Add test

tests/timeout.rs

@@ -0,0 +1,17 @@
+use std::io;
+use std::time::{Duration, Instant};
+
+use polling::Poller;
+
+#[test]
+fn timeout() -> io::Result<()> {
+    let poller = Poller::new()?;
+    let mut events = Vec::new();
+
+    let start = Instant::now();
+    poller.wait(&mut events, Some(Duration::from_secs(2)))?;
+    let elapsed = start.elapsed();
+
+    assert!(elapsed >= Duration::from_secs(2));
+    Ok(())
+}