code: def test_basic_vstack(self):
      A, B = self.data()
  
      actual = _construct.vstack([A, B]).todense()
      testing.assert_array_equal(actual, self.expected())
  
imports: import functools
  import re
  from unittest import mock
  import numpy
  import pytest
  import cupy
  from cupy import testing
  from cupy.cuda import runtime
  from cupyx.scipy import sparse
  from cupyx.scipy.sparse import _construct
label_desc: Use image node_id 3 for calling the TestVstack obj's underlying member method code with example usage: obj.test_basic_vstack() without return types