How to properly reference service in angularjs jasmine unit test

inside a jasmine unit test, we usually saw this sort of _service_ inside the inject for angular.mock.

But I am still not sure how this works?

For example, the parameter _myService_ would be resolved as the reference myService. Since it is available in the function body as myService, we can then assign it to a variable defined in an outer scope.

In the official doc, it say above, however, does it means, ANY service that is inside already injected module, we should always reference like _MyServiceName_? How exactly this MyServiceName is getting from? Should we do something before we inject it? That's where I got confused.