code: def setUpClass(cls):
      cls.model_id = "trl-internal-testing/dummy-GPT2-correct-vocab"
      cls.model = AutoModelForSequenceClassification.from_pretrained(
          cls.model_id
      )
      cls.tokenizer = AutoTokenizer.from_pretrained(cls.model_id)
      cls.tokenizer.pad_token = cls.tokenizer.eos_token
  
file_path: trl/tests/test_reward_trainer.py
imports: import tempfile
  import unittest
  import torch
  from datasets import Dataset
  from transformers import AutoModelForSequenceClassification, AutoTokenizer, EvalPrediction
  from trl import RewardConfig, RewardTrainer
  from trl.trainer import compute_accuracy
  from .testing_utils import require_peft
label_desc: Use image node_id 1 for calling the RewardTrainerTester obj's underlying member method code with example usage: obj.setUpClass(cls) without return types