Detect if a reader is ready to be read from

is_reader_ready.rs

async fn is_reader_ready<R>(reader: &mut R) -> bool where R: AsyncRead + Unpin {
    let mut me = &mut *reader;

    poll_fn(|cx| {
        let mut v = [];
        Poll::Ready(Pin::new(&mut me).poll_read(cx, &mut v[..]).is_ready())
    }).await
}

Don't actually use this. I originally wrote it for testing purposes before realising

1. it tests implementation details
2. reading into a 0 sized buffer is not always going to do what you expect it to. Some futures might even shortcut this and say they are always ready to read because they kind of are, you asked them for no data they can definitely serve you that lol
3. Majority of futures make no guarantee how many times you will need to poll them before they are actually ready. So even if you're testing your own future, if it calls other futures you have no guarantee this will return what you expect