async Task <Stream> AppendAndWaitUntilChanged(FlowKey key, Event e, TestTimeline timeline)
{
var connectionId = Id.FromGuid();
await _queryDb.SubscribeToChanged(connectionId, QueryETag.From(key));
var position = await timeline.Append(e);
var newETag = QueryETag.From(key, position);
await _notifier.WaitUntilChanged(connectionId, newETag);
_queryDb.UnsubscribeFromChanged(connectionId);
return(await _queryDb.ReadContent(newETag));
}
public void UnsubscribeFromChanged(string key) => _db.UnsubscribeFromChanged(ConnectionId, FlowKey.From(key, _area));
