RAILS_VERSIONS = %w( 4.2.8 5.0.2 5.1.0 ) RAILS_VERSIONS.each do |version| appraise "rails_#{version}" do gem 'rails', version # http://stackoverflow.com/questions/43886586/minitest-plugin-rb9-getting-wrong-number-of-arguments gem 'minitest', '~> 5.10', '!= 5.10.2' end end