[스프링 입문] 회원서비스 개발 및 테스트

📌 회원 서비스 개발

package hello.hellospring.service;

import hello.hellospring.domain.Member;
import hello.hellospring.repository.MemberRepository;

import java.util.List;
import java.util.Optional;

public class MemberService {

    private final MemberRepository memberRepository;

    public MemberService(MemberRepository memberRepository){
        this.memberRepository = memberRepository;
    }

    /*
     * 회원 가입
     */
    public Long join(Member member){
        validateDuplicateMember(member);  // 중복 회원 검증
        memberRepository.save(member);
        return member.getId();

    }

    private void validateDuplicateMember(Member member) {
        memberRepository.findByName(member.getName())
            .ifPresent(m ->{
            throw new IllegalStateException("이미 존재하는 회원입니다.");
        });
    }

    /*
     * 전체 회원 조회
     */
    public List<Member> findMembers(){
        return memberRepository.findAll();
    }

    public Optional<Member> findOne(Long memberId){
        return memberRepository.findById(memberId);
    }

}

📌 회원 서비스 테스트

package hello.hellospring.service;

import hello.hellospring.domain.Member;
import hello.hellospring.repository.MemberRepository;
import hello.hellospring.repository.MemoryMemberRepository;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;

import static org.junit.jupiter.api.Assertions.*;

class MemberServiceTest {

    MemberService memberService;
    MemoryMemberRepository memberRepository = new MemoryMemberRepository();

    @BeforeEach
    public void beforeEach(){
        memberRepository = new MemoryMemberRepository();
        memberService = new MemberService(memberRepository);
    }

    @AfterEach
    public void afterEach(){
        memberRepository.clearStore();
    }

    @Test
    void 회원가입() {
        // given
        Member member = new Member();
        member.setName("hello");

        // when
        Long saveId = memberService.join(member);

        // then
        Member findMember = memberService.findOne(saveId).get();
        Assertions.assertThat(member.getName()).isEqualTo(findMember.getName());

    }

    @Test
    public void 중복_회원_예외(){
        // given
        Member member1 = new Member();
        member1.setName("spring");

        Member member2 = new Member();
        member2.setName("spring");

        // when
        memberService.join(member1);
        IllegalStateException e = assertThrows(IllegalStateException.class, () -> memberService.join(member2));

        Assertions.assertThat(e.getMessage()).isEqualTo("이미 존재하는 회원입니다.");

    }
}

@BeforeEach : 각 테스트 실행 전에 호출된다. 테스트가 서로 영향이 없도록 항상 새로운 객체를 생성하고, 의존관계도를 새로 맺어준다.