def test_can_insert_before_first():
tester = LinkedList()
tester.insert(4)
tester.insert(3)
tester.insert(2)
tester.insert(1)
tester.insert_before(1, "Before first")
assert tester
def test_can_insert_before_middle():
tester = LinkedList()
tester.insert(4)
tester.insert(3)
tester.insert(2)
tester.insert(1)
tester.insert_before(3, "Middle")
assert tester
def test_insert_before_first():
lst = LinkedList()
lst.insert("{c}")
lst.insert("{b}")
lst.insert("{a}")
lst.insert_before("{a}", "{d}")
actual = lst.__str__()
expected = "{d} -> {a} -> {b} -> {c} -> None"
assert actual == expected
def test_insert_before():
ll = LinkedList()
ll.append_node(1)
ll.append_node(2)
ll.append_node(3)
ll.append_node(4)
ll.append_node(5)
ll.insert_before(3, 2.5)
actual = ll.return_all()
expected = [1, 2, 2.5, 3, 4, 5]
assert actual == expected
