def test_day_counts(il_electricity_cdd_hdd_billing_monthly):
data = il_electricity_cdd_hdd_billing_monthly["meter_data"].value
counts = day_counts(data.index)
assert counts.shape == (27, )
assert counts.iloc[0] == 29.0
assert pd.isnull(counts.iloc[-1])
assert counts.sum() == 790.0
def test_day_counts_empty_series():
index = pd.DatetimeIndex([])
index.freq = None
data = pd.Series([], index=index)
counts = day_counts(data.index)
assert counts.shape == (0, )