rack-test >= 7.1 requires ruby >= 2.2.2

[kjhenner]

This may be filed under 'not my problem,' because it stems from dependencies outside of this project but in case it's useful I figure I may as well make a note here.

I've run into some issues running bundle install stemming from an open-ended requirement of rack-test in sinatra-contrib 1.4.7, which is required by this gem. Versions of rack-test greater than 7.0 require ruby >= 2.2.2, so when bundler tries to install the latest versions of rack-test, it fails on ruby < 2.2.2. It looks like sinatra-contrib is deprecated, so it seems unlikely that there will be a 1.4.x release that will include a more specific version requirement w/r/t this rack-test requirement.