def test_stringTypeError(self):
        """
        If things is a string, a TypeError is raised.
        """
        sample = "One, two, three"
        error = self.assertRaises(TypeError, util._listToPhrase, sample, 'and')
        self.assertEqual(str(error), "Things must be a list or a tuple")

        If things is a string, a TypeError is raised.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/trial/test/test_util.py