SpringBoot整合单元测试&&关于SpringBoot单元测试找不到Mapper和Service报java.lang.NullPointerException的错误

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

import org.junit.Test;
@RunWith(SpringRunner.class)
@SpringBootTest(classes = EduApplication.class)
public class MyTest {
    @Autowired
    private EduCourseMapper courseMapper;
    @Test
    public void testdemo01(){
        courseMapper.deleteById("1655898309098749953");
        System.out.println("springboot单元测试");
    }
}