Question Any good examples and best practices of Unity Integration Tests?

I was going to start implementing automated integration tests into a fairly complex project, and I was trying to make sure I'm doing it the right way. Unit Tests are a bit more cut and try because it's easy to say how they're done when they're all so small, but integration tests are a different story. If I'm testing interdependent functionalities of my project, how do I do it? Should I make a lot of test scenes? Should I instantiate prefabs? Should I try to mock as much as possible and rewrite code to accommodate?