@XFAIL
def test_union_boundary_of_joining_sets():
    assert Union(Interval(0, 10), Interval(10, 15), evaluate=False).boundary \
            == FiniteSet(0, 15)
Testing the boundary of unions is a hard problem
dataset/ETHPy150Open sympy/sympy/sympy/sets/tests/test_sets.py/test_union_boundary_of_joining_sets