def test_union_int_categorical_with_nan():
ci = CategoricalIndex([1, 2, np.nan])
assert ci.categories.dtype.kind == "i"
idx = Index([1, 2])
result = idx.union(ci)
expected = Index([1, 2, np.nan], dtype=np.float64)
tm.assert_index_equal(result, expected)
result = ci.union(idx)
tm.assert_index_equal(result, expected)
