docstr: Test perplexities of reduced-bias models in the zoo.
docstr_tok: ["Test","perplexities","of","reduced-bias","models","in","the","zoo","."]
code: def test_perplexities(self):
      """
      Test perplexities of reduced-bias models in the zoo.
      """
      test_cases = [
          ("gender__name_scrambling", "transformer/generator", 22.91),
          (
              "gender__ctrl_gen_tokens",
              "projects.dialogue_bias.agents:NoBiasStyleGenAgent",
              22.61,
          ),
          (
              "gender__unlikelihood_sequence_level",
              "transformer/generator",
              11.44,
          ),
          (
              "gender_ethnicity__name_scrambling",
              "transformer/generator",
              19.57,
          ),
      ]
      # Perplexities are high because models were tuned on conversations starting with
      # "Hi! My name is ___."
      for model_name, model, desired_ppl in test_cases:
          _, test = testing_utils.eval_model(
              opt={
                  "batchsize": 4,
                  "beam_block_full_context": True,
                  "fp16": True,
                  "num_examples": 16,
                  "model": model,
                  "model_file": f"zoo:dialogue_bias/{model_name}/model",
                  "skip_generation": True,
                  "task": "blended_skill_talk",
              },
              skip_valid=True,
          )
          self.assertAlmostEqual(test["ppl"], desired_ppl, delta=0.05)
  
imports: import unittest
  import parlai.utils.testing
  from parlai.core.opt import Opt
label_desc: Use image node_id 1 for calling the TestDialogueBias obj's underlying member method code with example usage: obj.test_perplexities() without return types