code: def test_clearsky_trafo_vals():
      """Tests clear sky trafo with and without missing values and period index."""
      y = load_solar(api_version=None)
      # only take every 4H for quickness
      y = y.asfreq("4H")
      cs_model = ClearSky()
      y_trafo = cs_model.fit_transform(y)
  
      msg = "ClearSky not transforming values consistently with stored values."
      assert np.all(output_chk == y_trafo[0:6].round(3).tolist()), msg
  
      y_missing = y.copy()
      y_missing.iloc[6:12] = np.nan
      cs_model_missing = ClearSky()
      y_trafo_missing = cs_model_missing.fit_transform(y_missing)
  
      msg = (
          "ClearSky transformer not returning correct number of values."
      )
      assert y.count() == y_trafo.count(), msg
      assert y_missing.count() == y_trafo_missing.count(), msg
  
      y_period = y.copy()
      y_period.index = y_period.index.to_period()
      cs_model_period = ClearSky()
      y_trafo_period = cs_model_period.fit_transform(y_period)
  
      msg = "PeriodIndex and DatetimeIndex returning different values"
      assert np.all(y_trafo_period.values == y_trafo.values), msg
  
file_path: sktime/sktime/transformations/series/tests/test_clear_sky.py
imports: import numpy
  import pandas
  import pytest
  from sktime.datasets import load_solar
  from sktime.tests.test_switch import run_test_for_class
  from sktime.transformations.series.clear_sky import ClearSky
label_desc: Use image node_id 1 for calling a global function with example usage: test_clearsky_trafo_vals() without return types