Function exercise 

pub async fn exercise(
    store: impl Service<CreateCollection, Output = Collection, Error = Box<dyn Error + Sync + Send>>,
)

Available on crate feature inspect and (crate features test-utils) only.

Exercise the storage contract: cancelled appends publish nothing, ranges clamp and reject reversal, concurrent appends stay isolated, a stalled collection does not block another, and readers outlive their store.