I recently wrote about an experience helping with promotion testing at my sensei's dojo, where I had to work with a student who wasn't fully prepared. I had to find the path between challenging her and discouraging her when she could not remember her kata.
To continue the story: the next week, Jane's [not her real name] test continued. She still owed me the kata she'd been unable to show me, but first there was kumite -- sparring. After a couple a matches with other young, kyu-level students, our sensei sent Jane to line up against me.