class_docstr: Basic tests on the display_data.py example.
code: def test_sparse_tfidf_multiworkers(self):
      with testing_utils.tempdir() as tmpdir:
          MODEL_FILE = os.path.join(tmpdir, "tmp_test_babi")
          testing_utils.train_model(
              dict(
                  model="tfidf_retriever",
                  task="babi:task1k:1",
                  model_file=MODEL_FILE,
                  retriever_numworkers=4,
                  retriever_hashsize=2**8,
                  retriever_tokenizer="simple",
                  datatype="train:ordered",
                  batchsize=1,
                  num_epochs=1,
              )
          )
  
          agent = create_agent_from_model_file(MODEL_FILE)
  
          obs = {
              "text": (
                  "Mary moved to the bathroom. John went to the hallway. "
                  "Where is Mary?"
              ),
              "episode_done": True,
          }
          agent.observe(obs)
          reply = agent.act()
          assert reply["text"] == "bathroom"
  
          ANS = "The one true label."
          new_example = {
              "text": "A bunch of new words that are not in the other task, "
              "which the model should be able to use to identify "
              "this label.",
              "labels": [ANS],
              "episode_done": True,
          }
          agent.observe(new_example)
          reply = agent.act()
          assert "text" in reply and reply["text"] == ANS
  
          new_example.pop("labels")
          agent.observe(new_example)
          reply = agent.act()
          assert reply["text"] == ANS
  
file_path: ParlAI/tests/test_tfidf_retriever.py
imports: from parlai.core.agents import create_agent_from_model_file
  import parlai.utils.testing
  import os
  import unittest
label_desc: Use image node_id 1 for calling the TestTfidfRetriever obj's underlying member method code with example usage: obj.test_sparse_tfidf_multiworkers() without return types