Simple tests (what is this jquery doing? why is this ruby script failing?) are great as bogofilters as long as you actually use jquery and ruby on the job.
I interviewed somewhere a few months ago and had a former programmer turned product manager grill me about b-trees (this was a Ruby on Rails position). I was not surprised to hear later that he was the one who gave me the final thumbs-down, I assume he thought I wasn't worth it because I didn't work at the same level of abstraction that he did when he was a coder.
He was seeing if you had a depth of understanding. I do that too.
I want to see that people are aware of what's going on below them. Not that it's just "magic" to some keyboard basher. ruby on rails attracts an extreme number of keyboard bashers, so they get extra scrutiny.
That's very different from grilling someone about b-trees, though. B-trees are fairly irrelevant to Rails development; it'd be like grilling the interviewee on assembly.
That's not to say that you don't need to weed out the people who only know how to recite various incantations to make magic happen; a knowledge of what's actually happening is very important. But at this level of abstraction, the correct focus should be on different, more relevant things: HTTP, caching, security, etc, which Rails (I'm guessing) handles for you but you should still know.
I get that, but when the interviewee is not just a "keyboard basher" then it suggests that the interviewer is the one lacking depth of understanding as they are conflating superficial ignorance with fundamental incompetence.
I interviewed somewhere a few months ago and had a former programmer turned product manager grill me about b-trees (this was a Ruby on Rails position). I was not surprised to hear later that he was the one who gave me the final thumbs-down, I assume he thought I wasn't worth it because I didn't work at the same level of abstraction that he did when he was a coder.