new_contents: import unittest
  
  import cupy
  from cupy import cuda
  from cupy import testing
  from cupy import elementwise
  
  
  @testing.gpu
  class TestElementwise(unittest.TestCase):
  
      _multiprocess_can_split_ = True
  
      def check_copy(self, dtype, src_id, dst_id):
          with cuda.Device(src_id):
              src = testing.shaped_arange((2, 3, 4), dtype=dtype)
          with cuda.Device(dst_id):
              dst = cupy.empty((2, 3, 4), dtype=dtype)
          elementwise.copy(src, dst)
          testing.assert_allclose(src, dst)
  
      @testing.for_all_dtypes()
      def test_copy(self, dtype):
          device_id = cuda.Device().id
          self.check_copy(dtype, device_id, device_id)
  
      @testing.multi_gpu(2)
      @testing.for_all_dtypes()
      def test_copy_multigpu(self, dtype):
          with self.assertRaises(ValueError):
              self.check_copy(dtype, 0, 1)
  
  
subject: Add unittests for elementwise.copy