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|
use super::*;
use core::iter::*;
#[test]
fn test_repeat() {
let mut it = repeat(42);
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), Some(42));
assert_eq!(repeat(42).size_hint(), (usize::MAX, None));
}
#[test]
fn test_repeat_take() {
let mut it = repeat(42).take(3);
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), None);
is_trusted_len(repeat(42).take(3));
assert_eq!(repeat(42).take(3).size_hint(), (3, Some(3)));
assert_eq!(repeat(42).take(0).size_hint(), (0, Some(0)));
assert_eq!(repeat(42).take(usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX)));
}
#[test]
fn test_repeat_take_collect() {
let v: Vec<_> = repeat(42).take(3).collect();
assert_eq!(v, vec![42, 42, 42]);
}
#[test]
fn test_repeat_with() {
#[derive(PartialEq, Debug)]
struct NotClone(usize);
let mut it = repeat_with(|| NotClone(42));
assert_eq!(it.next(), Some(NotClone(42)));
assert_eq!(it.next(), Some(NotClone(42)));
assert_eq!(it.next(), Some(NotClone(42)));
assert_eq!(repeat_with(|| NotClone(42)).size_hint(), (usize::MAX, None));
}
#[test]
fn test_repeat_with_take() {
let mut it = repeat_with(|| 42).take(3);
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), None);
is_trusted_len(repeat_with(|| 42).take(3));
assert_eq!(repeat_with(|| 42).take(3).size_hint(), (3, Some(3)));
assert_eq!(repeat_with(|| 42).take(0).size_hint(), (0, Some(0)));
assert_eq!(repeat_with(|| 42).take(usize::MAX).size_hint(), (usize::MAX, Some(usize::MAX)));
}
#[test]
fn test_repeat_with_take_collect() {
let mut curr = 1;
let v: Vec<_> = repeat_with(|| {
let tmp = curr;
curr *= 2;
tmp
})
.take(5)
.collect();
assert_eq!(v, vec![1, 2, 4, 8, 16]);
}
#[test]
fn test_successors() {
let mut powers_of_10 = successors(Some(1_u16), |n| n.checked_mul(10));
assert_eq!(powers_of_10.by_ref().collect::<Vec<_>>(), &[1, 10, 100, 1_000, 10_000]);
assert_eq!(powers_of_10.next(), None);
let mut empty = successors(None::<u32>, |_| unimplemented!());
assert_eq!(empty.next(), None);
assert_eq!(empty.next(), None);
}
#[test]
fn test_once() {
let mut it = once(42);
assert_eq!(it.next(), Some(42));
assert_eq!(it.next(), None);
}
#[test]
fn test_once_with() {
let count = Cell::new(0);
let mut it = once_with(|| {
count.set(count.get() + 1);
42
});
assert_eq!(count.get(), 0);
assert_eq!(it.next(), Some(42));
assert_eq!(count.get(), 1);
assert_eq!(it.next(), None);
assert_eq!(count.get(), 1);
assert_eq!(it.next(), None);
assert_eq!(count.get(), 1);
}
#[test]
fn test_empty() {
let mut it = empty::<i32>();
assert_eq!(it.next(), None);
}
#[test]
fn test_repeat_n_drop() {
#[derive(Clone, Debug)]
struct DropCounter<'a>(&'a Cell<usize>);
impl Drop for DropCounter<'_> {
fn drop(&mut self) {
self.0.set(self.0.get() + 1);
}
}
// `repeat_n(x, 0)` drops `x` immediately
let count = Cell::new(0);
let item = DropCounter(&count);
let mut it = repeat_n(item, 0);
assert_eq!(count.get(), 1);
assert!(it.next().is_none());
assert_eq!(count.get(), 1);
drop(it);
assert_eq!(count.get(), 1);
// Dropping the iterator needs to drop the item if it's non-empty
let count = Cell::new(0);
let item = DropCounter(&count);
let it = repeat_n(item, 3);
assert_eq!(count.get(), 0);
drop(it);
assert_eq!(count.get(), 1);
// Dropping the iterator doesn't drop the item if it was exhausted
let count = Cell::new(0);
let item = DropCounter(&count);
let mut it = repeat_n(item, 3);
assert_eq!(count.get(), 0);
let x0 = it.next().unwrap();
assert_eq!(count.get(), 0);
let x1 = it.next().unwrap();
assert_eq!(count.get(), 0);
let x2 = it.next().unwrap();
assert_eq!(count.get(), 0);
assert!(it.next().is_none());
assert_eq!(count.get(), 0);
assert!(it.next().is_none());
assert_eq!(count.get(), 0);
drop(it);
assert_eq!(count.get(), 0);
drop((x0, x1, x2));
assert_eq!(count.get(), 3);
}
|
