code: def test__randtobest1(self):
      # strategies randtobest/1/*
      result = np.array([0.15])
      trial = self.dummy_solver2._randtobest1((2, 3, 4, 5, 6))
      assert_allclose(trial, result)
  
imports: import multiprocessing
  from scipy.optimize import _differentialevolution
  from scipy.optimize._differentialevolution import DifferentialEvolutionSolver
  from scipy.optimize import differential_evolution
  import numpy
  from scipy.optimize import rosen
  from numpy.testing import assert_equal, assert_allclose, assert_almost_equal, assert_string_equal, assert_
  from pytest import raises, warns
label_desc: Use image node_id 7 for calling the TestDifferentialEvolutionSolver obj's underlying member method code with example usage: obj.test__randtobest1() without return types