code: def test_sort_index(self):
      pdf = pd.DataFrame(
          {"x": [2, 1, np.nan]}, index=["b", "a", np.nan]
      )
      psdf = ps.from_pandas(pdf)
  
      pser = pdf.x
      psser = psdf.x
  
      # Assert invalid parameters
      self.assertRaises(
          NotImplementedError, lambda: psser.sort_index(axis=1)
      )
      self.assertRaises(
          NotImplementedError,
          lambda: psser.sort_index(kind="mergesort"),
      )
      self.assertRaises(
          ValueError, lambda: psser.sort_index(na_position="invalid")
      )
  
      # Assert default behavior without parameters
      self.assert_eq(psser.sort_index(), pser.sort_index())
      # Assert sorting descending
      self.assert_eq(
          psser.sort_index(ascending=False),
          pser.sort_index(ascending=False),
      )
      # Assert sorting NA indices first
      self.assert_eq(
          psser.sort_index(na_position="first"),
          pser.sort_index(na_position="first"),
      )
      # Assert ignoring index
      self.assert_eq(
          psser.sort_index(ignore_index=True),
          pser.sort_index(ignore_index=True),
      )
  
      # Assert sorting inplace
      # pandas sorts pdf.x by the index and update the column only
      # when the Series is derived from DataFrame.
      psser.sort_index(inplace=True)
      self.assert_eq(psser, pser.sort_index())
      self.assert_eq(psdf, pdf)
  
      # pandas sorts pdf.x by the index and update the column only
      # when the Series is derived from DataFrame.
      psser.sort_index(inplace=True, ascending=False, ignore_index=True)
      self.assert_eq(
          psser, pser.sort_index(ascending=False, ignore_index=True)
      )
      self.assert_eq(psdf, pdf)
  
      pser = pdf.x.copy()
      psser = psdf.x.copy()
  
      psser.sort_index(inplace=True)
      pser.sort_index(inplace=True)
      self.assert_eq(psser, pser)
      self.assert_eq(psdf, pdf)
  
      # Assert multi-indices
      pser = pd.Series(
          range(4), index=[["b", "b", "a", "a"], [1, 0, 1, 0]], name="0"
      )
      psser = ps.from_pandas(pser)
      self.assert_eq(psser.sort_index(), pser.sort_index())
      self.assert_eq(
          psser.sort_index(level=[1, 0]), pser.sort_index(level=[1, 0])
      )
  
      self.assert_eq(
          psser.reset_index().sort_index(),
          pser.reset_index().sort_index(),
      )
  
file_path: spark/python/pyspark/pandas/tests/series/test_sort.py
imports: import unittest
  import numpy
  import pandas
  from pyspark import pandas
  from pyspark.testing.pandasutils import ComparisonTestBase
  from pyspark.testing.sqlutils import SQLTestUtils
label_desc: Use image node_id 2 for calling the SeriesSortMixin obj's underlying member method code with example usage: obj.test_sort_index() without return types