def test_normal_iterator_if_not_told_to_step_back(self):
input_list = [0, 1, 2, 3, 4, 5]
iterator = bidirectional_iterator.BidirectionalIterator(input_list)
results = []
for index in iterator:
results.append(index)
assert results == input_list
def test_cannot_step_back_too_far_after_stepping_in(self):
iterator = bidirectional_iterator.BidirectionalIterator([0, 1, 2])
for _ in range(3):
iterator.__next__()
for _ in range(2):
iterator.step_back_on_next_iteration()
iterator.__next__()
iterator.step_back_on_next_iteration()
with pytest.raises(StopIteration):
iterator.__next__()
def test_works_correctly_in_loop(self):
iterator = bidirectional_iterator.BidirectionalIterator(
[0, 1, 2, 3, 4, 5])
commands = [0, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0]
command_count = 0
results = []
for index in iterator:
if commands[command_count]:
iterator.step_back_on_next_iteration()
results.append(index)
command_count += 1
assert results == [0, 1, 0, 1, 2, 1, 0, 1, 2, 3, 4, 3, 2, 3, 4, 5]
def test_knows_when_stepping_back_possible(self):
iterator = bidirectional_iterator.BidirectionalIterator([0, 1, 2, 3])
commands = [0, 1, 0, 0, 1, 1, 0, 0, 0, 0]
command_count = 0
results = []
for _ in iterator:
if commands[command_count]:
iterator.step_back_on_next_iteration()
results.append(iterator.can_step_back())
command_count += 1
assert results == [
False, True, False, True, True, True, False, True, True, True
]
def test_no_input(self):
iterator = bidirectional_iterator.BidirectionalIterator([])
with pytest.raises(StopIteration):
iterator.__next__()
def test_cannot_step_back_too_far(self):
iterator = bidirectional_iterator.BidirectionalIterator([0])
iterator.step_back_on_next_iteration()
with pytest.raises(StopIteration):
iterator.__next__()
