public void TestIntersectWithEdgeCase()
{
EqualityComparer <int> equalityComparer = EqualityComparer <int> .Default;
Func <int, int> getHashCode = value => Math.Abs(value) < 5 ? 0 : 1;
ImmutableTreeSet <int> .Builder set = ImmutableTreeSet.CreateBuilder(new SubsetHashCodeEqualityComparer <int>(equalityComparer, getHashCode));
ImmutableTreeSet <int> .Builder other = ImmutableTreeSet.CreateBuilder(set.KeyComparer);
set.UnionWith(Enumerable.Range(0, 10));
other.UnionWith(new[] { 4, 3, 5 });
set.IntersectWith(other);
Assert.Equal(new[] { 3, 4, 5 }, set);
}