new_contents: from itertools import combinations
  from string import ascii_lowercase
  
  from botbot import checkinfo as ci
  
  def test_bidirectional_problem_serialization(tmpdir):
      info = ci.CheckResult(tmpdir.strpath)
      for probs in combinations(ascii_lowercase, 3):
          info.add_problem(''.join(probs))
  
      old_probs = info.problems
  
      ps = info.serialize_problems()
      info.decode_probstr(ps)
      assert info.problems == old_probs
  
subject: Add new test for CheckResult