Hi Rachel:
Pretests can be valuable to both student and teacher. For the student, they can see the depth and breadth of upcoming topics, and perhaps begin to prepare for areas they think they might need extra study. For the teacher, results may reveal that unexpected areas of course content may need more emphasis or focus based on the testing. I think another benefit for both is pretesting can assist putting the teacher and student aligned with similar goals for successful outcomes.
Regards, Barry