futures-channel 0.2.1

extern crate futures;
extern crate futures_channel;
extern crate futures_executor;

use std::sync::atomic::*;
use std::thread;

use futures::prelude::*;
use futures::future::{result, poll_fn};
use futures_executor::block_on;
use futures_channel::mpsc;

#[test]
fn sequence() {
    let (tx, rx) = mpsc::channel(1);

    let amt = 20;
    let t = thread::spawn(move || {
        block_on(send(amt, tx)).unwrap()
    });
    let list: Vec<_> = block_on(rx.collect()).unwrap();
    let mut list = list.into_iter();
    for i in (1..amt + 1).rev() {
        assert_eq!(list.next(), Some(i));
    }
    assert_eq!(list.next(), None);

    t.join().unwrap();

    fn send(n: u32, sender: mpsc::Sender<u32>)
            -> Box<Future<Item=(), Error=()> + Send> {
        if n == 0 {
            return Box::new(result(Ok(())))
        }
        Box::new(sender.send(n).map_err(|_| ()).and_then(move |sender| {
            send(n - 1, sender)
        }))
    }
}

#[test]
fn drop_sender() {
    let (tx, mut rx) = mpsc::channel::<u32>(1);
    drop(tx);
    let f = poll_fn(|cx| {
        rx.poll_next(cx)
    });
    assert_eq!(block_on(f).unwrap(), None)
}

#[test]
fn drop_rx() {
    let (tx, rx) = mpsc::channel::<u32>(1);
    let tx = block_on(tx.send(1)).unwrap();
    drop(rx);
    assert!(block_on(tx.send(1)).is_err());
}

#[test]
fn drop_order() {
    static DROPS: AtomicUsize = ATOMIC_USIZE_INIT;
    let (tx, rx) = mpsc::channel(1);

    struct A;

    impl Drop for A {
        fn drop(&mut self) {
            DROPS.fetch_add(1, Ordering::SeqCst);
        }
    }

    let tx = block_on(tx.send(A)).unwrap();
    assert_eq!(DROPS.load(Ordering::SeqCst), 0);
    drop(rx);
    assert_eq!(DROPS.load(Ordering::SeqCst), 1);
    assert!(block_on(tx.send(A)).is_err());
    assert_eq!(DROPS.load(Ordering::SeqCst), 2);
}