code: def test_update_stop_metadata(self) -> None:
      self.assertEqual(len(self.trial.stop_metadata), 1)
      old_stop_metadata = deepcopy(self.trial.stop_metadata)
      self.trial.update_stop_metadata({"something": "new"})
      self.assertEqual(
          self.trial.stop_metadata,
          {**old_stop_metadata, "something": "new"},
      )
  
imports: import itertools
  from copy import deepcopy
  from unittest import mock
  from unittest.mock import Mock, patch
  import pandas
  from ax.core.base_trial import BaseTrial, TrialStatus
  from ax.core.data import Data
  from ax.core.generator_run import GeneratorRun, GeneratorRunType
  from ax.core.runner import Runner
  from ax.exceptions.core import UserInputError
  from ax.runners.synthetic import SyntheticRunner
  from ax.utils.common.result import Ok
  from ax.utils.common.testutils import TestCase
  from ax.utils.testing.core_stubs import get_arms, get_branin_arms, get_experiment, get_objective, get_test_map_data_experiment
label_desc: Use image node_id 16 for calling the TrialTest obj's underlying member method code with example usage: obj.test_update_stop_metadata() without return types