new_contents: from prismriver import preprocessor
  
  test_cases = [('Artist', 'Title', 'Artist', 'Title'),
                ('  Artist', '  Title', 'Artist', 'Title'),
                ('Artist ', 'Title ', 'Artist', 'Title'),
                (' Artist ', ' Title ', 'Artist', 'Title')]
  
  
  def test():
      for params in test_cases:
          yield check_em, params[0], params[1], params[2], params[3]
  
  
  def check_em(artist: str, title: str, clean_artist: str, clean_title: str):
      (processed_artist, processed_title) = preprocessor.apply(artist, title, ['trim'])
      assert processed_artist == clean_artist
      assert processed_title == clean_title
  
subject: Add test case for preprocessor