feat: 팔로우 추가 / 취소 기능

src/main/java/com/depromeet/domain/follow/api/FollowController.java

@@ -0,0 +1,33 @@
+package com.depromeet.domain.follow.api;
+
+import com.depromeet.domain.follow.application.FollowService;
+import com.depromeet.domain.follow.dto.request.FollowCreateRequest;
+import com.depromeet.domain.follow.dto.request.FollowDeleteRequest;
+import io.swagger.v3.oas.annotations.Operation;
+import io.swagger.v3.oas.annotations.tags.Tag;
+import jakarta.validation.Valid;
+import lombok.RequiredArgsConstructor;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+@Tag(name = "5. [팔로우]", description = "팔로우 관련 API입니다.")
+@RestController
+@RequestMapping("/follows")
+@RequiredArgsConstructor
+public class FollowController {
+    private final FollowService followService;
+
+    @PostMapping
+    @Operation(summary = "팔로우 추가", description = "팔로우를 추가합니다.")
+    public ResponseEntity<Void> followCreate(@Valid @RequestBody FollowCreateRequest request) {
+        followService.createFollow(request);
+        return ResponseEntity.status(HttpStatus.CREATED).build();
+    }
+
+    @DeleteMapping
+    @Operation(summary = "팔로우 취소", description = "팔로우를 취소합니다.")
+    public void followDelete(@Valid @RequestBody FollowDeleteRequest request) {
+        followService.deleteFollow(request);
+    }
+}

src/main/java/com/depromeet/domain/follow/application/FollowService.java

@@ -0,0 +1,62 @@
+package com.depromeet.domain.follow.application;
+
+import com.depromeet.domain.follow.dao.MemberRelationRepository;
+import com.depromeet.domain.follow.domain.MemberRelation;
+import com.depromeet.domain.follow.dto.request.FollowCreateRequest;
+import com.depromeet.domain.follow.dto.request.FollowDeleteRequest;
+import com.depromeet.domain.member.dao.MemberRepository;
+import com.depromeet.domain.member.domain.Member;
+import com.depromeet.global.error.exception.CustomException;
+import com.depromeet.global.error.exception.ErrorCode;
+import com.depromeet.global.util.MemberUtil;
+import lombok.RequiredArgsConstructor;
+import org.springframework.stereotype.Service;
+import org.springframework.transaction.annotation.Transactional;
+
+@Service
+@RequiredArgsConstructor
+@Transactional
+public class FollowService {
+    private final MemberUtil memberUtil;
+    private final MemberRepository memberRepository;
+    private final MemberRelationRepository memberRelationRepository;
+
+    public void createFollow(FollowCreateRequest request) {
+        final Member currentMember = memberUtil.getCurrentMember();
+        Member targetMember = getTargetMember(request.targetId());
+
+        boolean existMemberRelation =
+                memberRelationRepository.existsByFollowerIdAndFollowingId(
+                        currentMember.getId(), targetMember.getId());
+        if (existMemberRelation) {
+            throw new CustomException(ErrorCode.FOLLOW_ALREADY_EXIST);
+        }
+
+        MemberRelation memberRelation =
+                MemberRelation.createMemberRelation(currentMember, targetMember);
+        memberRelationRepository.save(memberRelation);
+    }
+
+    public void deleteFollow(FollowDeleteRequest request) {
+        final Member currentMember = memberUtil.getCurrentMember();
+        Member targetMember = getTargetMember(request.targetId());
+
+        MemberRelation memberRelation =
+                memberRelationRepository
+                        .findByFollowerIdAndFollowingId(currentMember.getId(), targetMember.getId())
+                        .orElseThrow(() -> new CustomException(ErrorCode.FOLLOW_NOT_EXIST));
+
+        memberRelationRepository.delete(memberRelation);
+    }
+
+    private Member getTargetMember(Long targetId) {
+        Member targetMember =
+                memberRepository
+                        .findById(targetId)
+                        .orElseThrow(
+                                () ->
+                                        new CustomException(
+                                                ErrorCode.FOLLOW_TARGET_MEMBER_NOT_FOUND));
+        return targetMember;
+    }
+}

src/main/java/com/depromeet/domain/follow/dao/MemberRelationRepository.java

@@ -0,0 +1,11 @@
+package com.depromeet.domain.follow.dao;
+
+import com.depromeet.domain.follow.domain.MemberRelation;
+import java.util.Optional;
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface MemberRelationRepository extends JpaRepository<MemberRelation, Long> {
+    Optional<MemberRelation> findByFollowerIdAndFollowingId(Long followerId, Long followingId);
+
+    boolean existsByFollowerIdAndFollowingId(Long followerId, Long followingId);
+}

src/main/java/com/depromeet/domain/relation/domain/MemberRelation.java → src/main/java/com/depromeet/domain/follow/domain/MemberRelation.java

