This doesn't seem like that bad of an idea. One of the bigger problems with tests is that they tend to become a terrible metric once people start preparing for them specifically (and test-prep can suck the oxegyn out of real education). If the students and teachers don't care about the test, it is much easier (but still difficult) to make a test that gives useful feedback to the school system. Of course, you want students to take it seriously enough while there taking it.