feat: 발주처 상세 조회 기능 추가

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

@@ -30,6 +30,7 @@ public enum SuccessMessage {
     // VENDOR
     CREATE_VENDOR_SUCCESS("발주처 등록 성공"),
     UPDATE_VENDOR_SUCCESS("발주처 수정 성공"),
+    GET_VENDOR_DETAIL_SUCCESS("발주처 상세 조회 성공"),
     ;
 
     private final String message;

src/main/java/com/almang/inventory/vendor/controller/VendorController.java

@@ -14,6 +14,7 @@
 import lombok.extern.slf4j.Slf4j;
 import org.springframework.http.ResponseEntity;
 import org.springframework.security.core.annotation.AuthenticationPrincipal;
+import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.PatchMapping;
 import org.springframework.web.bind.annotation.PathVariable;
 import org.springframework.web.bind.annotation.PostMapping;
@@ -60,4 +61,19 @@ public ResponseEntity<ApiResponse<VendorResponse>> updateVendor(
                 ApiResponse.success(SuccessMessage.UPDATE_VENDOR_SUCCESS.getMessage(), response)
         );
     }
+
+    @GetMapping("/{vendorId}")
+    @Operation(summary = "발주처 상세 조회", description = "발주처 정보를 반환합니다.")
+    public ResponseEntity<ApiResponse<VendorResponse>> getVendorDetail(
+            @PathVariable Long vendorId,
+            @AuthenticationPrincipal CustomUserPrincipal userPrincipal
+    ) {
+        Long userId = userPrincipal.getId();
+        log.info("[VendorController] 발주처 상세 조회 요청 - vendorId: {}, userId: {}", vendorId, userId);
+        VendorResponse response = vendorService.getVendorDetail(vendorId, userId);
+
+        return ResponseEntity.ok(
+                ApiResponse.success(SuccessMessage.GET_VENDOR_DETAIL_SUCCESS.getMessage(), response)
+        );
+    }
 }

src/main/java/com/almang/inventory/vendor/service/VendorService.java

@@ -48,6 +48,15 @@ public VendorResponse updateVendor(Long vendorId, UpdateVendorRequest request, L
         return VendorResponse.from(vendor);
     }
 
+    @Transactional(readOnly = true)
+    public VendorResponse getVendorDetail(Long vendorId, Long userId) {
+        User user = findUserById(userId);
+        Vendor vendor = findVendorByIdAndValidateAccess(vendorId, user);
+
+        log.info("[VendorService] 발주처 상세 조회 성공 - vendorId: {}", vendor.getId());
+        return VendorResponse.from(vendor);
+    }
+
     private Vendor toEntity(CreateVendorRequest request, User user) {
         return Vendor.builder()
                 .store(user.getStore())

src/test/java/com/almang/inventory/vendor/controller/VendorControllerTest.java

@@ -6,6 +6,7 @@
 import static org.springframework.security.test.web.servlet.request.SecurityMockMvcRequestPostProcessors.authentication;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.patch;
 import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.get;
 import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.*;
 
