code: def setup_method(self):
      self.old_seterr = np.seterr(invalid="raise")
      self.limits = np.array([[0.0, 0.0], [2.0, 2.0]])
      self.bounds = [(0.0, 2.0), (0.0, 2.0)]
  
      self.dummy_solver = DifferentialEvolutionSolver(
          self.quadratic, [(0, 100)]
      )
  
      # dummy_solver2 will be used to test mutation strategies
      self.dummy_solver2 = DifferentialEvolutionSolver(
          self.quadratic, [(0, 1)], popsize=7, mutation=0.5
      )
      # create a population that's only 7 members long
      # [0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7]
      population = np.atleast_2d(np.arange(0.1, 0.8, 0.1)).T
      self.dummy_solver2.population = population
  
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 1 for calling the TestDifferentialEvolutionSolver obj's underlying member method code with example usage: obj.setup_method() without return types