3 //! You're probably viewing this file because you're adding a test (or you might
4 //! just be browsing, in that case, hey there!).
6 //! If you've made a test that happens to use one of DoubleEnded's methods, but
7 //! it tests another adapter or trait, you should *add it to the adapter or
8 //! trait's test file*.
10 //! Some examples would be `adapters::cloned::test_cloned_try_folds` or
11 //! `adapters::flat_map::test_double_ended_flat_map`, which use `try_fold` and
12 //! `next_back`, but test their own adapter.
15 fn test_iterator_rev_nth_back() {
16 let v: &[_] = &[0, 1, 2, 3, 4];
18 assert_eq!(v.iter().rev().nth_back(i).unwrap(), &v[i]);
20 assert_eq!(v.iter().rev().nth_back(v.len()), None);
24 fn test_iterator_rev_nth() {
25 let v: &[_] = &[0, 1, 2, 3, 4];
27 assert_eq!(v.iter().rev().nth(i).unwrap(), &v[v.len() - 1 - i]);
29 assert_eq!(v.iter().rev().nth(v.len()), None);
34 let xs = [2, 4, 6, 8, 10, 12, 14, 16];
35 let mut it = xs.iter();
38 assert!(it.rev().cloned().collect::<Vec<isize>>() == vec![16, 14, 12, 10, 8, 6]);
42 fn test_rev_try_folds() {
43 let f = &|acc, x| i32::checked_add(2 * acc, x);
44 assert_eq!((1..10).rev().try_fold(7, f), (1..10).try_rfold(7, f));
45 assert_eq!((1..10).rev().try_rfold(7, f), (1..10).try_fold(7, f));
47 let a = [10, 20, 30, 40, 100, 60, 70, 80, 90];
48 let mut iter = a.iter().rev();
49 assert_eq!(iter.try_fold(0_i8, |acc, &x| acc.checked_add(x)), None);
50 assert_eq!(iter.next(), Some(&70));
51 let mut iter = a.iter().rev();
52 assert_eq!(iter.try_rfold(0_i8, |acc, &x| acc.checked_add(x)), None);
53 assert_eq!(iter.next_back(), Some(&60));
58 fn f(xy: &(isize, char)) -> bool {
62 fn g(xy: &(isize, char)) -> bool {
66 let v = [(0, 'a'), (1, 'b'), (2, 'c'), (3, 'b')];
68 assert_eq!(v.iter().rposition(f), Some(3));
69 assert!(v.iter().rposition(g).is_none());
73 fn test_rev_rposition() {
75 assert_eq!(v.iter().rev().rposition(|&x| x == 1), Some(1));
80 fn test_rposition_panic() {
81 let u = (Box::new(0), Box::new(0));
82 let v: [(Box<_>, Box<_>); 4] = [u.clone(), u.clone(), u.clone(), u];
84 v.iter().rposition(|_elt| {