Well, I would suggest
time travel as a sort of test... ;)
However, I'm not big on this stuff, but I do seem to know that they are able to carbon date fossils that they find in the ground... It seems as though they can use this to prove evolution, whether there's some sort of test or not. I would like to point out that since evolution is such a slow process, it's impossible to just say "BAM!" and make a test that a high school student can do in one class period.
And since you brought up genes... Isn't it partially the dominant genes that control evolution? For instance, way into the future, I predict that white people will just disappear because their skin color is recessive. We will evolve into a colored race because, as time goes by and people continue to intermix, the black and asian (and indian, etc.) traits will dominate.
We can already see this beginning to happen, and... well... I don't know if that's sufficient proof for you, but it is for me.