code: def test_invalid(self, nonchx_backend_config, chx_backend_config):
      assert nonchx_backend_config.xp is not chainerx
      assert chx_backend_config.xp is chainerx
  
      self.check_invalid(
          nonchx_backend_config.device, chx_backend_config.device
      )
      self.check_invalid(
          chx_backend_config.device, nonchx_backend_config.device
      )
      # cuda.DummyDevice is not supported either.
      self.check_invalid(chx_backend_config.device, cuda.DummyDevice)
  
imports: import unittest
  import numpy
  import pytest
  import chainer
  from chainer import backend
  from chainer.backends import _cpu
  from chainer.backends import cuda
  from chainer import functions
  from chainer import testing
  import chainerx
label_desc: Use image node_id 2 for calling the TestCopyBetweenChainerxAndNonChainerx obj's underlying member method code with example usage: obj.test_invalid(nonchx_backend_config, chx_backend_config) without return types