Yes, thank you very much for the idea. We didn't think about that, because we want the platform to be open to anyone. There is no problem with free courses - a prospective learner can just check them and see if they suit him/her. As regards to those that will have to be paid for, we will provide extensive previews.
However, we might include the possibility of some sort of testing (the content of which should be prepared by the lecturers themselves, of course) but which should not be decisive as to whether the aspiring learner can take a particular course or not. Such testing should be more for informative purposes and for guidance.