Function check_empty_read_yields_none 

pub async fn check_empty_read_yields_none<S, C, F, Fut>(factory: &F)
where
    S: RawEventStore + WakeSource,
    C: Send,
    F: Fn() -> Fut + Send + Sync,
    Fut: Future<Output = (S, C)> + Send,

A fresh, empty stream reads back empty (absent stream = empty, not error).