AutoAppConfigTest에 관한 질문 입니다.

강의에서 MemberService가 아닌 구현체인 MemberServiceImpl을 빈으로 등록한 뒤에

getBean을 통해서 호출할 때, 구현체가 아닌 인터페이스 타입으로도 검색이 되는 이유가 다형성 때문일까요?

그리고 인터페이스의 이름으로 빈이 호출이 안되는 이유는 인터페이스를 직접 빈에 등록하지 않았기 때문으로 이해를 하면 될까요?

아래는 강의관련 코드 입니다. 설정영역코드는 생략 하였습니다.

package hello.core.scan;

import hello.core.AutoAppConfig;
import hello.core.member.MemberService;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;

import static org.assertj.core.api.Assertions.*;

public class AutoAppConfigTest {

    @Test
    void basicScan() {
        AnnotationConfigApplicationContext ac = new AnnotationConfigApplicationContext(AutoAppConfig.class);

        MemberService memberService = ac.getBean(MemberService.class);
        assertThat(memberService).isInstanceOf(MemberService.class);
    }
} 

package hello.core.member;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
public class MemberServiceImpl implements MemberService {

    private final MemberRepository memberRepository;

    @Autowired
    public MemberServiceImpl(MemberRepository memberRepository) {
        this.memberRepository = memberRepository;
    }

    @Override

    public void join(Member member) {
        memberRepository.save(member);
    }

    @Override
    public Member findMember(Long memberId) {
        return memberRepository.findById(memberId);
    }

    //테스트 용도
    public MemberRepository getMemberRepository() {
        return memberRepository;
    }
}

package hello.core.member;

import org.springframework.stereotype.Component;


public interface MemberService {

    void join(Member member);

    Member findMember(Long memberId);
}

MemberService memberService = ac.getBean("memberServiceImpl",MemberService.class);
assertThat(memberService).isInstanceOf(MemberService.class);