code: def test_frame_join_tzaware(self):
      test1 = DataFrame(
          np.zeros((6, 3)),
          index=date_range(
              "2012-11-15 00:00:00",
              periods=6,
              freq="100ms",
              tz="US/Central",
          ),
      )
      test2 = DataFrame(
          np.zeros((3, 3)),
          index=date_range(
              "2012-11-15 00:00:00",
              periods=3,
              freq="250ms",
              tz="US/Central",
          ),
          columns=range(3, 6),
      )
  
      result = test1.join(test2, how="outer")
      expected = test1.index.union(test2.index)
  
      tm.assert_index_equal(result.index, expected)
      assert result.index.tz.zone == "US/Central"
  
imports: from datetime import datetime
  import numpy
  import pytest
  from pandas.errors import MergeError
  import pandas
  from pandas import DataFrame, Index, MultiIndex, date_range, period_range
  import pandas._testing
  from pandas.core.reshape.concat import concat
label_desc: Use image node_id 7 for calling the TestDataFrameJoin obj's underlying member method code with example usage: obj.test_frame_join_tzaware() without return types