code: def test_ffill(self):
      ts = Series(
          [0.0, 1.0, 2.0, 3.0, 4.0],
          index=date_range("2020-01-01", periods=5),
      )
      ts.iloc[2] = np.nan
      tm.assert_series_equal(ts.ffill(), ts.fillna(method="ffill"))
  
imports: from datetime import datetime, timedelta, timezone
  import numpy
  import pytest
  import pytz
  from pandas import Categorical, DataFrame, DatetimeIndex, NaT, Period, Series, Timedelta, Timestamp, date_range, isna, timedelta_range
  import pandas._testing
  from pandas.core.arrays import period_array
label_desc: Use image node_id 2 for calling the TestFillnaPad obj's underlying member method code with example usage: obj.test_ffill() without return types