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use core::iter::*;
#[test]
fn test_iterator_skip_while() {
let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19];
let ys = [15, 16, 17, 19];
let it = xs.iter().skip_while(|&x| *x < 15);
let mut i = 0;
for x in it {
assert_eq!(*x, ys[i]);
i += 1;
}
assert_eq!(i, ys.len());
}
#[test]
fn test_iterator_skip_while_fold() {
let xs = [0, 1, 2, 3, 5, 13, 15, 16, 17, 19];
let ys = [15, 16, 17, 19];
let it = xs.iter().skip_while(|&x| *x < 15);
let i = it.fold(0, |i, &x| {
assert_eq!(x, ys[i]);
i + 1
});
assert_eq!(i, ys.len());
let mut it = xs.iter().skip_while(|&x| *x < 15);
assert_eq!(it.next(), Some(&ys[0])); // process skips before folding
let i = it.fold(1, |i, &x| {
assert_eq!(x, ys[i]);
i + 1
});
assert_eq!(i, ys.len());
}
#[test]
fn test_skip_while_try_fold() {
let f = &|acc, x| i32::checked_add(2 * acc, x);
fn p(&x: &i32) -> bool {
(x % 10) <= 5
}
assert_eq!((1..20).skip_while(p).try_fold(7, f), (6..20).try_fold(7, f));
let mut iter = (1..20).skip_while(p);
assert_eq!(iter.nth(5), Some(11));
assert_eq!(iter.try_fold(7, f), (12..20).try_fold(7, f));
let mut iter = (0..50).skip_while(|&x| (x % 20) < 15);
assert_eq!(iter.try_fold(0, i8::checked_add), None);
assert_eq!(iter.next(), Some(23));
}
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