Adding tests

tests/timeout_future.rs

@@ -0,0 +1,27 @@
+#![cfg(feature = "unstable")]
+
+use std::time::Duration;
+
+use async_std::prelude::*;
+use async_std::future;
+use async_std::task;
+
+#[test]
+fn should_timeout() {
+    task::block_on(async {        
+        let fut = future::pending::<()>();
+        let dur = Duration::from_millis(100);
+        let res = fut.timeout(dur).await;
+        assert!(res.is_err());
+    });
+}
+
+#[test]
+fn should_not_timeout() {
+    task::block_on(async {        
+        let fut = future::ready(0);
+        let dur = Duration::from_millis(100);
+        let res = fut.timeout(dur).await;
+        assert!(res.is_ok());
+    });
+}