code: def test_get_dow_grouped_suffix():
      """Tests `get_dow_grouped_suffix` function."""
      date = pd.to_datetime("2023-01-01")
      assert get_dow_grouped_suffix(date) == "_Sun"
  
      date = pd.to_datetime("2023-01-02")
      assert get_dow_grouped_suffix(date) == "_Mon/Fri"
  
      date = pd.to_datetime("2023-01-03")
      assert get_dow_grouped_suffix(date) == "_WD"
  
      date = pd.to_datetime("2023-01-04")
      assert get_dow_grouped_suffix(date) == "_WD"
  
      date = pd.to_datetime("2023-01-05")
      assert get_dow_grouped_suffix(date) == "_WD"
  
      date = pd.to_datetime("2023-01-06")
      assert get_dow_grouped_suffix(date) == "_Mon/Fri"
  
      date = pd.to_datetime("2023-01-07")
      assert get_dow_grouped_suffix(date) == "_Sat"
  
file_path: greykite/greykite/tests/algo/common/test_holiday_utils.py
imports: import pandas
  import pytest
  from greykite.algo.common.holiday_utils import add_shifted_events
  from greykite.algo.common.holiday_utils import get_autoreg_holiday_interactions
  from greykite.algo.common.holiday_utils import get_dow_grouped_suffix
  from greykite.algo.common.holiday_utils import get_weekday_weekend_suffix
  from greykite.common.constants import EVENT_DF_DATE_COL
  from greykite.common.constants import EVENT_DF_LABEL_COL
label_desc: Use image node_id 1 for calling a global function with example usage: test_get_dow_grouped_suffix() without return types