You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: io_stream_reader.rs
    path of file: ./repos/phaser/phaser/vendor/tokio-util/tests
    
    the code of the file until where you have to start completion: #![warn(rust_2018_idioms)]

use bytes::Bytes;
use tokio::io::AsyncReadExt;
use tokio_stream::iter;
use tokio_util::io::StreamReader;

#[tokio::test]
async fn test_stream_reader() -> std::io::Result<()> {
    let stream = iter(vec![
        std::io::Result::Ok(Bytes::from_static(&[])),
        Ok(Bytes::from_static(&[0, 1, 2, 3])),
        Ok(Bytes::from_static(&[])),
        Ok(Bytes::fro
    
async fn test_stream_reader() -> std::io::Result<()> {
    let stream = iter(vec![
        std::io::Result::Ok(Bytes::from_static(&[])),
        Ok(Bytes::from_static(&[0, 1, 2, 3])),
        Ok(Bytes::from_static(&[])),
        Ok(Bytes::from_static(&[4, 5, 6, 7])),
        Ok(Bytes::from_static(&[])),
        Ok(Bytes::from_static(&[8, 9, 10, 11])),
        Ok(Bytes::from_static(&[])),
    ]);

    let mut read = StreamReader::new(stream);

    let mut buf = [0; 5];
    read.read_exact(&mut buf).await?;
    assert_eq!(buf, [0, 1, 2, 3, 4]);

    assert_eq!(read.read(&mut buf).await?, 3);
    assert_eq!(&buf[..3], [5, 6, 7]);

    assert_eq!(read.read(&mut buf).await?, 4);
    assert_eq!(&buf[..4], [8, 9, 10, 11]);

    assert_eq!(read.read(&mut buf).await?, 0);

    Ok(())
}