code: def test_concat_sorts_index(self, sort):
      df1 = DataFrame({"a": [1, 2, 3]}, index=["c", "a", "b"])
      df2 = DataFrame({"b": [1, 2]}, index=["a", "b"])
  
      # For True/None
      expected = DataFrame(
          {"a": [2, 3, 1], "b": [1, 2, None]},
          index=["a", "b", "c"],
          columns=["a", "b"],
      )
      if sort is False:
          expected = expected.loc[["c", "a", "b"]]
  
      # Warn and sort by default
      with tm.assert_produces_warning(None):
          result = pd.concat([df1, df2], axis=1, sort=sort)
      tm.assert_frame_equal(result, expected)
  
file_path: pandas/pandas/tests/reshape/concat/test_sort.py
imports: import numpy
  import pytest
  import pandas
  from pandas import DataFrame
  import pandas._testing
label_desc: Use image node_id 2 for calling the TestConcatSort obj's underlying member method code with example usage: obj.test_concat_sorts_index(sort) without return types