code: def test_concatenate_columns_errors(dataframe, column_names):
      """
      Test that an error is raised when less than two columns are specified.
      """
      with pytest.raises(
          JanitorError, match="At least two columns must be specified"
      ):
          dataframe.concatenate_columns(
              column_names=column_names, new_column_name="index"
          )
  
imports: import pytest
  from janitor.errors import JanitorError
label_desc: Use image node_id 3 for calling a global function with example usage: test_concatenate_columns_errors(dataframe, column_names) without return types