code: def test_join_nonunique(self):
      idx1 = to_datetime(
          ["2012-11-06 16:00:11.477563", "2012-11-06 16:00:11.477563"]
      )
      idx2 = to_datetime(
          ["2012-11-06 15:11:09.006507", "2012-11-06 15:11:09.006507"]
      )
      rs = idx1.join(idx2, how="outer")
      assert rs.is_monotonic_increasing
  
file_path: pandas/pandas/tests/indexes/datetimes/test_join.py
imports: from datetime import datetime, timezone
  import numpy
  import pytest
  from pandas import DataFrame, DatetimeIndex, Index, Timestamp, date_range, period_range, to_datetime
  import pandas._testing
  from pandas.tseries.offsets import BDay, BMonthEnd
label_desc: Use image node_id 7 for calling the TestJoin obj's underlying member method code with example usage: obj.test_join_nonunique() without return types