io_read_to_string.rs

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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");