code: def test_parallel(self):
      # smoke test for parallelization with deferred updating
      bounds = [(0.0, 2.0), (0.0, 2.0)]
      with multiprocessing.Pool(2) as p, DifferentialEvolutionSolver(
          rosen, bounds, updating="deferred", workers=p.map
      ) as solver:
          assert_(solver._mapwrapper.pool is not None)
          assert_(solver._updating == "deferred")
          solver.solve()
  
      with DifferentialEvolutionSolver(
          rosen, bounds, updating="deferred", workers=2
      ) as solver:
          assert_(solver._mapwrapper.pool is not None)
          assert_(solver._updating == "deferred")
          solver.solve()
  
imports: import multiprocessing
  import platform
  from scipy.optimize._differentialevolution import DifferentialEvolutionSolver, _ConstraintWrapper
  from scipy.optimize import differential_evolution
  from scipy.optimize._constraints import Bounds, NonlinearConstraint, LinearConstraint
  from scipy.optimize import rosen
  from scipy.sparse import csr_matrix
  from scipy._lib._pep440 import Version
  import numpy
  from numpy.testing import assert_equal, assert_allclose, assert_almost_equal, assert_array_equal, assert_string_equal, assert_, suppress_warnings
  from pytest import raises, warns
  import pytest
label_desc: Use image node_id 38 for calling the TestDifferentialEvolutionSolver obj's underlying member method code with example usage: obj.test_parallel() without return types