docstr: Test that train.py successfully completes one step
code: def test_end_to_end(self):
      """Test that train.py successfully completes one step"""
      output_dir = os.path.join("/tmp", str(uuid.uuid4()))
      os.makedirs(output_dir, exist_ok=True)
  
      subprocess.run(
          f"python -m domainbed.scripts.train --dataset RotatedMNIST "
          f'--data_dir={os.environ["DATA_DIR"]} --output_dir={output_dir} '
          f"--steps=501",
          shell=True,
      )
  
      with open(os.path.join(output_dir, "results.jsonl")) as f:
          lines = [l[:-1] for l in f]
          last_epoch = json.loads(lines[-1])
          self.assertEqual(last_epoch["step"], 500)
          # Conservative values; anything lower and something's likely wrong.
          self.assertGreater(last_epoch["env0_in_acc"], 0.80)
          self.assertGreater(last_epoch["env1_in_acc"], 0.95)
          self.assertGreater(last_epoch["env2_in_acc"], 0.95)
          self.assertGreater(last_epoch["env3_in_acc"], 0.95)
          self.assertGreater(last_epoch["env3_in_acc"], 0.95)
  
      with open(os.path.join(output_dir, "out.txt")) as f:
          text = f.read()
          self.assertTrue("500" in text)
  
file_path: generalized-moe/domainbed/test/scripts/test_train.py
imports: import json
  import os
  import subprocess
  import unittest
  import uuid
  import torch
label_desc: Use image node_id 1 for calling the TestTrain obj's underlying member method code with example usage: obj.test_end_to_end() without return types