code: def test_should_return_df_empty_columns():
      assert pp.rename(
          df=categories_df,
          columns={},
      ).equals(categories_df)
  
file_path: superset/tests/unit_tests/pandas_postprocessing/test_rename.py
imports: import pandas
  import pytest
  from superset.exceptions import InvalidPostProcessingError
  from superset.utils import pandas_postprocessing
  from tests.unit_tests.fixtures.dataframes import categories_df
label_desc: Use image node_id 9 for calling a global function with example usage: test_should_return_df_empty_columns() without return types