I’d say it depends on how exactly you want to set up the test. Do you plan to present each learner with an individual selection of questions or something like 3 levels, e.g. “Beginner”, “Advanced” and “Expert”? The latter should be easier to do. You write that you want ONE test. Is there a reason for that? A Lectora course can easily have several tests for each level, but also one test with a section for each level. Both ways you can calculate a LMS score from the separate test or section scores. Skipping questions is more difficult to handle because skipped questions are still part of the test and will be evaluated as “incorrect” when empty.