def METHOD_NAME(self):
    self.fmt.device = self.loop_devices[0]
    # create and open the luks format
    self.fmt.create()
    self.fmt.setup()
    self.addCleanup(self._luks_close)
    # without update_size_info size should be 0
    self.assertEqual(self.fmt.current_size, Size(0))
    # get current size
    self.fmt.update_size_info()
    self.assertGreater(self.fmt.current_size, Size(0))