So I started looking in C++ world and found http://igloo-testing.org which looks interesting but does not seem to be widely used.
I know JUCE has some unit testing functionality, however I do value being able to run a whole user story for integration tests, written in easy to read language that is seperate to the code.
I'd be interested to read peoples take on this sort of stuff here. I realise, that certain things are quite hard to test e.g. user turns filter cutoff knob, user hears filtered output.. but for general stuff like loading up, opening files, talking to an API etc I think it can be really useful.