Gemfile specified 2.1, but for some reason this didn't work with 2.1.5; needed to tweak the Gemfile to get it to work.
Just finished basic_enum.rb - got stuck in a handful of places, but not too tough. Moving on to the next thing.
Just finished arrays.rb. It went a lot faster than basic_enum, and not just because there were fewer tests.
Completed nested.rb, and now trying to make a new test for the last (untested) method.
Wrote & passed a new test for the 'person_with_most_experience_in_language' method