code: def test_get_data_names():
      dl = DataLoader()
      # Returns empty set as there is no .csv file in 'data' folder
      data_path = dl.get_data_home()
      file_names = dl.get_data_names(data_path=data_path)
      assert file_names == []
  
      data_path = dl.get_data_home(data_sub_dir="daily")
      file_names = dl.get_data_names(data_path=data_path)
      assert set(file_names) == {
          "daily_temperature_australia",
          "daily_demand_order",
          "daily_female_births",
          "daily_hierarchical_actuals",
          "daily_hierarchical_forecasts",
          "daily_istanbul_stock",
          "daily_peyton_manning",
          "daily_bitcoin_transactions",
      }
  
imports: import os
  import re
  import pandas
  import pytest
  from greykite.common.constants import TIME_COL
  from greykite.common.data_loader import DataLoader
  from greykite.common.testing_utils import assert_equal
label_desc: Use image node_id 3 for calling a global function with example usage: test_get_data_names() without return types