class_docstr: Fixture generator for forecasting tests.
  
  Fixtures parameterized
  ----------------------
  estimator_class: estimator inheriting from BaseObject
      ranges over all estimator classes not excluded by EXCLUDED_TESTS
  estimator_instance: instance of estimator inheriting from BaseObject
      ranges over all estimator classes not excluded by EXCLUDED_TESTS
      instances are generated by create_test_instance class method
  scenario: instance of TestScenario
      ranges over all scenarios returned by retrieve_scenarios
class_docstr_tok: ["Fixture","generator","for","forecasting","tests",".","Fixtures","parameterized","--","--","--","--","--","--","--","--","--","--","--","estimator_class",":","estimator","inheriting","from","BaseObject","ranges","over","all","estimator","classes","not","excluded","by","EXCLUDED_TESTS","estimator_instance",":","instance","of","estimator","inheriting","from","BaseObject","ranges","over","all","estimator","classes","not","excluded","by","EXCLUDED_TESTS","instances","are","generated","by","create_test_instance","class","method","scenario",":","instance","of","TestScenario","ranges","over","all","scenarios","returned","by","retrieve_scenarios"]
docstr: Return step length for window.
  
  Fixtures parameterized
  ----------------------
  step_length: int
      1 if update_params=True; TEST_STEP_LENGTH_INT if update_params=False
docstr_tok: ["Return","step","length","for","window",".","Fixtures","parameterized","--","--","--","--","--","--","--","--","--","--","--","step_length",":","int","1","if","update_params=True",";","TEST_STEP_LENGTH_INT","if","update_params=False"]
code: def _generate_step_length(self, test_name, **kwargs):
      """Return step length for window.
  
      Fixtures parameterized
      ----------------------
      step_length: int
          1 if update_params=True; TEST_STEP_LENGTH_INT if update_params=False
      """
      update_params = kwargs["update_params"]
      if update_params:
          return [1], [""]
      else:
          return TEST_STEP_LENGTHS_INT, [
              f"step={a}" for a in TEST_STEP_LENGTHS_INT
          ]
  
imports: import numpy
  import pandas
  import pytest
  from sktime.datatypes import check_is_mtype
  from sktime.datatypes._utilities import get_cutoff
  from sktime.exceptions import NotFittedError
  from sktime.forecasting.base._delegate import _DelegatedForecaster
  from sktime.forecasting.base._fh import ForecastingHorizon
  from sktime.forecasting.tests._config import TEST_ALPHAS, TEST_FHS, TEST_OOS_FHS, TEST_STEP_LENGTHS_INT, TEST_WINDOW_LENGTHS_INT, VALID_INDEX_FH_COMBINATIONS
  from sktime.performance_metrics.forecasting import mean_absolute_percentage_error
  from sktime.split import ExpandingWindowSplitter, SlidingWindowSplitter, temporal_train_test_split
  from sktime.tests.test_all_estimators import BaseFixtureGenerator, QuickTester
  from sktime.utils._testing.forecasting import _assert_correct_columns, _assert_correct_pred_time_index, _get_expected_index_for_update_predict, _get_n_columns, _make_fh, make_forecasting_problem
  from sktime.utils._testing.series import _make_series
  from sktime.utils.validation.forecasting import check_fh
label_desc: Use image node_id 3 for calling the ForecasterFixtureGenerator obj's underlying member method code with example usage: obj._generate_step_length(test_name) and returns: list,  list, TEST_STEP_LENGTHS_INT,  unknown