def test_givesMeaningfulErrorMessageIfNoCipherMatches(self):
        """
        If there is no valid cipher that matches the user's wishes,
        a L{ValueError} is raised.
        """
        self.assertRaises(
            ValueError,
            sslverify.OpenSSLCertificateOptions,
            privateKey=self.sKey,
            certificate=self.sCert,
            acceptableCiphers=
            sslverify.OpenSSLAcceptableCiphers.fromOpenSSLCipherString('')
        )

        If there is no valid cipher that matches the user's wishes,
        a L{ValueError} is raised.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sslverify.py