code: def test_getitem_bool_mask_categorical_index(self):
      df3 = DataFrame(
          {
              "A": np.arange(6, dtype="int64"),
          },
          index=CategoricalIndex(
              [1, 1, 2, 1, 3, 2],
              dtype=CategoricalDtype([3, 2, 1], ordered=True),
              name="B",
          ),
      )
      df4 = DataFrame(
          {
              "A": np.arange(6, dtype="int64"),
          },
          index=CategoricalIndex(
              [1, 1, 2, 1, 3, 2],
              dtype=CategoricalDtype([3, 2, 1], ordered=False),
              name="B",
          ),
      )
  
      result = df3[df3.index == "a"]
      expected = df3.iloc[[]]
      tm.assert_frame_equal(result, expected)
  
      result = df4[df4.index == "a"]
      expected = df4.iloc[[]]
      tm.assert_frame_equal(result, expected)
  
      result = df3[df3.index == 1]
      expected = df3.iloc[[0, 1, 3]]
      tm.assert_frame_equal(result, expected)
  
      result = df4[df4.index == 1]
      expected = df4.iloc[[0, 1, 3]]
      tm.assert_frame_equal(result, expected)
  
      # since we have an ordered categorical
  
      # CategoricalIndex([1, 1, 2, 1, 3, 2],
      #         categories=[3, 2, 1],
      #         ordered=True,
      #         name='B')
      result = df3[df3.index < 2]
      expected = df3.iloc[[4]]
      tm.assert_frame_equal(result, expected)
  
      result = df3[df3.index > 1]
      expected = df3.iloc[[]]
      tm.assert_frame_equal(result, expected)
  
      # unordered
      # cannot be compared
  
      # CategoricalIndex([1, 1, 2, 1, 3, 2],
      #         categories=[3, 2, 1],
      #         ordered=False,
      #         name='B')
      msg = "Unordered Categoricals can only compare equality or not"
      with pytest.raises(TypeError, match=msg):
          df4[df4.index < 2]
      with pytest.raises(TypeError, match=msg):
          df4[df4.index > 1]
  
imports: import re
  import numpy
  import pytest
  from pandas import Categorical, CategoricalDtype, CategoricalIndex, DataFrame, DateOffset, DatetimeIndex, Index, MultiIndex, Series, Timestamp, concat, date_range, get_dummies, period_range
  import pandas._testing
  from pandas.core.arrays import SparseArray
label_desc: Use image node_id 1 for calling the TestGetitemBooleanMask obj's underlying member method code with example usage: obj.test_getitem_bool_mask_categorical_index() without return types