tests/io_read_to_string.rs

use futures::executor::block_on;
use futures::future::{Future, FutureExt};
use futures::io::{AsyncReadExt, Cursor};
use futures::stream::{self, StreamExt, TryStreamExt};
use futures::task::Poll;
use futures_test::io::AsyncReadTestExt;
use futures_test::task::noop_context;

#[test]
fn read_to_string() {
    let mut c = Cursor::new(&b""[..]);
    let mut v = String::new();
    assert_eq!(block_on(c.read_to_string(&mut v)).unwrap(), 0);
    assert_eq!(v, "");

    let mut c = Cursor::new(&b"1"[..]);
    let mut v = String::new();
    assert_eq!(block_on(c.read_to_string(&mut v)).unwrap(), 1);
    assert_eq!(v, "1");

    let mut c = Cursor::new(&b"\xff"[..]);
    let mut v = String::new();
    assert!(block_on(c.read_to_string(&mut v)).is_err());
}

#[test]
fn interleave_pending() {
    fn run<F: Future + Unpin>(mut f: F) -> F::Output {
        let mut cx = noop_context();
        loop {
            if let Poll::Ready(x) = f.poll_unpin(&mut cx) {
                return x;
            }
        }
    }
    let mut buf = stream::iter(vec![&b"12"[..], &b"33"[..], &b"3"[..]])
        .map(Ok)
        .into_async_read()
        .interleave_pending();

    let mut v = String::new();
    assert_eq!(run(buf.read_to_string(&mut v)).unwrap(), 5);
    assert_eq!(v, "12333");
}