code: def test_interp_alt_scipy(self):
      pytest.importorskip("scipy")
      df = DataFrame(
          {
              "A": [1, 2, np.nan, 4, 5, np.nan, 7],
              "C": [1, 2, 3, 5, 8, 13, 21],
          }
      )
      result = df.interpolate(method="barycentric")
      expected = df.copy()
      expected.loc[2, "A"] = 3
      expected.loc[5, "A"] = 6
      tm.assert_frame_equal(result, expected)
  
      msg = "The 'downcast' keyword in DataFrame.interpolate is deprecated"
      with tm.assert_produces_warning(FutureWarning, match=msg):
          result = df.interpolate(
              method="barycentric", downcast="infer"
          )
      tm.assert_frame_equal(result, expected.astype(np.int64))
  
      result = df.interpolate(method="krogh")
      expectedk = df.copy()
      expectedk["A"] = expected["A"]
      tm.assert_frame_equal(result, expectedk)
  
      result = df.interpolate(method="pchip")
      expected.loc[2, "A"] = 3
      expected.loc[5, "A"] = 6.0
  
      tm.assert_frame_equal(result, expected)
  
imports: import numpy
  import pytest
  from pandas._config import using_pyarrow_string_dtype
  from pandas.errors import ChainedAssignmentError
  import pandas.util._test_decorators
  from pandas import DataFrame, NaT, Series, date_range
  import pandas._testing
label_desc: Use image node_id 12 for calling the TestDataFrameInterpolate obj's underlying member method code with example usage: obj.test_interp_alt_scipy() without return types