io_read_exact.rs - mozsearch

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use futures::executor::block_on;

use futures::io::AsyncReadExt;

#[test]

fn read_exact() {

    let mut reader: &[u8] = &[1, 2, 3, 4, 5];

    let mut out = [0u8; 3];

    let res = block_on(reader.read_exact(&mut out)); // read 3 bytes out

    assert!(res.is_ok());

    assert_eq!(out, [1, 2, 3]);

    assert_eq!(reader.len(), 2);

    let res = block_on(reader.read_exact(&mut out)); // read another 3 bytes, but only 2 bytes left

    assert!(res.is_err());

    assert_eq!(reader.len(), 0);