Eliminate reflection warnings from test suite

This obviously has no effect on functionality aside from an infinitesimal performance increase, but I think it's desirable to have clean test suite output without lots of spewing warnings, and to reduce the number of compiler warnings for users who use the library. With this patch, "lein test" passes with no warnings.

I am a Clojure newbie so I may have failed to follow proper style; feedback welcome if you have time to give any.