code: def test_polycompanion_zero_dim(self, dtype):
      for xp in (numpy, cupy):
          a = testing.shaped_random((), xp, dtype)
          with pytest.raises(ValueError):
              xp.polynomial.polynomial.polycompanion(a)
  
imports: import unittest
  import numpy
  import pytest
  import cupy
  from cupy import testing
label_desc: Use image node_id 18 for calling the TestPolynomial obj's underlying member method code with example usage: obj.test_polycompanion_zero_dim(dtype) without return types