def test_insert_before_reference_does_not_exist():
ll = LinkedList()
with pytest.raises(Exception) as context:
ll.insert(1)
ll.insert_before(3, 5)
assert str(context.value) == 'No node containing: 5'
def test_insert_before_exists():
ll = LinkedList()
ll.insert(3)
ll.insert(1)
ll.insert_before(2, 3)
assert str(ll) == '{ 1 } -> { 2 } -> { 3 } -> NULL'
def test_insert_before_empty():
ll = LinkedList()
with pytest.raises(Exception) as context:
ll.insert_before(3, 5)
assert str(context.value) == "Cannot `insert_before` on empty LinkedList"