code: def test_timezone_info(self):
      # see gh-11682: Timezone info lost when broadcasting
      # scalar datetime to DataFrame
  
      df = DataFrame({"a": [1], "b": [datetime.now(pytz.utc)]})
      assert df["b"][0].tzinfo == pytz.utc
      df = DataFrame({"a": [1, 2, 3]})
      df["b"] = datetime.now(pytz.utc)
      assert df["b"][0].tzinfo == pytz.utc
  
imports: from datetime import datetime, timedelta
  import numpy
  import pytest
  import pytz
  import pandas
  from pandas import DataFrame, DatetimeIndex, Index, MultiIndex, Series, Timestamp, date_range, offsets
  import pandas._testing
  from pandas.core.groupby.grouper import Grouper
  from pandas.core.groupby.ops import BinGrouper
label_desc: Use image node_id 18 for calling the TestGroupBy obj's underlying member method code with example usage: obj.test_timezone_info() without return types