code: def test_get_value_function(self):
      with mock.patch(
          NO, new_callable=mock.PropertyMock
      ) as mock_num_outputs:
          mock_num_outputs.return_value = 1
          mm = MockModel(None)
          # test PosteriorMean
          vf = _get_value_function(mm)
          # test initialization
          self.assertIn("model", vf._modules)
          self.assertEqual(vf._modules["model"], mm)
  
          self.assertIsInstance(vf, PosteriorMean)
          self.assertIsNone(vf.posterior_transform)
          # test SimpleRegret
          obj = GenericMCObjective(lambda Y, X: Y.sum(dim=-1))
          sampler = IIDNormalSampler(sample_shape=torch.Size([2]))
          vf = _get_value_function(
              model=mm, objective=obj, sampler=sampler
          )
          self.assertIsInstance(vf, qSimpleRegret)
          self.assertEqual(vf.objective, obj)
          self.assertEqual(vf.sampler, sampler)
          # test with project
          mock_project = mock.Mock(
              return_value=torch.ones(1, 1, 1, device=self.device)
          )
          vf = _get_value_function(
              model=mm,
              objective=obj,
              sampler=sampler,
              project=mock_project,
          )
          self.assertIsInstance(vf, ProjectedAcquisitionFunction)
          self.assertEqual(vf.objective, obj)
          self.assertEqual(vf.sampler, sampler)
          self.assertEqual(vf.project, mock_project)
          test_X = torch.rand(1, 1, 1, device=self.device)
          with mock.patch.object(
              vf,
              "base_value_function",
              __class__=torch.nn.Module,
              return_value=None,
          ) as patch_bvf:
              vf(test_X)
              mock_project.assert_called_once_with(test_X)
              patch_bvf.assert_called_once_with(
                  torch.ones(1, 1, 1, device=self.device)
              )
  
imports: from contextlib import ExitStack
  from unittest import mock
  import torch
  from botorch.acquisition.analytic import PosteriorMean, ScalarizedPosteriorMean
  from botorch.acquisition.cost_aware import GenericCostAwareUtility
  from botorch.acquisition.knowledge_gradient import _get_value_function, _split_fantasy_points, ProjectedAcquisitionFunction, qKnowledgeGradient, qMultiFidelityKnowledgeGradient
  from botorch.acquisition.monte_carlo import qExpectedImprovement, qSimpleRegret
  from botorch.acquisition.objective import GenericMCObjective, ScalarizedPosteriorTransform
  from botorch.acquisition.utils import project_to_sample_points
  from botorch.exceptions.errors import UnsupportedError
  from botorch.generation.gen import gen_candidates_scipy
  from botorch.models import SingleTaskGP
  from botorch.optim.optimize import optimize_acqf
  from botorch.optim.utils import _filter_kwargs
  from botorch.posteriors.gpytorch import GPyTorchPosterior
  from botorch.sampling.normal import IIDNormalSampler, SobolQMCNormalSampler
  from botorch.utils.test_helpers import DummyNonScalarizingPosteriorTransform
  from botorch.utils.testing import BotorchTestCase, MockModel, MockPosterior
  from gpytorch.distributions import MultitaskMultivariateNormal
label_desc: Use image node_id 1 for calling the TestKGUtils obj's underlying member method code with example usage: obj.test_get_value_function() without return types