def test_abbreviatingDistinguishedNames(self):
        """
        Check that abbreviations used in certificates correctly map to
        complete names.
        """
        self.assertEqual(
                sslverify.DN(CN=b'a', OU=b'hello'),
                sslverify.DistinguishedName(commonName=b'a',
                                            organizationalUnitName=b'hello'))
        self.assertNotEqual(
                sslverify.DN(CN=b'a', OU=b'hello'),
                sslverify.DN(CN=b'a', OU=b'hello', emailAddress=b'xxx'))
        dn = sslverify.DN(CN=b'abcdefg')
        self.assertRaises(AttributeError, setattr, dn, 'Cn', b'x')
        self.assertEqual(dn.CN, dn.commonName)
        dn.CN = b'bcdefga'
        self.assertEqual(dn.CN, dn.commonName)

        Check that abbreviations used in certificates correctly map to
        complete names.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sslverify.py