I passed the oral part of my school-leaving exams two weeks ago. But for some reason, I keep dreaming of failing the test- showing up too late, not knowing the answers and in one case not even getting to any prep classes.

I didn't have any nightmares before the test, yet here they are. I even did really well on it- an A in every subject, I literally couldn't have done better. So why is it haunting me?

Tests and failing them are common dream symbols. The trick is trying to figure out what in your waking life generated the feelings that triggered them. Here are links to their definitions:

test: dreamdoctor.com/dream-dictionary/definitions/test.html
failing: dreamdoctor.com/dream-dictionary/definitions/failing.html

Hope that helps!