I you are using googletest, you owe it to yourself to check out catch2 which I find much better and uses modern C++. There are a few other test frameworks in C++ that look better than google test as well, but catch2 is the one I settled on (and seems to be the best supported): feel free to check them out.
I've given up on mock frameworks. They make it too easy to make an interface for everything and then test that you are calling functions with the expected parameters instead of the program works as you want. A slight change to how I call some function results in 1000 failed tests and yet I'm confident that I didn't break anything the user could notice (sometimes I'm wrong in this confidence - but none of the failing tests give me any clue that I'm wrong!)
I've given up on mock frameworks. They make it too easy to make an interface for everything and then test that you are calling functions with the expected parameters instead of the program works as you want. A slight change to how I call some function results in 1000 failed tests and yet I'm confident that I didn't break anything the user could notice (sometimes I'm wrong in this confidence - but none of the failing tests give me any clue that I'm wrong!)