From e80a37558df5ac9828caccd48459fdb7be488f5b Mon Sep 17 00:00:00 2001 From: Andrea Corradi Date: Thu, 2 May 2019 14:35:43 +0000 Subject: Add custom nth_back for Skip --- src/libcore/tests/iter.rs | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) (limited to 'src/libcore/tests') diff --git a/src/libcore/tests/iter.rs b/src/libcore/tests/iter.rs index 7dfb1adad9e..7e3190f8a20 100644 --- a/src/libcore/tests/iter.rs +++ b/src/libcore/tests/iter.rs @@ -2280,6 +2280,40 @@ fn test_skip_try_folds() { assert_eq!(iter.next_back(), Some(24)); } +#[test] +fn test_skip_nth_back() { + let xs = [0, 1, 2, 3, 4, 5]; + let mut it = xs.iter().skip(2); + assert_eq!(it.nth_back(0), Some(&5)); + assert_eq!(it.nth_back(1), Some(&3)); + assert_eq!(it.nth_back(0), Some(&2)); + assert_eq!(it.nth_back(0), None); + + let ys = [2, 3, 4, 5]; + let mut ity = ys.iter(); + let mut it = xs.iter().skip(2); + assert_eq!(it.nth_back(1), ity.nth_back(1)); + assert_eq!(it.clone().nth(0), ity.clone().nth(0)); + assert_eq!(it.nth_back(0), ity.nth_back(0)); + assert_eq!(it.clone().nth(0), ity.clone().nth(0)); + assert_eq!(it.nth_back(0), ity.nth_back(0)); + assert_eq!(it.clone().nth(0), ity.clone().nth(0)); + assert_eq!(it.nth_back(0), ity.nth_back(0)); + assert_eq!(it.clone().nth(0), ity.clone().nth(0)); + + let mut it = xs.iter().skip(2); + assert_eq!(it.nth_back(4), None); + assert_eq!(it.nth_back(0), None); + + let mut it = xs.iter(); + it.by_ref().skip(2).nth_back(3); + assert_eq!(it.next_back(), Some(&1)); + + let mut it = xs.iter(); + it.by_ref().skip(2).nth_back(10); + assert_eq!(it.next_back(), Some(&1)); +} + #[test] fn test_take_try_folds() { let f = &|acc, x| i32::checked_add(2*acc, x); -- cgit 1.4.1-3-g733a5