def test_1(): it = PeekingIterator(Iterator([1, 2, 3, 4])) res = [] while it.hasNext(): res.append(it.peek()) res.append(it.next()) assert res == [1, 1, 2, 2, 3, 3, 4, 4]
def test_0(): it = PeekingIterator(Iterator([])) assert not it.hasNext()