#![warn(rust_2018_idioms)] #![cfg(feature = "full")] use tokio::io::{AsyncWrite, AsyncWriteExt}; use tokio_test::assert_ok; use bytes::BytesMut; use std::cmp; use std::io; use std::pin::Pin; use std::task::{Context, Poll}; #[tokio::test] async fn write_all() { struct Wr { buf: BytesMut, cnt: usize, } impl AsyncWrite for Wr { fn poll_write( mut self: Pin<&mut Self>, _cx: &mut Context<'_>, buf: &[u8], ) -> Poll> { let n = cmp::min(4, buf.len()); let buf = &buf[0..n]; self.cnt += 1; self.buf.extend(buf); Ok(buf.len()).into() } fn poll_flush(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll> { Ok(()).into() } fn poll_shutdown(self: Pin<&mut Self>, _cx: &mut Context<'_>) -> Poll> { Ok(()).into() } } let mut wr = Wr { buf: BytesMut::with_capacity(64), cnt: 0, }; assert_ok!(wr.write_all(b"hello world").await); assert_eq!(wr.buf, b"hello world"[..]); assert_eq!(wr.cnt, 3); }