 import com.almang.inventory.global.api.SuccessMessage;
@@ -234,4 +235,58 @@ private UsernamePasswordAuthenticationToken auth() {
                         .value(ErrorCode.INVALID_INPUT_VALUE.getMessage()))
                 .andExpect(jsonPath("$.data").doesNotExist());
     }
+
+    @Test
+    void 발주처_상세_조회에_성공한다() throws Exception {
+        // given
+        Long vendorId = 1L;
+
+        VendorResponse response = new VendorResponse(
+                vendorId,
+                "테스트 발주처",
+                VendorChannel.KAKAO,
+                "010-1111-2222",
+                "메모",
+                true,
+                1L
+        );
+
+        when(vendorService.getVendorDetail(anyLong(), anyLong()))
+                .thenReturn(response);
+
+        // when & then
+        mockMvc.perform(get("/api/v1/vendor/{vendorId}", vendorId)
+                        .with(authentication(auth()))
+                        .contentType(MediaType.APPLICATION_JSON))
+                .andExpect(status().isOk())
+                .andExpect(jsonPath("$.status").value(200))
+                .andExpect(jsonPath("$.message")
+                        .value(SuccessMessage.GET_VENDOR_DETAIL_SUCCESS.getMessage()))
+                .andExpect(jsonPath("$.data.vendorId").value(vendorId))
+                .andExpect(jsonPath("$.data.name").value("테스트 발주처"))
+                .andExpect(jsonPath("$.data.channel").value("KAKAO"))
+                .andExpect(jsonPath("$.data.contactPoint").value("010-1111-2222"))
+                .andExpect(jsonPath("$.data.note").value("메모"))
+                .andExpect(jsonPath("$.data.storeId").value(1L))
+                .andExpect(jsonPath("$.data.activated").value(true));
+    }
+
+    @Test
+    void 발주처_상세_조회_시_존재하지_않는_발주처면_예외가_발생한다() throws Exception {
+        // given
+        Long vendorId = 9999L;
+
+        when(vendorService.getVendorDetail(anyLong(), anyLong()))
+                .thenThrow(new BaseException(ErrorCode.VENDOR_NOT_FOUND));
+
+        // when & then
+        mockMvc.perform(get("/api/v1/vendor/{vendorId}", vendorId)
+                        .with(authentication(auth()))
+                        .contentType(MediaType.APPLICATION_JSON))
+                .andExpect(status().isNotFound())
+                .andExpect(jsonPath("$.status")
+                        .value(ErrorCode.VENDOR_NOT_FOUND.getHttpStatus().value()))
+                .andExpect(jsonPath("$.message").value(ErrorCode.VENDOR_NOT_FOUND.getMessage()))
+                .andExpect(jsonPath("$.data").doesNotExist());
+    }
 }

src/test/java/com/almang/inventory/vendor/service/VendorServiceTest.java

@@ -238,4 +238,73 @@ private Vendor newVendor(Store store) {
                 .isInstanceOf(BaseException.class)
                 .hasMessageContaining(ErrorCode.VENDOR_ACCESS_DENIED.getMessage());
     }
+
+    @Test
+    void 발주처_상세_조회에_성공한다() {
+        // given
+        Store store = newStore();
+        User user = newUser(store);
+        Vendor vendor = newVendor(store);
+
+        // when
+        VendorResponse response = vendorService.getVendorDetail(vendor.getId(), user.getId());
+
+        // then
+        assertThat(response.vendorId()).isEqualTo(vendor.getId());
+        assertThat(response.name()).isEqualTo("기존 발주처");
+        assertThat(response.channel()).isEqualTo(VendorChannel.KAKAO);
+        assertThat(response.contactPoint()).isEqualTo("010-1111-1111");
+        assertThat(response.note()).isEqualTo("원본 메모");
+        assertThat(response.storeId()).isEqualTo(store.getId());
+        assertThat(response.activated()).isTrue();
+    }
+
+    @Test
+    void 존재하지_않는_발주처_상세_조회시_예외가_발생한다() {
+        // given
+        Store store = newStore();
+        User user = newUser(store);
+        Long notExistVendorId = 9999L;
+
+        // when & then
+        assertThatThrownBy(() -> vendorService.getVendorDetail(notExistVendorId, user.getId()))
+                .isInstanceOf(BaseException.class)
+                .hasMessageContaining(ErrorCode.VENDOR_NOT_FOUND.getMessage());
+    }
+
+    @Test
+    void 다른_상점_발주처_상세_조회시_예외가_발생한다() {
+        // given
+        Store store1 = newStore();
+        Store store2 = newStore();
+
+        User userOfStore1 = newUser(store1);
+        User userOfStore2 = userRepository.save(
+                User.builder()
+                        .store(store2)
+                        .username("detail_tester_store2")
+                        .password("password")
+                        .name("상점2 관리자")
+                        .role(UserRole.ADMIN)
+                        .build()
+        );
+
+        Vendor vendorOfStore2 = vendorRepository.save(
+                Vendor.builder()
+                        .store(store2)
+                        .name("상점2 발주처")
+                        .channel(VendorChannel.KAKAO)
+                        .contactPoint("010-2222-2222")
+                        .note("상점2 메모")
+                        .activated(true)
+                        .build()
+        );
+
+        // when & then
+        assertThatThrownBy(() ->
+                vendorService.getVendorDetail(vendorOfStore2.getId(), userOfStore1.getId())
+        )
+                .isInstanceOf(BaseException.class)
+                .hasMessageContaining(ErrorCode.VENDOR_ACCESS_DENIED.getMessage());
+    }
 }