code: def test_Gen(self, mock_init, mock_gen):
      # Test with constraints
      # pyre-fixme[20]: Argument `model` expected.
      modelbridge = RandomModelBridge()
      modelbridge.parameters = ["x", "y", "z"]
      modelbridge.transforms = OrderedDict()
      modelbridge.model = RandomModel()
      gen_results = modelbridge._gen(
          n=3,
          search_space=self.search_space,
          pending_observations={},
          fixed_features=ObservationFeatures({"z": 3.0}),
          optimization_config=None,
          # pyre-fixme[6]: For 6th param expected `Optional[Dict[str, Union[None,
          #  Dict[str, typing.Any], OptimizationConfig, AcquisitionFunction, float,
          #  int, str]]]` but got `Dict[str, str]`.
          model_gen_options=self.model_gen_options,
      )
      gen_args = mock_gen.mock_calls[0][2]
      self.assertEqual(gen_args["n"], 3)
      self.assertEqual(
          gen_args["bounds"], [(0.0, 1.0), (1.0, 2.0), (0.0, 5.0)]
      )
      self.assertTrue(
          np.array_equal(
              gen_args["linear_constraints"][0],
              np.array([[1.0, -1, 0.0], [-1.0, 0.0, -1.0]]),
          )
      )
      self.assertTrue(
          np.array_equal(
              gen_args["linear_constraints"][1],
              np.array([[0.0], [-3.5]]),
          )
      )
      self.assertEqual(gen_args["fixed_features"], {2: 3.0})
      self.assertEqual(gen_args["model_gen_options"], {"option": "yes"})
      obsf = gen_results.observation_features
      self.assertEqual(
          obsf[0].parameters, {"x": 1.0, "y": 2.0, "z": 3.0}
      )
      self.assertEqual(
          obsf[1].parameters, {"x": 3.0, "y": 4.0, "z": 3.0}
      )
      self.assertTrue(
          np.array_equal(gen_results.weights, np.array([1.0, 2.0]))
      )
  
      # Test with no constraints, no fixed feature, no pending observations
      search_space = SearchSpace(self.parameters[:2])
      modelbridge.parameters = ["x", "y"]
      modelbridge._gen(
          n=3,
          search_space=search_space,
          pending_observations={},
          fixed_features=ObservationFeatures({}),
          optimization_config=None,
          # pyre-fixme[6]: For 6th param expected `Optional[Dict[str, Union[None,
          #  Dict[str, typing.Any], OptimizationConfig, AcquisitionFunction, float,
          #  int, str]]]` but got `Dict[str, str]`.
          model_gen_options=self.model_gen_options,
      )
      gen_args = mock_gen.mock_calls[1][2]
      self.assertEqual(gen_args["bounds"], [(0.0, 1.0), (1.0, 2.0)])
      self.assertIsNone(gen_args["linear_constraints"])
      self.assertIsNone(gen_args["fixed_features"])
  
imports: from collections import OrderedDict
  from unittest import mock
  import numpy
  from ax.core.observation import ObservationFeatures
  from ax.core.parameter import ParameterType, RangeParameter
  from ax.core.parameter_constraint import OrderConstraint, SumConstraint
  from ax.core.search_space import SearchSpace
  from ax.exceptions.core import SearchSpaceExhausted
  from ax.modelbridge.random import RandomModelBridge
  from ax.modelbridge.registry import Cont_X_trans
  from ax.models.random.base import RandomModel
  from ax.models.random.sobol import SobolGenerator
  from ax.utils.common.testutils import TestCase
  from ax.utils.testing.core_stubs import get_small_discrete_search_space
label_desc: Use image node_id 5 for calling the RandomModelBridgeTest obj's underlying member method code with example usage: obj.test_Gen(mock_init, mock_gen) without return types