java.lang.NullPointerException: Cannot invoke “com.atguigu.mapper(because “this.userMapper“ is null)

记录一下一个错误。学习mybatisplus中遇到的：

java.lang.NullPointerException: Cannot invoke "com.atguigu.mapper.UserMapper.selectList(com.baomidou.mybatisplus.core.conditions.Wrapper)" because "this.userMapper" is null

解决办法就是加一个注解

@SpringBootTest