code: def test_spline(self):
      pytest.importorskip("scipy")
      s = Series([1, 2, np.nan, 4, 5, np.nan, 7])
      result = s.interpolate(method="spline", order=1)
      expected = Series([1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0])
      tm.assert_series_equal(result, expected)
  
imports: import numpy
  import pytest
  import pandas.util._test_decorators
  import pandas
  from pandas import Index, MultiIndex, Series, date_range, isna
  import pandas._testing
label_desc: Use image node_id 40 for calling the TestSeriesInterpolateData obj's underlying member method code with example usage: obj.test_spline() without return types