code: def test_dia(self):
      x = sparse.dia_matrix(
          (cupy.array([], "f"), cupy.array([0], "i")),
          shape=(0, 0),
          dtype="f",
      )
      assert sparse.isspmatrix_dia(x) is True
  
imports: import pickle
  import unittest
  import numpy
  import pytest
  import cupy
  from cupy import testing
  from cupy.cuda import driver
  from cupy.cuda import runtime
  from cupyx.scipy import sparse
label_desc: Use image node_id 1 for calling the TestIsspmatrixDia obj's underlying member method code with example usage: obj.test_dia() without return types