code: def test_file_not_created(self, tmp):
      it = file_tail_iterator(tmp)
      assert next(it) is None
      f = open(tmp, "w")
      f.write("hi\n")
      f.flush()
      assert next(it) is not None
  
file_path: ray/python/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 2 for calling the TestIterLine obj's underlying member method code with example usage: obj.test_file_not_created(tmp) without return types