchasedItems(StreamUtils.map(notPurchasedItems, ItemMapper::toItemResponse))
 			.build();

src/main/java/com/moabam/api/application/item/ItemService.java

@@ -39,10 +39,11 @@ public class ItemService {
 	private final BugHistoryRepository bugHistoryRepository;
 
 	public ItemsResponse getItems(Long memberId, ItemType type) {
+		Item defaultItem = getDefaultInventory(memberId, type).getItem();
 		List<Item> purchasedItems = inventorySearchRepository.findItems(memberId, type);
 		List<Item> notPurchasedItems = itemSearchRepository.findNotPurchasedItems(memberId, type);
 
-		return ItemMapper.toItemsResponse(purchasedItems, notPurchasedItems);
+		return ItemMapper.toItemsResponse(defaultItem.getId(), purchasedItems, notPurchasedItems);
 	}
 
 	@Transactional
@@ -80,6 +81,11 @@ private Inventory getInventory(Long memberId, Long itemId) {
 			.orElseThrow(() -> new NotFoundException(INVENTORY_NOT_FOUND));
 	}
 
+	private Inventory getDefaultInventory(Long memberId, ItemType type) {
+		return inventorySearchRepository.findDefault(memberId, type)
+			.orElseThrow(() -> new NotFoundException(DEFAULT_INVENTORY_NOT_FOUND));
+	}
+
 	private void validateAlreadyPurchased(Long memberId, Long itemId) {
 		inventorySearchRepository.findOne(memberId, itemId)
 			.ifPresent(inventory -> {

src/main/java/com/moabam/api/dto/item/ItemsResponse.java

@@ -6,6 +6,7 @@
 
 @Builder
 public record ItemsResponse(
+	Long defaultItemId,
 	List<ItemResponse> purchasedItems,
 	List<ItemResponse> notPurchasedItems
 ) {

src/main/java/com/moabam/global/error/model/ErrorMessage.java

@@ -40,6 +40,7 @@ public enum ErrorMessage {
 	ITEM_UNLOCK_LEVEL_HIGH("아이템 해금 레벨이 높습니다."),
 	ITEM_NOT_PURCHASABLE_BY_BUG_TYPE("해당 벌레 타입으로는 구매할 수 없는 아이템입니다."),
 	INVENTORY_NOT_FOUND("구매하지 않은 아이템은 적용할 수 없습니다."),
+	DEFAULT_INVENTORY_NOT_FOUND("현재 적용된 아이템이 없습니다."),
 	INVENTORY_CONFLICT("이미 구매한 아이템입니다."),
 
 	INVALID_BUG_COUNT("벌레 개수는 0 이상이어야 합니다."),

src/test/java/com/moabam/api/application/item/ItemServiceTest.java

@@ -70,6 +70,8 @@ void get_products_success() {
 		ItemType type = ItemType.MORNING;
 		Item item1 = morningSantaSkin().build();
 		Item item2 = morningKillerSkin().build();
+		Inventory inventory = inventory(memberId, item1);
+		given(inventorySearchRepository.findDefault(memberId, type)).willReturn(Optional.of(inventory));
 		given(inventorySearchRepository.findItems(memberId, type)).willReturn(List.of(item1, item2));
 		given(itemSearchRepository.findNotPurchasedItems(memberId, type)).willReturn(emptyList());
 

src/test/java/com/moabam/api/presentation/ItemControllerTest.java

@@ -30,6 +30,7 @@
 import com.moabam.api.application.item.ItemMapper;
 import com.moabam.api.application.member.MemberService;
 import com.moabam.api.domain.bug.BugType;
+import com.moabam.api.domain.item.Inventory;
 import com.moabam.api.domain.item.Item;
 import com.moabam.api.domain.item.ItemType;
 import com.moabam.api.domain.item.repository.InventoryRepository;
@@ -70,9 +71,10 @@ void success() throws Exception {
 			// given
 			Long memberId = getAuthorizationMember().id();
 			Item item1 = itemRepository.save(morningSantaSkin().build());
-			inventoryRepository.save(inventory(memberId, item1));
+			Inventory inventory = inventoryRepository.save(inventory(memberId, item1));
+			inventory.select();
 			Item item2 = itemRepository.save(morningKillerSkin().build());
-			ItemsResponse expected = ItemMapper.toItemsResponse(List.of(item1), List.of(item2));
+			ItemsResponse expected = ItemMapper.toItemsResponse(item1.getId(), List.of(item1), List.of(item2));
 
 			// expected
 			String content = mockMvc.perform(get("/items")