Is there some kind of test equivalent to what the FizzBuzz test is for developers, for graphic designers? That is, a short and simple question/task that can be asked/assigned just to determine whether a candidate has the basic skills needed to be worth considering at all.
I was recently involved in helping to recruit a new designer and I was asked to design the part of the interview that would test for the right kind of practical creative thinking.
What I went with - which seemed to work quite well and got very useful results - was to give each candidate a plausible very basic brief (everyone gets the same one, naturally) and about 20 minutes in a room with pens, paper and a flipchart (no computers!), asking them to sketch out one or two initial ideas, then after they'd done so talk through not only their ideas, but what questions they would ask the client or account manager to develop the ideas further, and also about any ideas they came up with then decided against pursuing (with reasons). I made it very clear in the task brief that they wouldn't be judged at all on the quality quality of any drawings they made, and that it was all about the way they approached thinking about the task and developing ideas.
A few things to note about this:
But as a test for design ability that isn't related to things people can pick up on the job or with training like software skills, it did the job and seemed better than anything else I could find when I looked for ideas.
Edit - people have mentioned portfolios: looking through candidate's portfolios is still the most important test, but it's hardly foolproof, especially for seeing core aptitudes like creativity and composition.
Many junior designers work to a senior or art director's specifications and signoff, so for many (but not all) junior / lower-middleweight candidates, much of the portfolio will be someone else's creativity and attention to detail on show as well as the candidates'. You also need to take limitations imposed by clients into account - one candidate's portfolio might seem much more creative than another, but they might simply have been lucky to have more open-minded clients.
People sometimes include self-initiated, pro-bono and/or much earlier college/freelance work to be sure that there's plenty of work that is 100% their own, but not everyone will be able to do this.
I'd suggest considering using a test like above if:
Like coding, graphic design is really about creative thinking and problem solving.
Also like coding, any test you could give likely emphasizes implementation skills more so than creative thinking.
IMHO, these types of tests check for the understanding of particular code syntax or a particular piece of software...both skills that are easy to learn, so shouldn't be a major factor in whether you hire them or not.
In terms of finding designers you feel are worth considering or not, this is what their portfolio is for.