사용 가능한 닉네임 확인 API 구현 및 테스트

boot/api/src/main/java/com/clip/api/docs/user/UserAccountDocs.java

@@ -124,6 +124,26 @@ void updateName(@RequestBody UpdateNameDto updateNameDto,
     void updateNickname(@RequestBody UpdateNicknameDto updateNicknameDto,
                                         @AuthenticationPrincipal UserDetails userDetails);
 
+    @Operation(
+            summary = "사용 가능한 닉네임 확인 API",
+            description = """
+                    해당 닉네임이 사용 가능한지 확인합니다.
+                    다른 유저가 사용중인 닉네임일 경우 HTTP 400 Bad Request를 반환합니다.
+                    """
+    )
+    @ApiResponses(value = {
+            @ApiResponse(
+                    responseCode = "200",
+                    description = "사용 가능한 닉네임"
+            ),
+            @ApiResponse(
+                    responseCode = "400",
+                    description = "사용 불가능한 닉네임"
+            )
+    })
+    @PostMapping("/nickname/available")
+    void checkNicknameAvailable(@RequestBody UpdateNicknameDto updateNicknameDto);
+
     @Operation(
             summary = "유저 상세 정보 업데이트 API",
             description = """

boot/api/src/main/java/com/clip/api/user/controller/UserAccountController.java

@@ -42,6 +42,11 @@ public void updateNickname(UpdateNicknameDto updateNicknameDto,
         userAccountService.updateNickname(Long.parseLong(userDetails.getUsername()), updateNicknameDto.getNickname());
     }
 
+    @Override
+    public void checkNicknameAvailable(UpdateNicknameDto updateNicknameDto) {
+        userAccountService.checkNicknameAvailable(updateNicknameDto.getNickname());
+    }
+
     @Override
     public void updateUserDetailInfo(UpdateUserDetailInfoDto updateUserDetailInfoDto, UserDetails userDetails) {
         userAccountService.updateUserDetailInfo(Long.parseLong(userDetails.getUsername()), updateUserDetailInfoDto);

boot/api/src/main/java/com/clip/api/user/service/UserAccountService.java

@@ -2,7 +2,6 @@
 
 import com.clip.api.user.controller.dto.LoginDto;
 import com.clip.api.user.controller.dto.SignupDto;
-import com.clip.api.user.controller.dto.UpdateNicknameDto;
 import com.clip.api.user.controller.dto.UpdateUserDetailInfoDto;
 import com.clip.api.user.controller.dto.UserInfoDto;
 import com.clip.api.user.exception.NotFoundUserException;
@@ -11,6 +10,7 @@
 import com.clip.auth.service.TokenService;
 import com.clip.global.config.jwt.TokenProvider;
 import com.clip.user.entity.User;
+import com.clip.user.exception.NicknameAlreadyExistsException;
 import com.clip.user.service.TermsAcceptanceService;
 import com.clip.user.service.UserService;
 import lombok.RequiredArgsConstructor;
@@ -92,4 +92,10 @@ public UserInfoDto getUserInfo(String phoneNumber) {
                 .platform(user.getPlatform())
                 .build();
     }
+
+    public void checkNicknameAvailable(String nickname) {
+        if (userService.isExistNickname(nickname)) {
+            throw new NicknameAlreadyExistsException();
+        }
+    }
 }

boot/api/src/test/java/boot/api/com/clip/api/user/service/UserAccountServiceTest.java

@@ -322,4 +322,16 @@ void updateUserDetailInfo() {
                 gender
         );
     }
+
+    @DisplayName("사용중인 닉네임이면 NicknameAlreadyExistsException이 발생한다.")
+    @Test
+    void checkNicknameAvailable() {
+        //given
+        String nickname = "닉네임";
+        userService.save(User.builder().nickname(nickname).build());
+
+        //when & then
+        assertThatThrownBy(() -> userAccountService.checkNicknameAvailable(nickname))
+                .isInstanceOf(NicknameAlreadyExistsException.class);
+    }
 }

boot/api/src/test/java/data/coredata/com/clip/user/entity/repository/UserRepositoryTest.java

@@ -164,4 +164,18 @@ void findUser() {
         //then
         assertThat(foundUser).isEqualTo(user);
     }
+
+    @DisplayName("nickname이 존재하는지 확인한다.")
+    @Test
+    void existsByNickname() {
+        //given
+        String nickname = "닉네임";
+        userRepository.save(User.builder().nickname(nickname).build());
+
+        //when
+        boolean exists = userRepository.existsByNickname(nickname);
+
+        //then
+        assertThat(exists).isTrue();
+    }
 }

data/core-data/src/main/java/com/clip/user/repository/UserRepository.java

@@ -59,4 +59,6 @@ void updateUserDetailInfo(
 
     @Query("select u from User u where u.phoneNumber = :phoneNumber")
     Optional<User> findUser(@Param("phoneNumber") String phoneNumber);
+
+    boolean existsByNickname(String nickname);
 }

data/core-data/src/main/java/com/clip/user/service/UserService.java

@@ -57,4 +57,8 @@ public User findUser(String phoneNumber) {
         return userRepository.findUser(phoneNumber)
                 .orElseThrow(UserNotFoundException::new);
     }
+
+    public boolean isExistNickname(String nickname) {
+        return userRepository.existsByNickname(nickname);
+    }
 }