I had to comment out some gems which don't work with Rubinius, all stuff I use only in development (byebug, binding_of_caller, did_you_mean). There is a Rubinius debugger but I didn't try it http://rubini.us/doc/en/tools/debugger/
I had to remove the space after the arrow in lamba definitions like -> ()
Then I run rake spec. I bumped into a few show stoppers here.
One is due to some compatibility issues with the mail gem. There is an open issue on GitHub about that and it should be fixed in the gem. In general, if gems don't support Rubinius reliably we can't use it. And if we can't use it many gems won't have an incentive of testing against it.
The second one is that I got an overall feeling that Rubinius is slow. The examples include many integration tests with capybara and the js driver. Rubinius runs them in 7 minutes and 13 seconds (with spring) without the ones that failed. RMI 2.1.4 runs them in 1' 54" (all examples green). Maybe it's slow only for this kind of workload but such a difference in testing is hardly bearable. Too bad.
I'm not using rubinius yet either, but I think there is already a compelling case to take a serious look at it.
By the way, I googled a little and removing simplecov shaved a couple of minutes out of the rake spec times. Still too slow and very inconvenient, even if I can still use simplecov with MRI thanks to conditionals like if RUBY_ENGINE == "ruby" ... end
