Espresso cheat sheet will help you write your tests and what you want to test:
Also always a good place for reference is the official documentation:
Advanced espresso video suggestions by Google: https://www.youtube.com/watch?v=isihPOY2vS4
Watchout: not using the "Espresso" version won't do anything when used outside a ViewAction. This may not be obvious if you have an import on the ViewAction version since they have exactly the same method name.