code: def test_create_study() -> None:
      study = optuna.multi_objective.create_study(["maximize"])
      assert study.n_objectives == 1
      assert study.directions == [StudyDirection.MAXIMIZE]
  
      study = optuna.multi_objective.create_study(
          ["maximize", "minimize"]
      )
      assert study.n_objectives == 2
      assert study.directions == [
          StudyDirection.MAXIMIZE,
          StudyDirection.MINIMIZE,
      ]
  
      with pytest.raises(ValueError):
          # Empty `directions` isn't allowed.
          study = optuna.multi_objective.create_study([])
  
file_path: optuna/tests/multi_objective_tests/test_study.py
imports: from typing import List
  from typing import Tuple
  import uuid
  import _pytest.capture
  import pytest
  import optuna
  from optuna.study._study_direction import StudyDirection
  from optuna.testing.storages import StorageSupplier
label_desc: Use image node_id 1 for calling a global function with example usage: test_create_study() without return types