def test_trustRootSpecificCertificate(self):
        """
        Specifying a L{Certificate} object for L{trustRoot} will result in that
        certificate being the only trust root for a client.
        """
        caCert, serverCert = certificatesForAuthorityAndServer()
        otherCa, otherServer = certificatesForAuthorityAndServer()
        sProto, cProto, sWrapped, cWrapped, pump = loopbackTLSConnection(
            trustRoot=caCert,
            privateKeyFile=pathContainingDumpOf(self, serverCert.privateKey),
            chainedCertFile=pathContainingDumpOf(self, serverCert),
        )
        pump.flush()
        self.assertIsNone(cWrapped.lostReason)
        self.assertEqual(cWrapped.data,
                         sWrapped.greeting)

        Specifying a L{Certificate} object for L{trustRoot} will result in that
        certificate being the only trust root for a client.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/test/test_sslverify.py