code: def test_best_solution_retrieval(self):
      # test that the getter property method for the best solution works.
      solver = DifferentialEvolutionSolver(self.quadratic, [(-2, 2)])
      result = solver.solve()
      assert_almost_equal(result.x, solver.x)
  
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 15 for calling the TestDifferentialEvolutionSolver obj's underlying member method code with example usage: obj.test_best_solution_retrieval() without return types