feat: 발주 아이템 조회 기능 구현

src/main/java/com/almang/inventory/global/api/SuccessMessage.java

@@ -43,6 +43,7 @@ public enum SuccessMessage {
     GET_ORDER_SUCCESS("발주 조회 성공"),
     GET_ORDER_LIST_SUCCESS("발주 목록 조회 성공"),
     UPDATE_ORDER_SUCCESS("발주 수정 성공"),
+    GET_ORDER_ITEM_SUCCESS("발주 아이템 조회 성공"),
     ;
 
     private final String message;

src/main/java/com/almang/inventory/order/controller/OrderController.java

@@ -7,6 +7,7 @@
 import com.almang.inventory.order.domain.OrderStatus;
 import com.almang.inventory.order.dto.request.CreateOrderRequest;
 import com.almang.inventory.order.dto.request.UpdateOrderRequest;
+import com.almang.inventory.order.dto.response.OrderItemResponse;
 import com.almang.inventory.order.dto.response.OrderResponse;
 import com.almang.inventory.order.service.OrderService;
 import io.swagger.v3.oas.annotations.Operation;
@@ -102,4 +103,19 @@ public ResponseEntity<ApiResponse<OrderResponse>> updateOrder(
                 ApiResponse.success(SuccessMessage.UPDATE_ORDER_SUCCESS.getMessage(), response)
         );
     }
+
+    @GetMapping("/item/{orderItemId}")
+    @Operation(summary = "발주 아이템 조회", description = "발주 아이템 조회합니다.")
+    public ResponseEntity<ApiResponse<OrderItemResponse>> getOrderItem(
+            @PathVariable Long orderItemId,
+            @AuthenticationPrincipal CustomUserPrincipal userPrincipal
+    ) {
+        Long userId = userPrincipal.getId();
+        log.info("[OrderController] 발주 아이템 조회 요청 - orderItemId: {}, userId: {}", orderItemId, userId);
+        OrderItemResponse response = orderService.getOrderItem(orderItemId, userId);
+
+        return ResponseEntity.ok(
+                ApiResponse.success(SuccessMessage.GET_ORDER_ITEM_SUCCESS.getMessage(), response)
+        );
+    }
 }

src/main/java/com/almang/inventory/order/dto/response/OrderItemResponse.java

@@ -10,7 +10,8 @@ public record OrderItemResponse(
         Long productId,
         Integer quantity,
         Integer unitPrice,
-        Integer amount
+        Integer amount,
+        String note
 ) {
     public static OrderItemResponse from(OrderItem orderItem) {
         if (orderItem.getOrder() == null || orderItem.getProduct() == null) {
@@ -22,7 +23,8 @@ public static OrderItemResponse from(OrderItem orderItem) {
                 orderItem.getProduct().getId(),
                 orderItem.getQuantity(),
                 orderItem.getUnitPrice(),
-                orderItem.getAmount()
+                orderItem.getAmount(),
+                orderItem.getNote()
         );
     }
 }

src/main/java/com/almang/inventory/order/service/OrderService.java

@@ -11,6 +11,7 @@
 import com.almang.inventory.order.dto.request.CreateOrderRequest;
 import com.almang.inventory.order.dto.request.UpdateOrderItemRequest;
 import com.almang.inventory.order.dto.request.UpdateOrderRequest;
+import com.almang.inventory.order.dto.response.OrderItemResponse;
 import com.almang.inventory.order.dto.response.OrderResponse;
 import com.almang.inventory.order.repository.OrderItemRepository;
 import com.almang.inventory.order.repository.OrderRepository;
@@ -115,6 +116,19 @@ public OrderResponse updateOrder(Long orderId, UpdateOrderRequest request, Long
         return OrderResponse.of(order, order.getItems());
     }
 
+    @Transactional(readOnly = true)
+    public OrderItemResponse getOrderItem(Long orderItemId, Long userId) {
+        User user = findUserById(userId);
+        Store store = user.getStore();
+
+        log.info("[OrderService] 발주 상세 조회 요청 - userId: {}, storeId: {}", userId, store.getId());
+        OrderItem orderItem = findOrderItemById(orderItemId);
+        validateOrderItemAccess(orderItem, store);
+
+        log.info("[OrderService] 발주 상세 조회 성공 - orderItemId: {}", orderItem.getId());
+        return OrderItemResponse.from(orderItem);
+    }
+
     private List<OrderItem> createOrderItems(List<CreateOrderItemRequest> requests, Store store) {
         List<OrderItem> items = new ArrayList<>();
 
