public void TestExceptWith() { var a = new RedBlackSetTester<int>(_numbers); Assert.That(() => a.ExceptWith(null), Throws.InstanceOf<ArgumentNullException>()); a.ExceptWith(_odd); Assert.That(a, Is.EqualTo(_even.Where(x => x <= _numbers.Max()))); a.ExceptWith(_primes); Assert.That(a, Is.EqualTo(_even.Where(x => x > 2 && x <= _numbers.Max()))); }