code: def test_seasonality_inference(
      self, freq_string: str, expected_seasonal_periods: int
  ):
      series = tg.sine_timeseries(length=200, freq=freq_string)
      model = ExponentialSmoothing()
      model.fit(series)
      assert model.seasonal_periods == expected_seasonal_periods
  
file_path: darts/darts/tests/models/forecasting/test_exponential_smoothing.py
imports: import numpy
  import pytest
  from darts import TimeSeries
  from darts.models import ExponentialSmoothing
  from darts.utils import timeseries_generation
label_desc: Use image node_id 1 for calling the TestExponentialSmoothing obj's underlying member method code with example usage: obj.test_seasonality_inference(freq_string, expected_seasonal_periods) without return types