@@ -270,4 +284,15 @@ private void updateOrderItems(Order order, UpdateOrderRequest request) {
         }
         order.updateTotalPrice(calculateTotalPrice(order.getItems()));
     }
+
+    private OrderItem findOrderItemById(Long orderItemId) {
+        return orderItemRepository.findById(orderItemId)
+                .orElseThrow(() -> new BaseException(ErrorCode.ORDER_ITEM_NOT_FOUND));
+    }
+
+    private void validateOrderItemAccess(OrderItem orderItem, Store store) {
+        if (!orderItem.getOrder().getStore().getId().equals(store.getId())) {
+            throw new BaseException(ErrorCode.ORDER_ITEM_ACCESS_DENIED);
+        }
+    }
 }

src/test/java/com/almang/inventory/order/controller/OrderControllerTest.java

@@ -20,6 +20,7 @@
 import com.almang.inventory.order.dto.request.CreateOrderRequest;
 import com.almang.inventory.order.dto.request.UpdateOrderItemRequest;
 import com.almang.inventory.order.dto.request.UpdateOrderRequest;
+import com.almang.inventory.order.dto.response.OrderItemResponse;
 import com.almang.inventory.order.dto.response.OrderResponse;
 import com.almang.inventory.order.service.OrderService;
 
@@ -563,4 +564,72 @@ private UsernamePasswordAuthenticationToken auth() {
                         .value(ErrorCode.VENDOR_CHANGE_NOT_ALLOWED.getMessage()))
                 .andExpect(jsonPath("$.data").doesNotExist());
     }
+
+    @Test
+    void 발주_아이템_조회에_성공한다() throws Exception {
+        // given
+        Long orderItemId = 1L;
+
+        OrderItemResponse response = new OrderItemResponse(
+                orderItemId,
+                100L,
+                10L,
+                5,
+                1000,
+                5000,
+                "비고입니다"
+        );
+
+        when(orderService.getOrderItem(anyLong(), anyLong()))
+                .thenReturn(response);
+
+        // when & then
+        mockMvc.perform(get("/api/v1/order/item/{orderItemId}", orderItemId)
+                        .with(authentication(auth())))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.status").value(200))
+                .andExpect(jsonPath("$.message")
+                        .value(SuccessMessage.GET_ORDER_ITEM_SUCCESS.getMessage()))
+                .andExpect(jsonPath("$.data.orderItemId").value(orderItemId))
+                .andExpect(jsonPath("$.data.orderId").value(100L))
+                .andExpect(jsonPath("$.data.productId").value(10L));
+    }
+
+    @Test
+    void 발주_아이템_조회시_존재하지_않으면_예외가_발생한다() throws Exception {
+        // given
+        Long notExistOrderItemId = 9999L;
+
+        when(orderService.getOrderItem(anyLong(), anyLong()))
+                .thenThrow(new BaseException(ErrorCode.ORDER_ITEM_NOT_FOUND));
+
+        // when & then
+        mockMvc.perform(get("/api/v1/order/item/{orderItemId}", notExistOrderItemId)
+                        .with(authentication(auth())))
+                .andExpect(status().isNotFound())
+                .andExpect(jsonPath("$.status")
+                        .value(ErrorCode.ORDER_ITEM_NOT_FOUND.getHttpStatus().value()))
+                .andExpect(jsonPath("$.message")
+                        .value(ErrorCode.ORDER_ITEM_NOT_FOUND.getMessage()))
+                .andExpect(jsonPath("$.data").doesNotExist());
+    }
+
+    @Test
+    void 발주_아이템_조회시_다른_상점의_아이템이면_접근_거부_예외가_발생한다() throws Exception {
+        // given
+        Long orderItemId = 1L;
+
+        when(orderService.getOrderItem(anyLong(), anyLong()))
+                .thenThrow(new BaseException(ErrorCode.ORDER_ITEM_ACCESS_DENIED));
+
+        // when & then
+        mockMvc.perform(get("/api/v1/order/item/{orderItemId}", orderItemId)
+                        .with(authentication(auth())))
+                .andExpect(status().isForbidden())
+                .andExpect(jsonPath("$.status")
+                        .value(ErrorCode.ORDER_ITEM_ACCESS_DENIED.getHttpStatus().value()))
+                .andExpect(jsonPath("$.message")
+                        .value(ErrorCode.ORDER_ITEM_ACCESS_DENIED.getMessage()))
+                .andExpect(jsonPath("$.data").doesNotExist());
+    }
 }

