Any programmer who considers such a trivial test a large burden, you don't want. There's no other way to assess programming ability than programming, it's really that simple. If you hire an unknown programmer without making him submit a code sample, then you deserve what you get because you're gambling and likely to lose. The whole point is to find good programmers, and good programmers enjoy programming, they'll happily write a trivial program to prove it, happily. Anyone who balks at such a test is not someone you want to hire, period.