Using a combination of Bundler and some JRuby management or detection scheme — possibly using one of the popular Ruby managers like RVM or Uru — ensure the test suite can automatically validate all of the currently workable JRuby/Mirah combinations.
Desired combinations could be added to a "hot list" for automated testing.
Valid combinations can be added to the project documentation.
Invalid combinations can be (eventually) deprecated and removed from the documentation.
Using a combination of Bundler and some JRuby management or detection scheme — possibly using one of the popular Ruby managers like RVM or Uru — ensure the test suite can automatically validate all of the currently workable JRuby/Mirah combinations.