def test_ListLineFormatter(self):
        """
        Test that the function which formats the lines in response to a LIST
        command does so appropriately.
        """
        listLines = list(pop3.formatListResponse([]))
        self.assertEqual(
            listLines,
            [b'+OK 0\r\n', b'.\r\n'])

        listLines = list(pop3.formatListResponse([1, 2, 3, 100]))
        self.assertEqual(
            listLines,
            [b'+OK 4\r\n', b'1 1\r\n', b'2 2\r\n', b'3 3\r\n', b'4 100\r\n',
             b'.\r\n'])

        Test that the function which formats the lines in response to a LIST
        command does so appropriately.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/mail/test/test_pop3.py