def main():
# Start with empty list
llist = DoublyLinkedList()
# Insert 6. So the list becomes 6->None
llist.append(6)
# Insert 7 at the beginning.
# So linked list becomes 7->6->None
llist.push(7)
# Insert 1 at the beginning.
# So linked list becomes 1->7->6->None
llist.push(1)
# Insert 4 at the end.
# So linked list becomes 1->7->6->4->None
llist.append(4)
# Insert 8, after 7.
# So linked list becomes 1->7->8->6->4->None
llist.insert(llist.head.next, 8)
print('###################')
llist.printList()
# So linked list becomes 1->7->8->2->6->4->None
llist.insertAt(2, 2)
llist.printList()
print('###################')
llist.delete(llist.head)
llist.delete(llist.head.next)
llist.delete(llist.head.next)
llist.printList()
print('###################')
llist.deleteAt(2)
llist.printList()
def test_delete(self):
"""
tests the delete(index) method
"""
dll = DoublyLinkedList()
# test out of bounds
self.assertIsNone(dll.delete(-1))
self.assertIsNone(dll.delete(1))
dll.push(0) # index 0
dll.push(1) # index 1
dll.push(2) # index 2
# test can delete head (index 0)
deleted = dll.delete(0)
self.assertIsInstance(deleted, Node)
self.assertEqual(deleted.data, 0)
self.assertEqual(dll.length, 2)
# unshift the node back, then test delete at tail (index 2)
dll.unshift(0)
self.assertEqual(dll.to_list(), [0, 1, 2])
self.assertEqual(dll.length, 3)
deleted = dll.delete(dll.length - 1) # index 2
self.assertIsInstance(deleted, Node)
self.assertEqual(deleted.data, 2)
self.assertEqual(dll.length, 2)
# push the node back, then test delete from middle (index 1)
dll.push(2)
self.assertEqual(dll.to_list(), [0, 1, 2])
self.assertEqual(dll.length, 3)
deleted = dll.delete(1)
self.assertIsInstance(deleted, Node)
self.assertEqual(deleted.data, 1)
self.assertEqual(dll.length, 2)
