code: def test_unique_empty_return_all_no_axis(self, xp, dtype):
      a = xp.empty((3, 0, 2), dtype)
      return xp.unique(
          a, return_index=True, return_inverse=True, return_counts=True
      )
  
imports: import unittest
  import pytest
  import numpy
  import cupy
  from cupy import testing
label_desc: Use image node_id 13 for calling the TestUnique obj's underlying member method code with example usage: obj.test_unique_empty_return_all_no_axis(xp, dtype) and returns: xp