code: def test_to_frame_expanddim(self):
      # GH#9762
  
      class SubclassedSeries(Series):
          @property
          def _constructor_expanddim(self):
              return SubclassedFrame
  
      class SubclassedFrame(DataFrame):
          pass
  
      ser = SubclassedSeries([1, 2, 3], name="X")
      result = ser.to_frame()
      assert isinstance(result, SubclassedFrame)
      expected = SubclassedFrame({"X": [1, 2, 3]})
      tm.assert_frame_equal(result, expected)
  
imports: import pytest
  from pandas import DataFrame, Index, Series
  import pandas._testing
label_desc: Use image node_id 3 for calling the TestToFrame obj's underlying member method code with example usage: obj.test_to_frame_expanddim() and returns: SubclassedFrame