How to wait for async updates to finish in a unit test

The code I am unit testing uses an async updater. Currently, my tests finish before handleAsyncUpdate gets called. This is my first foray into the async stuff so I am not too sure what to do here.

Edit: I added handleUpdateNowIfNeeded(); after triggering the update, and my tests passed after that. However I may still need to be able to wait for the update to happen and not use this handleUpdateNowIfNeeded(); route. I am relying on a value tree which is why I need to wait for the updates to happen as I need the value tree callbacks to be finished.