### Question:
CommentService { public Page<CommentDto> findCommentByCondition(CommentDto commentDto, Pageable pageable) { Specification<Comment> condition = (root, query, builder) -> { List<Predicate> predicates = new ArrayList<>(); if (StringUtils.isNotEmpty(commentDto.getContent())) { predicates.add(builder.like(root.get("content"), "%" + commentDto.getContent() + "%")); } return query.where(predicates.toArray(new Predicate[0])).getRestriction(); }; return commentDao.findAll(condition, pageable).map(commentMapper::toDto); } CommentService(CommentDao commentDao, CommentMapper commentMapper); Page<CommentDto> findCommentByCondition(CommentDto commentDto, Pageable pageable); CommentDto findCommentByPrimaryKey(String commentId); void saveOrUpdate(CommentDto commentDto); void deleteCommentByIds(List<String> commentIds);  }### Answer:
@Test void testFindCommentByCondition() { Page<CommentDto> result = commentService.findCommentByCondition(new CommentDto(), null); Assertions.assertEquals(null, result); }