new_contents: from botbot import sqlcache
  
  import os
  from itertools import combinations
  from string import ascii_letters
  
  def get_dbpath():
      return os.path.join('.', 'test.db')
  
  def test_FileDatabase_constructor(tmpdir):
      prev = tmpdir.chdir()
  
      f = sqlcache.FileDatabase(get_dbpath())
      assert f
      prev.chdir()
  
  def test_bidirectional_problem_serialization():
      for probs in combinations(ascii_letters, 3):
          fi = {'problems': set(probs)}
          sqlcache.serialize_problems(fi)
          sqlcache.decode_problems(fi)
          assert fi['problems'] == set(probs)
  
  def test_db_finders(tmpdir):
      prev = tmpdir.chdir()
  
      tmp = sqlcache.get_dbpath
      sqlcache.get_dbpath = get_dbpath
      assert not sqlcache.db_exists()
      tmpdir.join(get_dbpath()).ensure(file=True)
      assert sqlcache.db_exists()
      sqlcache.get_dbpath = tmp
  
      prev.chdir()
  
subject: Add new tests for sqlcache.py