I've made similar tests for new employees, not for Perl but for other technical competency measurements. I don't use them in interviews, though.

I prefer to have a less formal interview. It should be a personal interaction so I can watch them think and react and formulate, and they can do the same of me. I may ask some technical issues and some political exercises (generic company politics, not world events).

However, I like to give this kind of test to a new hire. The test is a bit tougher and in-depth than the one you suggest above. I stress that they aren't expected to get everything right the first time, but they have a fixed period such as one month to become well-versed on the range of subjects presented. Some breeze through on the first day-- we usually knew they would. Some take the opportunity and time to learn what matters to the company-- we usually knew they would. Some demonstrate their deficiencies, not only in a lack of prior basics, but also in their inability to self-research and overcome gaps in their skillset.

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