https://github.com/trentmwillis/ember-exam#split-test-parallelization
Inspired by https://stackoverflow.com/questions/49039442/firefox-browser-disconnect-issue-when-running-tests-via-testem
This coding works though needs to be more robust.
Regarding split test parallelization overall found that Chrome 67 worked better than Firefox 60 but was still an interesting experience regardless of which used. Also, without having actual different containers to run the parallelization in everything is running within the same resource pool so isn't practically any more performant.
To use this save the script into a file named whatever (run-tests.js for example) and then modify your package.json from