def test_insert_empty(self):
dll = LinkedList()
assert dll.is_empty()
assert dll.insert(0, 0) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is dll.tail
assert dll.size == 1
def test_insert_new_tail(self):
dll = LinkedList()
assert dll.is_empty()
assert dll.push(1) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is dll.tail
assert dll.size == 1
assert dll.insert(1, 2) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is not dll.tail
assert dll.head.data == 1
assert dll.tail.data == 2
assert dll.head.next is dll.tail
assert dll.head.prev is None
assert dll.tail.prev is dll.head
assert dll.tail.next is None
assert dll.size == 2
def test_insert_new_head_negative_out_of_bounds(self):
dll = LinkedList()
assert dll.is_empty()
assert dll.push(1) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is dll.tail
assert dll.size == 1
assert dll.insert(-1000, 2) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is not dll.tail
assert dll.head.data == 2
assert dll.tail.data == 1
assert dll.head.next is dll.tail
assert dll.head.prev is None
assert dll.tail.prev is dll.head
assert dll.tail.next is None
assert dll.size == 2
def test_insert_new_tail_out_of_bounds(self):
dll = LinkedList()
assert dll.is_empty()
assert dll.push(0) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is dll.tail
assert dll.size == 1
assert dll.insert(1000, 1) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is not dll.tail
assert dll.head.data == 0
assert dll.tail.data == 1
assert dll.head.next is dll.tail
assert dll.head.next.data == 1
assert dll.head.prev is None
assert dll.tail.prev is dll.head
assert dll.tail.prev.data == 0
assert dll.tail.next is None
assert dll.size == 2
def test_insert_end_negative(self):
dll = LinkedList()
assert dll.is_empty()
assert dll.append(0) is None
assert dll.append(1) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is not dll.tail
assert dll.size == 2
assert dll.insert(-1, 2) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.head is not dll.tail
assert dll.head.data == 0
assert dll.tail.data == 1
assert dll.head.next is not dll.tail
assert dll.head.next.data == 2
assert dll.head.prev is None
assert dll.tail.prev is not dll.head
assert dll.tail.prev.data == 2
assert dll.tail.next is None
assert dll.size == 3