'Previously, if one only wanted to implement a subsystem, an ISession
adapter wasn\'t needed because subsystems were looked up using the
lookupSubsystem method on the avatar.'

def test_lookupSubsystemDoesNotNeedISession(self):

    s = session.SSHSession(avatar=SubsystemOnlyAvatar(), conn=StubConnection())
    ret = s.request_subsystem((common.NS('subsystem') + 'data'))
    self.assertTrue(ret)
    self.assertIsNotNone(s.client)
    self.assertIsNone(s.conn.closes.get(s))
    s.eofReceived()
    self.assertTrue(s.conn.closes.get(s))
    s.loseConnection()
    s.closed()
