def test_remove_back():
list = DoubleLinkedList()
list.addFront('Last').addFront('First')
assert list.removeBack() == "Last"
assert list.front() == "First"
assert list.back() == "First"
assert list.removeBack() == "First"
assert list.isEmpty()
def test_copy():
list = DoubleLinkedList()
list.addFront(1).addFront(2).addFront(3)
copy = list.copy()
assert not copy == list
assert list.front() == 3
assert copy.front() == 3
assert copy.removeBack() == 1
assert copy.back() == 2
assert list.back() == 1
def test_multiple_elements():
list = DoubleLinkedList()
list.addFront(1).addBack(2)
assert list.front() == 1
assert list.back() == 2
def test_get_back_node():
list = DoubleLinkedList()
assert list.back() is None
list.addFront(1)
assert list.back() == 1
def test_add_element_to_back():
list = DoubleLinkedList()
list.addBack(1)
assert not list.isEmpty()
list.addBack(2).addBack(3)
assert list.back() == 3
def test_get_back_node():
list = DoubleLinkedList()
list.addFront("Second")
assert list.back() == "Second"
list.addFront("First")
assert list.back() == "Second"
def test_multiple_items_added_to_front():
list = DoubleLinkedList()
list.addFront('Last').addFront('First')
assert list.front() == 'First'
assert list.back() == 'Last'
