code: def test_optimizer_base_estimator_string_invalid(base_estimator):
      """Check that error is raised when `Optimizer` is given an invalid `base_estimator` string"""
      err = r"Expected `base_estimator` in \['GP', 'ET', 'RF', 'GBRT', 'DUMMY'\]\. Got {}".format(
          base_estimator
      )
      with pytest.raises(ValueError, match=err):
          Optimizer(
              [(-2.0, 2.0)],
              base_estimator=base_estimator,
              n_initial_points=1,
          )
  
imports: from hyperparameter_hunter.optimization.backends.skopt.engine import Optimizer
  import numpy
  import pytest
  from scipy.optimize import OptimizeResult
  from sklearn.multioutput import MultiOutputRegressor
  from sklearn.utils.testing import assert_array_equal
  from skopt.benchmarks import bench1, bench1_with_time
  from skopt.learning import ExtraTreesRegressor, RandomForestRegressor
  from skopt.learning import GradientBoostingQuantileRegressor
label_desc: Use image node_id 10 for calling a global function with example usage: test_optimizer_base_estimator_string_invalid(base_estimator) without return types