old_contents: # -*- coding:utf-8 -*-
  from __future__ import absolute_import, division, print_function, unicode_literals
  import pytest
  
  from bs4 import BeautifulSoup
  from hfut_stu_lib import parser
  
  
  class TestParser(object):
      def test_parse_tr_strs(self):
          single_tag = "<tr><td>Fuck!</td></tr>"
          assert parser.parse_tr_strs(BeautifulSoup(single_tag, 'lxml').tr) == ['Fuck!']
          wrong_tag = "<tr><td><font>Fuck!<font/><font>You!<font/></td></tr>"
          with pytest.raises(ValueError):
              parser.parse_tr_strs(BeautifulSoup(wrong_tag, 'lxml').tr)
  
new_contents: # -*- coding:utf-8 -*-
  from __future__ import absolute_import, division, print_function, unicode_literals
  import pytest
  
  from bs4 import BeautifulSoup
  from hfut_stu_lib import parser, BaseSession
  
  
  class TestParser(object):
      def test_parse_tr_strs(self):
          single_tag = "<tr><td>Fuck!</td></tr>"
          assert parser.parse_tr_strs(BeautifulSoup(single_tag, 'lxml').tr) == ['Fuck!']
          wrong_tag = "<tr><td><font>Fuck!<font/><font>You!<font/></td></tr>"
          with pytest.raises(ValueError):
              parser.parse_tr_strs(BeautifulSoup(wrong_tag, BaseSession.html_parser).tr)
  
subject: fix testcase