mpsc-size_hint.rs - mozsearch

Enable keyboard shortcuts

use futures::channel::mpsc;

use futures::stream::Stream;

#[test]

fn unbounded_size_hint() {

    let (tx, mut rx) = mpsc::unbounded::<u32>();

    assert_eq!((0, None), rx.size_hint());

    tx.unbounded_send(1).unwrap();

    assert_eq!((1, None), rx.size_hint());

    rx.try_next().unwrap().unwrap();

    assert_eq!((0, None), rx.size_hint());

    tx.unbounded_send(2).unwrap();

    tx.unbounded_send(3).unwrap();

    assert_eq!((2, None), rx.size_hint());

    drop(tx);

    assert_eq!((2, Some(2)), rx.size_hint());

    rx.try_next().unwrap().unwrap();

    assert_eq!((1, Some(1)), rx.size_hint());

    rx.try_next().unwrap().unwrap();

    assert_eq!((0, Some(0)), rx.size_hint());

#[test]

fn channel_size_hint() {

    let (mut tx, mut rx) = mpsc::channel::<u32>(10);

    assert_eq!((0, None), rx.size_hint());

    tx.try_send(1).unwrap();

    assert_eq!((1, None), rx.size_hint());

    rx.try_next().unwrap().unwrap();

    assert_eq!((0, None), rx.size_hint());

    tx.try_send(2).unwrap();

    tx.try_send(3).unwrap();

    assert_eq!((2, None), rx.size_hint());

    drop(tx);

    assert_eq!((2, Some(2)), rx.size_hint());

    rx.try_next().unwrap().unwrap();

    assert_eq!((1, Some(1)), rx.size_hint());

    rx.try_next().unwrap().unwrap();

    assert_eq!((0, Some(0)), rx.size_hint());