docstr: Test that acquisition function returns correct weighted acquisition
          
code: def test_acquisition_function(self):
      """Test that acquisition function returns correct weighted acquisition"""
      self.mock_model.predict.return_value = (
          [1, 2, 3, 4],
          [3, 3, 3, 3],
      )
      self.mock_model.get_fmin.return_value = [0.1, 0.2, 0.3, 0.4]
  
      weighted_acquisition = (
          self.ei_mcmc_acquisition.acquisition_function(
              np.array([2, 2])
          )
      )
  
      self.assertTrue(
          np.isclose(
              weighted_acquisition,
              np.array([[-0.44634968], [-0.44634968]]),
          ).all()
      )
  
file_path: GPyOpt/GPyOpt/testing/acquisitions_tests/test_ei_mcmc_acquisition.py
imports: import unittest
  from mock import Mock
  import numpy
  from GPyOpt.acquisitions import AcquisitionEI_MCMC
  from GPyOpt.core.task.space import Design_space
label_desc: Use image node_id 2 for calling the TestEImcmcAcquisition obj's underlying member method code with example usage: obj.test_acquisition_function() without return types