def METHOD_NAME(self):
    geo = "county"
    weekday = False
    numtype = "covid"
    today = datetime(2020, 6, 4)
    fn = "changehc_covid_from_20200601_to_20200604.parquet"
    assert fn not in os.listdir(backfill_dir)
    merge_backfill_file(backfill_dir, numtype, geo, weekday, today.weekday(),
                        today, test_mode=True, check_nd=2)         
    assert fn not in os.listdir(backfill_dir)
    # Generate backfill daily files     
    for d in range(1, 5):
        dropdate = datetime(2020, 6, d)        
        store_backfill_file(combined_data, dropdate, backfill_dir, \
                            numtype, geo, weekday)
    # Check the when the merged file is not generated
    today = datetime(2020, 6, 4)
    merge_backfill_file(backfill_dir, numtype, geo, weekday, today.weekday(),
                        today, test_mode=True, check_nd=8)
    assert fn not in os.listdir(backfill_dir)
    # Generate the merged file, but not delete it
    merge_backfill_file(backfill_dir, numtype, geo, weekday, today.weekday(),
                        today, test_mode=True, check_nd=2)         
    assert fn in os.listdir(backfill_dir)
    # Read daily file
    new_files = glob.glob(backfill_dir + "/changehc_%s*.parquet"%numtype)
    pdList = []        
    for file in new_files:
        if "from" in file:
            continue
        df = pd.read_parquet(file, engine='pyarrow')
        pdList.append(df)
        os.remove(file)
    new_files = glob.glob(backfill_dir + "/changehc_%s*.parquet"%numtype)
    assert len(new_files) == 1
    expected = pd.concat(pdList).sort_values(["time_value", "fips"])
    # Read the merged file
    merged = pd.read_parquet(backfill_dir + "/" + fn, engine='pyarrow')
    assert set(expected.columns) == set(merged.columns)
    assert expected.shape[0] == merged.shape[0]
    assert expected.shape[1] == merged.shape[1]
    os.remove(backfill_dir + "/" + fn)
    assert fn not in os.listdir(backfill_dir)