### Question:
CommonServiceImpl implements CommonService { @Override @LogMethod("查看用户名是否存在") public boolean existsUsername(String username) { return userDAO.existsByUsername(username); } @Autowired  CommonServiceImpl(UserDAO userDAO); @Override @LogMethod("查看用户名是否存在") boolean existsUsername(String username); @Override @LogMethod("查看邮箱是否存在") boolean existsEmail(String email);  }### Answer:
@Test public void existsUsername() { Assert.assertFalse(commonService.existsUsername(RandomUtil.randomString(16))); }