How to sleep without blocking the main thread in async tests

[GordianDziwis]

nvim-oxi/tests/src/libuv/timer_handle.rs

Lines 20 to 30 in b1278b1

	// TODO: how do sleep without blocking the main thread?
	// sleep(timeout / 2);
	//
	// assert_eq!(rx.try_recv().unwrap(), ());
	//
	// sleep(timeout / 2);
	//
	// for _ in 0..10 {
	// assert_eq!(rx.try_recv().unwrap(), ());
	// assert_eq!(rx.try_recv().unwrap_err(), mpsc::TryRecvError::Empty);

This worked for me:

    api::command("sleep 2")?;