text: from unittest import TestCase
  
  import pandas as pd
  from pandas.testing import assert_frame_equal, assert_index_equal
  
  import category_encoders as encoders
  
  
  class TestHashingEncoder(TestCase):
      def test_must_not_reset_index(self):
          columns = ['column1', 'column2', 'column3', 'column4']
          df = pd.DataFrame([[i, i, i, i] for i in range(10)], columns=columns)
          df = df.iloc[2:8, :]
          target_columns = ['column1', 'column2', 'column3']
  
          single_process_encoder = encoders.HashingEncoder(max_process=1, cols=target_columns)
          single_process_encoder.fit(df, None)
          df_encoded_single_process = single_process_encoder.transform(df)
          assert_index_equal(df.index, df_encoded_single_process.index)
          assert df.shape[0] == pd.concat([df, df_encoded_single_process], axis=1).shape[0]
  
          multi_process_encoder = encoders.HashingEncoder(cols=target_columns)
          multi_process_encoder.fit(df, None)
          df_encoded_multi_process = multi_process_encoder.transform(df)
          assert_index_equal(df.index, df_encoded_multi_process.index)
          assert df.shape[0] == pd.concat([df, df_encoded_multi_process], axis=1).shape[0]
  
          assert_frame_equal(df_encoded_single_process, df_encoded_multi_process)
  