def test_clear(self):
dll = LinkedList()
items = 100
assert dll.is_empty()
for i in range(items):
assert dll.append(i) is None
assert isinstance(dll.head, Node)
assert isinstance(dll.tail, Node)
assert dll.size == items
assert dll.clear() is None
assert dll.head is None
assert dll.tail is None
assert dll.size == 0
def test_clear_empty(self):
dll = LinkedList()
assert dll.is_empty()
assert dll.clear() is None
assert dll.is_empty()