code: def test_at_time_midnight(self, frame_or_series):
      # midnight, everything
      rng = date_range("1/1/2000", "1/31/2000")
      ts = DataFrame(
          np.random.default_rng(2).standard_normal((len(rng), 3)),
          index=rng,
      )
      ts = tm.get_obj(ts, frame_or_series)
  
      result = ts.at_time(time(0, 0))
      tm.assert_equal(result, ts)
  
file_path: pandas/pandas/tests/frame/methods/test_at_time.py
imports: from datetime import time
  import numpy
  import pytest
  import pytz
  from pandas._libs.tslibs import timezones
  from pandas import DataFrame, date_range
  import pandas._testing
label_desc: Use image node_id 3 for calling the TestAtTime obj's underlying member method code with example usage: obj.test_at_time_midnight(frame_or_series) without return types