in reply to
Pre-Qualifying Perl Questions
This is a question which comes up rather frequently.
Since I don't have refs at the tip of my tongue, suggest you use Google (for this site only) or Super Search with search terms such as employ (or employment) + interview.
On the other hand, as your third sentence acknowledges, you'll have to know Perl well (or have a grader who does) to make any "real-time" quiz useful... and even that won't tell you whether the individual is like one of my (former) fire-fighters: able to quote almost any sort of arcane datum relating to fire service matters... but utterly worthless on a call.