'Ensure that closed objects can not be used again.'

def testClose(self):

    client = aff4.FACTORY.Create(self.client_id, aff4_grr.VFSGRRClient, mode='w', token=self.token)
    client.Close()
    self.assertRaises(IOError, client.Get, client.Schema.HOSTNAME)
    self.assertRaises(IOError, client.Set, client.Schema.HOSTNAME('hello'))
