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use futures::io::AsyncRead;
use futures_test::task::panic_context;
use std::io;
use std::pin::Pin;
use std::task::{Context, Poll};
struct MockReader {
fun: Box<dyn FnMut(&mut [u8]) -> Poll<io::Result<usize>>>,
}
impl MockReader {
fn new(fun: impl FnMut(&mut [u8]) -> Poll<io::Result<usize>> + 'static) -> Self {
Self { fun: Box::new(fun) }
}
}
impl AsyncRead for MockReader {
fn poll_read(
self: Pin<&mut Self>,
_cx: &mut Context<'_>,
buf: &mut [u8],
) -> Poll<io::Result<usize>> {
(self.get_mut().fun)(buf)
}
}
/// Verifies that the default implementation of `poll_read_vectored`
/// calls `poll_read` with an empty slice if no buffers are provided.
#[test]
fn read_vectored_no_buffers() {
let mut reader = MockReader::new(|buf| {
assert_eq!(buf, b"");
Err(io::ErrorKind::BrokenPipe.into()).into()
});
let cx = &mut panic_context();
let bufs = &mut [];
let res = Pin::new(&mut reader).poll_read_vectored(cx, bufs);
let res = res.map_err(|e| e.kind());
assert_eq!(res, Poll::Ready(Err(io::ErrorKind::BrokenPipe)))
}
/// Verifies that the default implementation of `poll_read_vectored`
/// calls `poll_read` with the first non-empty buffer.
#[test]
fn read_vectored_first_non_empty() {
let mut reader = MockReader::new(|buf| {
assert_eq!(buf.len(), 4);
buf.copy_from_slice(b"four");
Poll::Ready(Ok(4))
});
let cx = &mut panic_context();
let mut buf = [0; 4];
let bufs = &mut [
io::IoSliceMut::new(&mut []),
io::IoSliceMut::new(&mut []),
io::IoSliceMut::new(&mut buf),
];
let res = Pin::new(&mut reader).poll_read_vectored(cx, bufs);
let res = res.map_err(|e| e.kind());
assert_eq!(res, Poll::Ready(Ok(4)));
assert_eq!(buf, b"four"[..]);
}