assertj의 Assertions 를 못가져옵니다..ㅠㅠ

assertj의 assertThat을 사용하시는데...저는 임포트가 안됩니다.

아래는 MemberRepositoryTest 소스입니다.

package jpabook.jpashop;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

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


@RunWith(SpringRunner.class)
@SpringBootTest
public class MemberRepositoryTest {

    @Autowired MemberRepository memberRepository;

    @Test
    public void testMember() throws Exception {
        // given
        Member member = new Member();
        member.setUsername("memberA");

        // when
        Long saveId = memberRepository.save(member);
        Member findMember = memberRepository.find(saveId);

        // then

//        Assertions.assertThat(findMember.getId()).isEqualTo(member.getId());
    }
}

강의에서는 junit을 따로 gradle에 추가해주시지 않았지만 저는 RunWith 등의 오류가 나서

gradle에 junit을 추가해주었습니다.

같은 방식으로 assertj를 추가해주었는데.. Assertions를 사용하진 못하고 있습니다.

build.gradle 입니다.

plugins {
   id 'org.springframework.boot' version '2.6.5'
   id 'io.spring.dependency-management' version '1.0.11.RELEASE'
   id 'java'
}

group = 'jpabook'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '11'

configurations {
   compileOnly {
      extendsFrom annotationProcessor
   }
}

repositories {
   mavenCentral()
}

dependencies {
   implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
   implementation 'org.springframework.boot:spring-boot-starter-thymeleaf'
   implementation 'org.springframework.boot:spring-boot-starter-web'
   implementation 'org.springframework.boot:spring-boot-devtools'
   compileOnly 'org.projectlombok:lombok'
   runtimeOnly 'com.h2database:h2'
   annotationProcessor 'org.projectlombok:lombok'
   testImplementation 'org.springframework.boot:spring-boot-starter-test'
   testImplementation 'junit:junit:4.12'
   testImplementation 'org.assertj:assertj-core:3.21.0'
// testImplementation group: 'org.assertj', name: 'assertj-core', version: '3.21.0'
// implementation 'junit:junit:4.12'
}

tasks.named('test') {
   useJUnitPlatform()
}