tokio/tests/io_read.rs


1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38

#![warn(rust_2018_idioms)]
#![cfg(feature = "full")]

use tokio::io::{AsyncRead, AsyncReadExt, ReadBuf};
use tokio_test::assert_ok;

use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};

#[tokio::test]
async fn read() {
    #[derive(Default)]
    struct Rd {
        poll_cnt: usize,
    }

    impl AsyncRead for Rd {
        fn poll_read(
            mut self: Pin<&mut Self>,
            _cx: &mut Context<'_>,
            buf: &mut ReadBuf<'_>,
        ) -> Poll<io::Result<()>> {
            assert_eq!(0, self.poll_cnt);
            self.poll_cnt += 1;

            buf.put_slice(b"hello world");
            Poll::Ready(Ok(()))
        }
    }

    let mut buf = Box::new([0; 11]);
    let mut rd = Rd::default();

    let n = assert_ok!(rd.read(&mut buf[..]).await);
    assert_eq!(n, 11);
    assert_eq!(buf[..], b"hello world"[..]);
}