def test_pad_nan(self):
x = TimeSeries([np.nan, 1., np.nan, 3., np.nan],
['z', 'a', 'b', 'c', 'd'], dtype=float)
x = x.fillna(method='pad')
expected = TimeSeries([np.nan, 1.0, 1.0, 3.0, 3.0],
['z', 'a', 'b', 'c', 'd'], dtype=float)
assert_series_equal(x[1:], expected[1:])
self.assert_(np.isnan(x[0]), np.isnan(expected[0]))
