chore: checkpoint before Python removal

vendor/tokio-stream/tests/mpsc_bounded_stream.rs

@@ -0,0 +1,109 @@
+use futures::{Stream, StreamExt};
+use tokio::sync::mpsc;
+use tokio_stream::wrappers::ReceiverStream;
+
+#[tokio::test]
+async fn size_hint_stream_open() {
+    let (tx, rx) = mpsc::channel(4);
+
+    tx.send(1).await.unwrap();
+    tx.send(2).await.unwrap();
+
+    let mut stream = ReceiverStream::new(rx);
+
+    assert_eq!(stream.size_hint(), (2, None));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (1, None));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (0, None));
+}
+
+#[tokio::test]
+async fn size_hint_stream_closed() {
+    let (tx, rx) = mpsc::channel(4);
+
+    tx.send(1).await.unwrap();
+    tx.send(2).await.unwrap();
+
+    let mut stream = ReceiverStream::new(rx);
+    stream.close();
+
+    assert_eq!(stream.size_hint(), (2, Some(2)));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (1, Some(1)));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (0, Some(0)));
+}
+
+#[tokio::test]
+async fn size_hint_sender_dropped() {
+    let (tx, rx) = mpsc::channel(4);
+
+    tx.send(1).await.unwrap();
+    tx.send(2).await.unwrap();
+
+    let mut stream = ReceiverStream::new(rx);
+    drop(tx);
+
+    assert_eq!(stream.size_hint(), (2, Some(2)));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (1, Some(1)));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (0, Some(0)));
+}
+
+#[test]
+fn size_hint_stream_instantly_closed() {
+    let (_tx, rx) = mpsc::channel::<i32>(4);
+
+    let mut stream = ReceiverStream::new(rx);
+    stream.close();
+
+    assert_eq!(stream.size_hint(), (0, Some(0)));
+}
+
+#[tokio::test]
+async fn size_hint_stream_closed_permits_send() {
+    let (tx, rx) = mpsc::channel(4);
+
+    tx.send(1).await.unwrap();
+    let permit1 = tx.reserve().await.unwrap();
+    let permit2 = tx.reserve().await.unwrap();
+
+    let mut stream = ReceiverStream::new(rx);
+    stream.close();
+
+    assert_eq!(stream.size_hint(), (1, Some(3)));
+    permit1.send(2);
+    assert_eq!(stream.size_hint(), (2, Some(3)));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (1, Some(2)));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (0, Some(1)));
+    permit2.send(3);
+    assert_eq!(stream.size_hint(), (1, Some(1)));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (0, Some(0)));
+    assert_eq!(stream.next().await, None);
+}
+
+#[tokio::test]
+async fn size_hint_stream_closed_permits_drop() {
+    let (tx, rx) = mpsc::channel(4);
+
+    tx.send(1).await.unwrap();
+    let permit1 = tx.reserve().await.unwrap();
+    let permit2 = tx.reserve().await.unwrap();
+
+    let mut stream = ReceiverStream::new(rx);
+    stream.close();
+
+    assert_eq!(stream.size_hint(), (1, Some(3)));
+    drop(permit1);
+    assert_eq!(stream.size_hint(), (1, Some(2)));
+    stream.next().await;
+    assert_eq!(stream.size_hint(), (0, Some(1)));
+    drop(permit2);
+    assert_eq!(stream.size_hint(), (0, Some(0)));
+    assert_eq!(stream.next().await, None);
+}