chore: checkpoint before Python removal

vendor/tokio/tests/support/mpsc_stream.rs

@@ -0,0 +1,42 @@
+#![allow(dead_code)]
+
+use std::pin::Pin;
+use std::task::{Context, Poll};
+use tokio::sync::mpsc::{self, Receiver, Sender, UnboundedReceiver, UnboundedSender};
+use tokio_stream::Stream;
+
+struct UnboundedStream<T> {
+    recv: UnboundedReceiver<T>,
+}
+impl<T> Stream for UnboundedStream<T> {
+    type Item = T;
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> {
+        Pin::into_inner(self).recv.poll_recv(cx)
+    }
+}
+
+pub fn unbounded_channel_stream<T: Unpin>() -> (UnboundedSender<T>, impl Stream<Item = T>) {
+    let (tx, rx) = mpsc::unbounded_channel();
+
+    let stream = UnboundedStream { recv: rx };
+
+    (tx, stream)
+}
+
+struct BoundedStream<T> {
+    recv: Receiver<T>,
+}
+impl<T> Stream for BoundedStream<T> {
+    type Item = T;
+    fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll<Option<T>> {
+        Pin::into_inner(self).recv.poll_recv(cx)
+    }
+}
+
+pub fn channel_stream<T: Unpin>(size: usize) -> (Sender<T>, impl Stream<Item = T>) {
+    let (tx, rx) = mpsc::channel(size);
+
+    let stream = BoundedStream { recv: rx };
+
+    (tx, stream)
+}