stream: impl FromStream for BTreeSet (#7954)

tokio-stream/tests/stream_collect.rs

@@ -1,3 +1,5 @@
+use std::collections::BTreeSet;
+
 use tokio_stream::{self as stream, StreamExt};
 use tokio_test::{assert_pending, assert_ready, assert_ready_err, assert_ready_ok, task};
 
@@ -61,6 +63,27 @@ async fn collect_vec_items() {
     assert_eq!(vec![1, 2], coll);
 }
 
+#[tokio::test]
+async fn collect_btreeset_items() {
+    let (tx, rx) = mpsc::unbounded_channel_stream();
+    let mut fut = task::spawn(rx.collect::<BTreeSet<i32>>());
+
+    assert_pending!(fut.poll());
+
+    tx.send(2).unwrap();
+    assert!(fut.is_woken());
+    assert_pending!(fut.poll());
+
+    tx.send(1).unwrap();
+    assert!(fut.is_woken());
+    assert_pending!(fut.poll());
+
+    drop(tx);
+    assert!(fut.is_woken());
+    let coll = assert_ready!(fut.poll());
+    assert_eq!(BTreeSet::from([1, 2]), coll);
+}
+
 #[tokio::test]
 async fn collect_string_items() {
     let (tx, rx) = mpsc::unbounded_channel_stream();