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_buf_writer.rs
    path of file: ./repos/tokio/tokio/tests
    
    the code of the file until where you have to start completion: #![warn(rust_2018_idioms)]
#![cfg(feature = "full")]

// https://github.com/rust-lang/futures-rs/blob/1803948ff091b4eabf7f3bf39e16bbbdefca5cc8/futures/tests/io_buf_wri
    
async fn write_vectored_large_slice_on_non_vectored() {
    let msg = b"foo bar baz";
    let mut bufs = [
        IoSlice::new(&[]),
        IoSlice::new(&msg[..9]),
        IoSlice::new(&msg[9..]),
    ];
    let mut h = VectoredWriteHarness::new(8);
    let bytes_written = h.write_all(IoBufs::new(&mut bufs)).await;
    assert_eq!(bytes_written, msg.len());
    assert_eq!(h.flush().await, msg);
}