### Question:
UserDao { public int deleteById(Integer id) { return template.update("DELETE FROM users WHERE id = ?", id); }  int insert(UserDO entity); int insert0(UserDO entity); int updateById(UserDO entity); int deleteById(Integer id); UserDO selectById(Integer id); UserDO selectByUsername(String username); List<UserDO> selectByIds(List<Integer> ids);  }### Answer:
@Test public void testDeleteById() { userDao.deleteById(2); }