첫번째 querydsl테스트 코드 에서 nullpointexception이 터졌습니다

[질문 템플릿]
1. 강의 내용과 관련된 질문인가요? (예/아니오)
2. 인프런의 질문 게시판과 자주 하는 질문에 없는 내용인가요? (예/아니오)
3. 질문 잘하기 메뉴얼을 읽어보셨나요? (예/아니오)

[질문 내용]
여기에 질문 내용을 남겨주세요.

q타입을 생성하고 import를 해주었습니다.

package study.querydsl;


import com.querydsl.jpa.impl.JPAQueryFactory;
import org.assertj.core.api.Assertions;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.transaction.annotation.Transactional;
import study.querydsl.entity.Member;
import study.querydsl.entity.Team;

import javax.persistence.EntityManager;

import static study.querydsl.entity.QMember.*;

@SpringBootTest
@Transactional
public class QuerydslBasicTest {


    @Autowired
    EntityManager em;

    JPAQueryFactory queryFactory;

    @BeforeEach
    public void before() {

        Team teamA = new Team("teamA");
        Team teamB = new Team("teamB");
        em.persist(teamA);
        em.persist(teamB);


        Member member1 = new Member("member1", 10, teamA);
        Member member2 = new Member("member2", 20, teamA);
        Member member3 = new Member("member3", 30, teamA);
        Member member4 = new Member("member4", 40, teamA);
        em.persist(member1);
        em.persist(member2);
        em.persist(member3);
        em.persist(member4);

    }
    @Test
    public void startJPQL() {
        String qlString = "select m from Member m" +
                " where m.username = :username";
        Member findMember = em.createQuery(qlString, Member.class)
                .setParameter("username", "member1")
                .getSingleResult();

        Assertions.assertThat(findMember.getUsername()).isEqualTo("member1");
    }

    @Test
    public void startQuerydsl() {
        Member findMember = queryFactory
                .select(member)
                .from(member)
                .where(member.username.eq("member1"))
                .fetchOne();
        Assertions.assertThat(findMember.getUsername()).isEqualTo("member1");
    }

}

queryFactory = new JPAQueryFactory(em);