code: def test_get_public_domain_text(df):
      df["publish_time"] = ""
      df["authors"] = ""
      df["journal"] = ""
      df["abstract"] = ""
  
      def mock_retrieve_text(
          row,
          container_name,
          azure_storage_account_name,
          azure_storage_sas_token,
      ):
          return "full text"
  
      with patch(
          "recommenders.datasets.covid_utils.retrieve_text",
          side_effect=mock_retrieve_text,
      ):
          full = get_public_domain_text(df, container_name="test")
  
      assert all(full["full_text"] == ["full text"] * 5)
  
file_path: recommenders/tests/data_validation/recommenders/datasets/test_covid_utils.py
imports: from unittest.mock import patch
  import pytest
  from recommenders.datasets.covid_utils import remove_duplicates, remove_nan, clean_dataframe, retrieve_text, get_public_domain_text
  import numpy
  import pandas
label_desc: Use image node_id 6 for calling a global function with example usage: test_get_public_domain_text(df) and returns: str