new_contents: import unittest
  try:
      from unittest import mock
  except ImportError:
      import mock  # < PY33
  
  from flake8.util import option_normalizer
  
  class TestOptionSerializer(unittest.TestCase):
  
      def test_true(self):
          option = option_normalizer('1')
          self.assertEqual(option, True)
  
          option = option_normalizer('T')
          self.assertEqual(option, True)
  
          option = option_normalizer('TRUE')
          self.assertEqual(option, True)
  
          option = option_normalizer('ON')
          self.assertEqual(option, True)
  
          option = option_normalizer('t')
          self.assertEqual(option, True)
  
          option = option_normalizer('true')
          self.assertEqual(option, True)
  
          option = option_normalizer('on')
          self.assertEqual(option, True)
  
      def test_false(self):
          option = option_normalizer('0')
          self.assertEqual(option, False)
  
          option = option_normalizer('F')
          self.assertEqual(option, False)
  
          option = option_normalizer('FALSE')
          self.assertEqual(option, False)
  
          option = option_normalizer('OFF')
          self.assertEqual(option, False)
  
          option = option_normalizer('f')
          self.assertEqual(option, False)
  
          option = option_normalizer('false')
          self.assertEqual(option, False)
  
          option = option_normalizer('off')
          self.assertEqual(option, False)
  
      def test_multiple_option(self):
          answer = ['F401', 'F402', 'F403', 'F404']
  
          option = option_normalizer('F401,F402,F403,F404')
          self.assertEqual(option, answer)
  
          option = option_normalizer('F401 ,F402 ,F403 ,F404')
          self.assertEqual(option, answer)
  
          option = option_normalizer('F401, F402, F403, F404')
          self.assertEqual(option, answer)
  
          option = option_normalizer('''\
              F401,
              F402,
              F403,
              F404,
          ''')
          self.assertEqual(option, answer)
  
  
  if __name__ == '__main__':
      unittest.main()
  
subject: Add option_normalizer test code