code: def test_copy(self, dtype):
      device_id = cuda.Device().id
      self.check_copy(dtype, device_id, device_id)
  
imports: import unittest
  import numpy
  import pytest
  import cupy
  from cupy import _core
  from cupy import cuda
  from cupy import testing
label_desc: Use image node_id 2 for calling the TestElementwise obj's underlying member method code with example usage: obj.test_copy(dtype) without return types