code: def test_astype_invalid_geodataframe():
      # https://github.com/geopandas/geopandas/issues/1144
      # a GeoDataFrame without geometry column should not error in astype
      df = GeoDataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
      res = df.astype(object)
      assert isinstance(res, pd.DataFrame) and not isinstance(
          res, GeoDataFrame
      )
      assert res["a"].dtype == object
  
imports: import os
  from packaging.version import Version
  import warnings
  import numpy
  from numpy.testing import assert_array_equal
  import pandas
  import shapely
  from shapely.geometry import Point, GeometryCollection, LineString, LinearRing
  import geopandas
  from geopandas import GeoDataFrame, GeoSeries
  import geopandas._compat
  from geopandas.array import from_shapely
  from geopandas.testing import assert_geodataframe_equal, assert_geoseries_equal
  from pandas.testing import assert_frame_equal, assert_series_equal
  import pytest
label_desc: Use image node_id 15 for calling a global function with example usage: test_astype_invalid_geodataframe() without return types