code: def test_delete_file(self):
      with NamedTemporaryFile() as tmp:
          it = file_tail_iterator(tmp.name)
          f = open(tmp.name, "w")
  
          assert next(it) is None
  
          f.write("hi\n")
          f.flush()
  
          assert next(it) == ["hi\n"]
  
      # Calls should continue returning None after file deleted.
      assert next(it) is None
  
file_path: ray/dashboard/modules/job/tests/test_utils.py
imports: from tempfile import NamedTemporaryFile
  import sys
  import pytest
  from ray.dashboard.modules.job.common import JobSubmitRequest
  from ray.dashboard.modules.job.utils import file_tail_iterator, strip_keys_with_value_none, parse_and_validate_request, redact_url_password
label_desc: Use image node_id 8 for calling the TestIterLine obj's underlying member method code with example usage: obj.test_delete_file() without return types