src/test/java/com/almang/inventory/order/service/OrderServiceTest.java

@@ -13,6 +13,7 @@
 import com.almang.inventory.order.dto.request.CreateOrderRequest;
 import com.almang.inventory.order.dto.request.UpdateOrderItemRequest;
 import com.almang.inventory.order.dto.request.UpdateOrderRequest;
+import com.almang.inventory.order.dto.response.OrderItemResponse;
 import com.almang.inventory.order.dto.response.OrderResponse;
 import com.almang.inventory.order.repository.OrderRepository;
 import com.almang.inventory.product.domain.Product;
@@ -888,4 +889,86 @@ private Product newProduct(Store store, Vendor vendor, String name, String code)
                 .isInstanceOf(BaseException.class)
                 .hasMessageContaining(ErrorCode.ORDER_ITEM_ACCESS_DENIED.getMessage());
     }
+
+    @Test
+    void 발주_상세_조회에_성공한다() {
+        // given
+        Store store = newStore("테스트 상점");
+        User user = newUser(store, "order_item_reader");
+        Vendor vendor = newVendor(store, "발주처1");
+        Product product = newProduct(store, vendor, "상품1", "P001");
+
+        CreateOrderRequest createRequest = new CreateOrderRequest(
+                vendor.getId(),
+                "발주 메시지",
+                3,
+                List.of(new CreateOrderItemRequest(product.getId(), 2, 1000, "비고"))
+        );
+
+        OrderResponse created = orderService.createOrder(createRequest, user.getId());
+        Long orderId = created.orderId();
+
+        Order order = orderRepository.findById(orderId)
+                .orElseThrow();
+        OrderItem orderItem = order.getItems().get(0);
+        Long orderItemId = orderItem.getId();
+
+        // when
+        OrderItemResponse response = orderService.getOrderItem(orderItemId, user.getId());
+
+        // then
+        assertThat(response).isNotNull();
+        assertThat(response.orderItemId()).isEqualTo(orderItemId);
+        assertThat(response.productId()).isEqualTo(product.getId());
+        assertThat(response.quantity()).isEqualTo(2);
+        assertThat(response.unitPrice()).isEqualTo(1000);
+        assertThat(response.amount()).isEqualTo(2 * 1000);
+        assertThat(response.note()).isEqualTo("비고");
+    }
+
+    @Test
+    void 발주_상세_조회시_발주_항목이_존재하지_않으면_예외가_발생한다() {
+        // given
+        Store store = newStore("테스트 상점");
+        User user = newUser(store, "order_item_reader");
+        Long notExistOrderItemId = 9999L;
+
+        // when & then
+        assertThatThrownBy(() -> orderService.getOrderItem(notExistOrderItemId, user.getId()))
+                .isInstanceOf(BaseException.class)
+                .hasMessageContaining(ErrorCode.ORDER_ITEM_NOT_FOUND.getMessage());
+    }
+
+    @Test
+    void 발주_상세_조회시_다른_상점의_발주_항목이면_접근_거부_예외가_발생한다() {
+        // given
+        Store store1 = newStore("상점1");
+        Store store2 = newStore("상점2");
+
+        User userOfStore1 = newUser(store1, "user1");
+        User userOfStore2 = newUser(store2, "user2");
+
+        Vendor vendorOfStore2 = newVendor(store2, "상점2 발주처");
+        Product productOfStore2 = newProduct(store2, vendorOfStore2, "상점2 상품", "P999");
+
+        OrderResponse created = orderService.createOrder(
+                new CreateOrderRequest(
+                        vendorOfStore2.getId(),
+                        "상점2 발주",
+                        2,
+                        List.of(new CreateOrderItemRequest(productOfStore2.getId(), 3, 1000, "비고"))
+                ),
+                userOfStore2.getId()
+        );
+
+        Long orderId = created.orderId();
+        Order order2 = orderRepository.findById(orderId)
+                .orElseThrow();
+        Long orderItemId = order2.getItems().get(0).getId();
+
+        // when & then
+        assertThatThrownBy(() -> orderService.getOrderItem(orderItemId, userOfStore1.getId()))
+                .isInstanceOf(BaseException.class)
+                .hasMessageContaining(ErrorCode.ORDER_ITEM_ACCESS_DENIED.getMessage());
+    }
 }