code: def test_process_df(df):
      """Tests adjust trend and aggregation."""
      model = SeasonalityInferrer()
      df_adj = model._process_df(
          df=df,
          time_col=cst.TIME_COL,
          value_col=cst.VALUE_COL,
          adjust_trend_method=TrendAdjustMethodEnum.seasonal_average.value,
          adjust_trend_params=None,
          aggregation_period="W-SUN",
      )
      assert infer_freq(df_adj, cst.TIME_COL) == "W-SUN"
  
file_path: greykite/greykite/tests/algo/common/test_seasonality_inferrer.py
imports: from copy import deepcopy
  import pandas
  import pytest
  from greykite.algo.common.seasonality_inferrer import SeasonalityInferConfig
  from greykite.algo.common.seasonality_inferrer import SeasonalityInferrer
  from greykite.algo.common.seasonality_inferrer import TrendAdjustMethodEnum
  from greykite.common import constants
  from greykite.common.testing_utils import assert_equal
  from greykite.common.testing_utils import generate_df_for_tests
  from greykite.common.time_properties import infer_freq
label_desc: Use image node_id 8 for calling a global function with example usage: test_process_df(df) without return types