The Stairs Test

A term used when writing Harry Potter fanfiction (mostly on Ao3) where a character finds out they're trans by going up the "wrong" stairs in the dorms of Hogwarts. The stairs only allow one gender to come up them (Male or female), and when a canonically Male character (primarily Harry) is able to go up the stairs in a fanfic, it serves to move the plot forward.

"I was reading a fanfic the other day, and the author included the stairs test"