code: def test_astype(xp, shape, device, copy, src_dtype, dst_dtype):
      a = array_utils.create_dummy_ndarray(xp, shape, src_dtype)
  
      # Casting negative value to unsigned int behaves different in CUDA
      if (
          device.name == "cuda:0"
          and src_dtype in chainerx.testing.signed_dtypes
          and dst_dtype in chainerx.testing.unsigned_dtypes
      ):
          a = xp.maximum(a, 0)
  
      b = a.astype(dst_dtype, copy=copy)
      assert (
          a is b if src_dtype == dst_dtype and not copy else a is not b
      )
      return b
  
imports: import copy
  import math
  import pickle
  import numpy
  import pytest
  import chainerx
  import chainerx.testing
  from chainerx_tests import array_utils
label_desc: Use image node_id 13 for calling a global function with example usage: test_astype(xp, shape, device, copy, src_dtype, dst_dtype) and returns: b