code: def test_best_trial_str():
      t = Trial("__fake", stub=True)
      t.trial_id = "18ae7_00005"
      t.run_metadata.last_result = {
          "loss": 0.5918508041056858,
          "config": {"train_loop_config": {"lr": 0.059253447253394785}},
      }
      assert (
          _best_trial_str(t, "loss")
          == "Current best trial: 18ae7_00005 with loss=0.5918508041056858"
          " and params={'train_loop_config': {'lr': 0.059253447253394785}}"
      )
  
imports: import argparse
  from unittest import mock
  import pytest
  import sys
  from freezegun import freeze_time
  from ray import tune
  from ray.air.constants import TRAINING_ITERATION
  from ray.tune.experimental.output import _get_time_str, _get_trials_by_state, _get_trial_info, _infer_user_metrics, _max_len, _current_best_trial, _best_trial_str, _get_trial_table_data, _get_dict_as_table_data, _infer_params, AirVerbosity, TrainReporter, TuneTerminalReporter
  from ray.tune.experiment.trial import Trial
label_desc: Use image node_id 6 for calling a global function with example usage: test_best_trial_str() without return types