code: def _check_forward_internal(
      self, dst_device_spec, src_device, dst_device, x_mode
  ):
      x = src_device.send(self.x)
  
      if x_mode == "array":
          pass
      elif x_mode == "non_requires_grad":
          x = chainer.Variable(x, requires_grad=False)
      elif x_mode == "requires_grad":
          x = chainer.Variable(x, requires_grad=True)
      else:
          assert False, x_mode
  
      error_expected = (src_device.xp is chainerx) != (
          dst_device.xp is chainerx
      ) and x_mode == "requires_grad"
      if error_expected:
          with pytest.raises(RuntimeError):
              functions.copy(x, dst_device_spec)
          return
  
      y = functions.copy(x, dst_device_spec)
  
      assert y.device == dst_device
      assert backend.get_device_from_array(y.array) == dst_device
      assert y.dtype == self.dtype
      numpy.testing.assert_array_equal(
          _numpy_device.send(y.array), self.x
      )
  
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 CopyTestBase obj's underlying member method code with example usage: obj._check_forward_internal(dst_device_spec, src_device, dst_device, x_mode) without return types