def test_sslDHparameters(self):
        """
        If C{dhParameters} are specified, they are passed as
        L{DiffieHellmanParameters} into L{CertificateOptions}.
        """
        fileName = 'someFile'
        reactor = object()
        server = endpoints.serverFromString(
            reactor,
            "ssl:4321:privateKey={0}:certKey={1}:dhParameters={2}"
            .format(escapedPEMPathName, escapedPEMPathName, fileName)
        )
        cf = server._sslContextFactory
        self.assertIsInstance(cf.dhParameters, DiffieHellmanParameters)
        self.assertEqual(FilePath(fileName), cf.dhParameters._dhFile)

        If C{dhParameters} are specified, they are passed as
        L{DiffieHellmanParameters} into L{CertificateOptions}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/internet/test/test_endpoints.py