The class is just a shortcut to whatever strategy you use - it is generated using runtime. To load the config (and generate this class), you need to call
Strategy::initialize();
before. This can be done in a global controller for instance.
A good place to look is tests/unit/features/* - you can see how things are used there. You might to take a look at BusinessRulesTest.php in the first place because though all of them are advanced examples, this is the easiest one