What you are doing in method number 2 is essentially what I do (I use google test though not catch).
If you are using cached values then that might explain the issue with the parameter not updating. I have had some issues dealing with value tree updates and cached values in my unit tests. If you are using cached values forcing the update of the cached value might work. You might take a look at this thread and check out Daves answer. I ended up using an async updater and calling handleUpdateNowIfNeeded in my tests and that seemed to work well.