add timeout stress test

tests/timeout.rs

@@ -0,0 +1,22 @@
+use std::time::Duration;
+
+use async_std::future::timeout;
+use async_std::task;
+
+#[test]
+fn timeout_future_many() {
+    task::block_on(async {
+        let futures = (0..100)
+            .map(|i| {
+                timeout(Duration::from_millis(i * 10), async move {
+                    task::sleep(Duration::from_millis(i)).await;
+                    Ok::<(), async_std::future::TimeoutError>(())
+                })
+            })
+            .collect::<Vec<_>>();
+
+        for future in futures {
+            future.await.unwrap().unwrap();
+        }
+    });
+}