def test_should_not_be_able_to_remove_non_existing(self):
rrs = RoundRobinSet([1, 2, 3])
with self.assertRaises(ValueError):
rrs.remove(4)
def test_should_be_able_to_remove_existing(self):
rrs = RoundRobinSet([1, 2, 3])
rrs.remove(2)
assert list(rrs) == [1, 3]