Add single timeout test

tests/timeout.rs

@@ -0,0 +1,29 @@
+use std::io;
+use iou::sys;
+
+#[test]
+fn timeout_test() -> io::Result<()> {
+    let mut io_uring = iou::IoUring::new(2)?;
+
+    let mut sq = io_uring.sq();
+    let mut sqe = sq.next_sqe().unwrap();
+
+    // make a timeout
+    let timeout_spec: _ = sys::__kernel_timespec {
+        tv_sec:  0 as _,
+        tv_nsec: 2e8 as _,
+    };
+
+    unsafe { sqe.prep_timeout(&timeout_spec); }
+
+    io_uring.sq().submit()?;
+
+    // check that timeout reading works
+    {
+        let mut cq = io_uring.cq();
+        let cqe = cq.wait_for_cqe()?;
+        assert!(cqe.is_timeout());
+    }
+
+    Ok(())
+}