I was taking a look at open jruby issues and how to contribute with adding Ruby 2.5 support, so I prepared this small pull request.
I believe this is not a priority right now since Ruby 2.5 is not released yet, but I decided to contribute anyway, so I'm eager to receive feedback and check if I'm going in the right direction with this.
Please consider this as a WIP, since I could not see the results of the introduced tests in Travis although is working fine for me when I manually tested it in jirb.
@nomadium I believe the code is alright. The tests themselves we actually get upstream from MRI. So while I merged those tests in they will at some point get wiped out when we resync with MRI.
The solutions to this problem is either:
If these were gotten from upstream then I guess that is d) and we will get them next time we sync with their test suite :)