def test_userRejectedHostKey(self):
        """
        If the L{KnownHostsFile} instance used to construct
        L{SSHCommandClientEndpoint} rejects the SSH public key presented by the
        server, the L{Deferred} returned by L{SSHCommandClientEndpoint.connect}
        fires with a L{Failure} wrapping L{UserRejectedKey}.
        """
        endpoint = SSHCommandClientEndpoint.newConnection(
            self.reactor, b"/bin/ls -l", b"dummy user",
            self.hostname, self.port, knownHosts=KnownHostsFile(self.mktemp()),
            ui=FixedResponseUI(False))

        factory = Factory()
        factory.protocol = Protocol
        connected = endpoint.connect(factory)

        server, client, pump = self.connectedServerAndClient(
            self.factory, self.reactor.tcpClients[0][2])

        f = self.failureResultOf(connected)
        f.trap(UserRejectedKey)

        If the L{KnownHostsFile} instance used to construct
        L{SSHCommandClientEndpoint} rejects the SSH public key presented by the
        server, the L{Deferred} returned by L{SSHCommandClientEndpoint.connect}
        fires with a L{Failure} wrapping L{UserRejectedKey}.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/test/test_endpoints.py