use tokio_stream::{self as stream, Stream, StreamExt}; use tokio_test::task; use tokio_test::{assert_pending, assert_ready}; mod support { pub(crate) mod mpsc; } use support::mpsc; #[tokio::test] async fn merge_sync_streams() { let mut s = stream::iter(vec![0, 2, 4, 6]).merge(stream::iter(vec![1, 3, 5])); for i in 0..7 { let rem = 7 - i; assert_eq!(s.size_hint(), (rem, Some(rem))); assert_eq!(Some(i), s.next().await); } assert!(s.next().await.is_none()); } #[tokio::test] async fn merge_async_streams() { let (tx1, rx1) = mpsc::unbounded_channel_stream(); let (tx2, rx2) = mpsc::unbounded_channel_stream(); let mut rx = task::spawn(rx1.merge(rx2)); assert_eq!(rx.size_hint(), (0, None)); assert_pending!(rx.poll_next()); tx1.send(1).unwrap(); assert!(rx.is_woken()); assert_eq!(Some(1), assert_ready!(rx.poll_next())); assert_pending!(rx.poll_next()); tx2.send(2).unwrap(); assert!(rx.is_woken()); assert_eq!(Some(2), assert_ready!(rx.poll_next())); assert_pending!(rx.poll_next()); drop(tx1); assert!(rx.is_woken()); assert_pending!(rx.poll_next()); tx2.send(3).unwrap(); assert!(rx.is_woken()); assert_eq!(Some(3), assert_ready!(rx.poll_next())); assert_pending!(rx.poll_next()); drop(tx2); assert!(rx.is_woken()); assert_eq!(None, assert_ready!(rx.poll_next())); } #[test] fn size_overflow() { struct Monster; impl tokio_stream::Stream for Monster { type Item = (); fn poll_next( self: std::pin::Pin<&mut Self>, _cx: &mut std::task::Context<'_>, ) -> std::task::Poll> { panic!() } fn size_hint(&self) -> (usize, Option) { (usize::max_value(), Some(usize::max_value())) } } let m1 = Monster; let m2 = Monster; let m = m1.merge(m2); assert_eq!(m.size_hint(), (usize::max_value(), None)); }