@@ -1,4 +1,4 @@
-package com.depromeet.domain.relation.domain;
+package com.depromeet.domain.follow.domain;
 
 import com.depromeet.domain.common.model.BaseTimeEntity;
 import com.depromeet.domain.member.domain.Member;
@@ -12,6 +12,7 @@
 import jakarta.persistence.Table;
 import jakarta.persistence.UniqueConstraint;
 import lombok.AccessLevel;
+import lombok.Builder;
 import lombok.Getter;
 import lombok.NoArgsConstructor;
 
@@ -37,4 +38,15 @@ public class MemberRelation extends BaseTimeEntity {
     @ManyToOne
     @JoinColumn(name = "following_id")
     private Member following;
+
+    @Builder(access = AccessLevel.PRIVATE)
+    private MemberRelation(Long id, Member follower, Member following) {
+        this.id = id;
+        this.follower = follower;
+        this.following = following;
+    }
+
+    public static MemberRelation createMemberRelation(Member follower, Member following) {
+        return MemberRelation.builder().follower(follower).following(following).build();
+    }
 }

src/main/java/com/depromeet/domain/follow/dto/request/FollowCreateRequest.java

@@ -0,0 +1,5 @@
+package com.depromeet.domain.follow.dto.request;
+
+import jakarta.validation.constraints.NotNull;
+
+public record FollowCreateRequest(@NotNull(message = "타겟 아이디는 비워둘 수 없습니다.") Long targetId) {}

src/main/java/com/depromeet/domain/follow/dto/request/FollowDeleteRequest.java

@@ -0,0 +1,5 @@
+package com.depromeet.domain.follow.dto.request;
+
+import jakarta.validation.constraints.NotNull;
+
+public record FollowDeleteRequest(@NotNull(message = "타겟 아이디는 비워둘 수 없습니다.") Long targetId) {}

src/main/java/com/depromeet/global/error/exception/ErrorCode.java

@@ -46,6 +46,11 @@ public enum ErrorCode {
     MISSION_RECORD_UPLOAD_STATUS_IS_NOT_PENDING(
             HttpStatus.BAD_REQUEST, "미션 기록의 이미지 업로드 상태가 PENDING이 아닙니다."),
     MISSION_RECORD_ALREADY_EXISTS_TODAY(HttpStatus.BAD_REQUEST, "오늘 이미 작성 된 미션 기록이 존재합니다."),
+
+    // Follow
+    FOLLOW_TARGET_MEMBER_NOT_FOUND(HttpStatus.NOT_FOUND, "타겟 유저을 찾을 수 없습니다."),
+    FOLLOW_ALREADY_EXIST(HttpStatus.BAD_REQUEST, "이미 팔로우 중인 회원입니다."),
+    FOLLOW_NOT_EXIST(HttpStatus.BAD_REQUEST, "팔로우 중인 회원만 팔로우 취소가 가능합니다."),
     ;
 
     private final HttpStatus status;

