code: def test__mutate2(self):
      # strategies */2/*, i.e. rand/2/bin, best/2/exp, etc.
      # [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7]
  
      result = np.array([-0.1])
      trial = self.dummy_solver2._best2((2, 3, 4, 5, 6))
      assert_allclose(trial, result)
  
      result = np.array([0.1])
      trial = self.dummy_solver2._rand2((2, 3, 4, 5, 6))
      assert_allclose(trial, result)
  
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 6 for calling the TestDifferentialEvolutionSolver obj's underlying member method code with example usage: obj.test__mutate2() without return types