code: def test_union_empty_result(self, closed, sort):
      # GH 19101: empty result, same dtype
      index = empty_index(dtype="int64", closed=closed)
      result = index.union(index, sort=sort)
      tm.assert_index_equal(result, index)
  
      # GH 19101: empty result, different numeric dtypes -> common dtype is f8
      other = empty_index(dtype="float64", closed=closed)
      result = index.union(other, sort=sort)
      expected = other
      tm.assert_index_equal(result, expected)
  
      other = index.union(index, sort=sort)
      tm.assert_index_equal(result, expected)
  
      other = empty_index(dtype="uint64", closed=closed)
      result = index.union(other, sort=sort)
      tm.assert_index_equal(result, expected)
  
      result = other.union(index, sort=sort)
      tm.assert_index_equal(result, expected)
  
file_path: pandas/pandas/tests/indexes/interval/test_setops.py
imports: import numpy
  import pytest
  from pandas import Index, IntervalIndex, Timestamp, interval_range
  import pandas._testing
label_desc: Use image node_id 2 for calling the TestIntervalIndex obj's underlying member method code with example usage: obj.test_union_empty_result(closed, sort) without return types