assert_eq!(it.nth_back(1), None);
}
+#[test]
+fn test_take_advance_by() {
+ let mut take = (0..10).take(3);
+ assert_eq!(take.advance_by(2), Ok(()));
+ assert_eq!(take.next(), Some(2));
+ assert_eq!(take.advance_by(1), Err(0));
+
+ assert_eq!((0..0).take(10).advance_by(0), Ok(()));
+ assert_eq!((0..0).take(10).advance_by(1), Err(0));
+ assert_eq!((0..10).take(4).advance_by(5), Err(4));
+
+ let mut take = (0..10).take(3);
+ assert_eq!(take.advance_back_by(2), Ok(()));
+ assert_eq!(take.next(), Some(0));
+ assert_eq!(take.advance_back_by(1), Err(0));
+
+ assert_eq!((0..2).take(1).advance_back_by(10), Err(1));
+ assert_eq!((0..0).take(1).advance_back_by(1), Err(0));
+ assert_eq!((0..0).take(1).advance_back_by(0), Ok(()));
+ assert_eq!((0..usize::MAX).take(100).advance_back_by(usize::MAX), Err(100));
+}
+
#[test]
fn test_iterator_take_short() {
let xs = [0, 1, 2, 3];