appraise "rails-3" do
  gem "rack", "< 2"
  gem "rails", "3.2.22.2"
end

appraise "rails-4" do
  gem "rack", "< 2"
  gem "rails", "~> 4.2.6"
end

appraise "rails-5" do
  gem "rails", "~> 5.0.0"
end