code: def test_inv(matrices):
      A_dense, A_sparse, b = matrices
      x0 = splin.inv(sp.csc_matrix(A_dense))
      x = splin.inv(A_sparse)
      assert_allclose(x.toarray(), x0.toarray())
  
imports: import pytest
  import numpy
  import scipy.sparse
  import scipy.sparse.linalg
  from numpy.testing import assert_allclose, assert_equal
label_desc: Use image node_id 17 for calling a global function with example usage: test_inv(matrices) without return types