'When a client requests a subsystem, the SSHSession object should get
the subsystem by calling avatar.lookupSubsystem, and attach it as
the client.'

def test_lookupSubsystem(self):

    ret = self.session.requestReceived('subsystem', (common.NS('TestSubsystem') + 'data'))
    self.assertTrue(ret)
    self.assertIsInstance(self.session.client, protocol.ProcessProtocol)
    self.assertIs(self.session.client.transport.proto, self.session.avatar.subsystem)
