1 files changed, 32 insertions, 0 deletions
diff --git a/third_party/rust/futures/tests/stream.rs b/third_party/rust/futures/tests/stream.rs
new file mode 100644
index 0000000000..fd6a8b6da7
--- /dev/null
+++ b/third_party/rust/futures/tests/stream.rs
@@ -0,0 +1,32 @@
+use futures::executor::block_on;
+use futures::stream::{self, StreamExt};
+
+#[test]
+fn select() {
+    fn select_and_compare(a: Vec<u32>, b: Vec<u32>, expected: Vec<u32>) {
+        let a = stream::iter(a);
+        let b = stream::iter(b);
+        let vec = block_on(stream::select(a, b).collect::<Vec<_>>());
+        assert_eq!(vec, expected);
+    }
+
+    select_and_compare(vec![1, 2, 3], vec![4, 5, 6], vec![1, 4, 2, 5, 3, 6]);
+    select_and_compare(vec![1, 2, 3], vec![4, 5], vec![1, 4, 2, 5, 3]);
+    select_and_compare(vec![1, 2], vec![4, 5, 6], vec![1, 4, 2, 5, 6]);
+}
+
+#[test]
+fn scan() {
+    futures::executor::block_on(async {
+        assert_eq!(
+            stream::iter(vec![1u8, 2, 3, 4, 6, 8, 2])
+                .scan(1, |acc, e| {
+                    *acc += 1;
+                    futures::future::ready(if e < *acc { Some(e) } else { None })
+                })
+                .collect::<Vec<_>>()
+                .await,
+            vec![1u8, 2, 3, 4]
+        );
+    });
+}