1 files changed, 59 insertions, 0 deletions
diff --git a/third_party/rust/tokio/tests/io_read.rs b/third_party/rust/tokio/tests/io_read.rs
new file mode 100644
index 0000000000..cb1aa70523
--- /dev/null
+++ b/third_party/rust/tokio/tests/io_read.rs
@@ -0,0 +1,59 @@
+#![warn(rust_2018_idioms)]
+#![cfg(feature = "full")]
+
+use tokio::io::{AsyncRead, AsyncReadExt, ReadBuf};
+use tokio_test::assert_ok;
+
+use std::io;
+use std::pin::Pin;
+use std::task::{Context, Poll};
+
+#[tokio::test]
+async fn read() {
+    #[derive(Default)]
+    struct Rd {
+        poll_cnt: usize,
+    }
+
+    impl AsyncRead for Rd {
+        fn poll_read(
+            mut self: Pin<&mut Self>,
+            _cx: &mut Context<'_>,
+            buf: &mut ReadBuf<'_>,
+        ) -> Poll<io::Result<()>> {
+            assert_eq!(0, self.poll_cnt);
+            self.poll_cnt += 1;
+
+            buf.put_slice(b"hello world");
+            Poll::Ready(Ok(()))
+        }
+    }
+
+    let mut buf = Box::new([0; 11]);
+    let mut rd = Rd::default();
+
+    let n = assert_ok!(rd.read(&mut buf[..]).await);
+    assert_eq!(n, 11);
+    assert_eq!(buf[..], b"hello world"[..]);
+}
+
+struct BadAsyncRead;
+
+impl AsyncRead for BadAsyncRead {
+    fn poll_read(
+        self: Pin<&mut Self>,
+        _cx: &mut Context<'_>,
+        buf: &mut ReadBuf<'_>,
+    ) -> Poll<io::Result<()>> {
+        *buf = ReadBuf::new(Box::leak(vec![0; buf.capacity()].into_boxed_slice()));
+        buf.advance(buf.capacity());
+        Poll::Ready(Ok(()))
+    }
+}
+
+#[tokio::test]
+#[should_panic]
+async fn read_buf_bad_async_read() {
+    let mut buf = Vec::with_capacity(10);
+    BadAsyncRead.read_buf(&mut buf).await.unwrap();
+}