src/test/java/com/depromeet/domain/follow/api/FollowControllerTest.java

@@ -0,0 +1,111 @@
+package com.depromeet.domain.follow.api;
+
+import static org.junit.jupiter.api.Assertions.*;
+import static org.springframework.http.MediaType.APPLICATION_JSON;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.delete;
+import static org.springframework.test.web.servlet.request.MockMvcRequestBuilders.post;
+import static org.springframework.test.web.servlet.result.MockMvcResultHandlers.print;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.jsonPath;
+import static org.springframework.test.web.servlet.result.MockMvcResultMatchers.status;
+
+import com.depromeet.domain.follow.application.FollowService;
+import com.depromeet.domain.follow.dto.request.FollowCreateRequest;
+import com.depromeet.domain.follow.dto.request.FollowDeleteRequest;
+import com.depromeet.global.security.JwtAuthenticationFilter;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import org.junit.jupiter.api.Nested;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.web.servlet.AutoConfigureMockMvc;
+import org.springframework.boot.test.autoconfigure.web.servlet.WebMvcTest;
+import org.springframework.boot.test.mock.mockito.MockBean;
+import org.springframework.data.jpa.mapping.JpaMetamodelMappingContext;
+import org.springframework.http.HttpStatus;
+import org.springframework.test.web.servlet.MockMvc;
+
+@WebMvcTest(FollowController.class)
+@AutoConfigureMockMvc(addFilters = false)
+@MockBean({JpaMetamodelMappingContext.class, JwtAuthenticationFilter.class})
+class FollowControllerTest {
+    @Autowired private MockMvc mockMvc;
+    @Autowired private ObjectMapper objectMapper;
+    @MockBean private FollowService followService;
+
+    @Nested
+    class 팔로우를_추가할_때 {
+        @Test
+        void targetId가_NULL_이라면_예외를_발생시킨다() throws Exception {
+            // given
+            FollowCreateRequest request = new FollowCreateRequest(null);
+
+            // when, then
+            mockMvc.perform(
+                            post("/follows")
+                                    .contentType(APPLICATION_JSON)
+                                    .content(objectMapper.writeValueAsString(request)))
+                    .andExpect(status().isBadRequest())
+                    .andExpect(jsonPath("$.success").value(false))
+                    .andExpect(jsonPath("$.status").value(HttpStatus.BAD_REQUEST.value()))
+                    .andExpect(
+                            jsonPath("$.data.errorClassName")
+                                    .value("MethodArgumentNotValidException"))
+                    .andExpect(jsonPath("$.data.message").value("타겟 아이디는 비워둘 수 없습니다."))
+                    .andDo(print());
+        }
+
+        @Test
+        void 입력_값이_정상이라면_예외가_발생하지_않는다() throws Exception {
+            // given
+            FollowCreateRequest request = new FollowCreateRequest(21L);
+
+            // when, then
+            mockMvc.perform(
+                            post("/follows")
+                                    .contentType(APPLICATION_JSON)
+                                    .content(objectMapper.writeValueAsString(request)))
+                    .andExpect(status().isCreated())
+                    .andExpect(jsonPath("$.success").value(true))
+                    .andExpect(jsonPath("$.status").value(HttpStatus.CREATED.value()))
+                    .andDo(print());
+        }
+    }
+
+    @Nested
+    class 팔로우를_취소할_때 {
+        @Test
+        void targetId가_NULL_이라면_예외를_발생시킨다() throws Exception {
+            // given
+            FollowDeleteRequest request = new FollowDeleteRequest(null);
+
+            // when, then
+            mockMvc.perform(
+                            delete("/follows")
+                                    .contentType(APPLICATION_JSON)
+                                    .content(objectMapper.writeValueAsString(request)))
+                    .andExpect(status().isBadRequest())
+                    .andExpect(jsonPath("$.success").value(false))
+                    .andExpect(jsonPath("$.status").value(HttpStatus.BAD_REQUEST.value()))
+                    .andExpect(
+                            jsonPath("$.data.errorClassName")
+                                    .value("MethodArgumentNotValidException"))
+                    .andExpect(jsonPath("$.data.message").value("타겟 아이디는 비워둘 수 없습니다."))
+                    .andDo(print());
+        }
+
+        @Test
+        void 입력_값이_정상이라면_예외가_발생하지_않는다() throws Exception {
+            // given
+            FollowDeleteRequest request = new FollowDeleteRequest(21L);
+
+            // when, then
+            mockMvc.perform(
+                            delete("/follows")
+                                    .contentType(APPLICATION_JSON)
+                                    .content(objectMapper.writeValueAsString(request)))
+                    .andExpect(status().isOk())
+                    .andExpect(jsonPath("$.success").value(true))
+                    .andExpect(jsonPath("$.status").value(HttpStatus.OK.value()))
+                    .andDo(print());
+        }
+    }
+}