def test_pop_empty(self):
dll = LinkedList()
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
with pytest.raises(IndexError):
dll.pop()
def test_pop_out_of_range_negative(self):
dll = LinkedList()
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
assert dll.push(1) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.size == 1
with pytest.raises(IndexError):
dll.pop(-2)
def test_pop_2nd_negative(self):
dll = LinkedList()
items = 100
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
for i in range(items - 1, -1, -1):
assert dll.push(i) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.head.next, Node)
assert dll.head.prev is None
assert isinstance(dll.tail, Node)
assert isinstance(dll.tail.prev, Node)
assert dll.tail.next is None
assert dll.size == items
for j in range(items - 2, 0, -1):
second = dll.pop(-2)
assert isinstance(second, Node)
assert second.next is None
assert second.prev is None
assert second.data == j
assert isinstance(dll.head, Node)
assert isinstance(dll.head.next, Node)
assert dll.head.prev is None
assert isinstance(dll.tail, Node)
assert isinstance(dll.tail.prev, Node)
assert dll.tail.next is None
assert dll.head.data == 0
assert dll.tail.data == items - 1
assert dll.size == 2
def test_pop_tails_negative(self):
dll = LinkedList()
items = 100
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
for i in range(items - 1, -1, -1):
assert dll.push(i) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.head.next, Node)
assert dll.head.prev is None
assert isinstance(dll.tail, Node)
assert isinstance(dll.tail.prev, Node)
assert dll.tail.next is None
assert dll.size == items
for j in range(items - 1, -1, -1):
assert isinstance(dll.tail, Node)
tail = dll.pop(-1)
assert isinstance(tail, Node)
assert tail.data == j
assert tail.next == None
assert dll.size == items - (items - j)
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
def test_append_multiple(self):
dll = LinkedList()
items = 100
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
for i in range(items):
assert dll.append(i) is None
assert dll.size == i + 1
assert dll.tail.data == i
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is not dll.tail
assert dll.size == items
for j in range(items):
assert dll.pop().data == j
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
def test_pop_single_negative(self):
dll = LinkedList()
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
assert dll.push(1) is None
assert isinstance(dll.head, Node)
assert dll.head.next is None
assert dll.head.prev is None
assert isinstance(dll.tail, Node)
assert dll.tail.next is None
assert dll.tail.prev is None
assert dll.head.data == dll.tail.data
assert dll.size == 1
single = dll.pop(-1)
assert isinstance(single, Node)
assert single.data == 1
assert single.next is None
assert single.prev is None
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
def test_pop_heads(self):
dll = LinkedList()
items = 100
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
for i in range(items):
assert dll.push(i) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.head.next, Node)
assert dll.head.prev is None
assert isinstance(dll.tail, Node)
assert isinstance(dll.tail.prev, Node)
assert dll.tail.next is None
assert dll.size == items
for j in range(items - 1, -1, -1):
assert isinstance(dll.head, Node)
head = dll.pop()
assert isinstance(head, Node)
assert head.data == j
assert dll.size == items - (items - j)
assert dll.head is None
assert dll.tail is None
assert dll.size == 0