Setup some infrastructure for testing multiple rails versions

Gemfile

+# frozen_string_literal: true
+# A sample Gemfile
+source "https://rubygems.org"
+
+# Allow the rails version to come from an ENV setting so Tavis can test multiple
+# versions. Inspired by http://www.schneems.com/post/50991826838/testing-against-multiple-rails-versions/
+rails_version = ENV['RAILS_VERSION'] || '3.2.22'
+rails_major = rails_version.split('.').first
+rails_gem = case rails_version
+            when "default" then
+              "~> 5.0.0"
+            else
+              "~> #{rails_version}"
+            end
+
+gem 'rails', rails_gem
+gem 'rspec-rails'
+gem 'sqlite3'
+
+# Need this for Rails 4 to get the JSON responses from the scaffold
+gem 'jbuilder' if rails_major == '4'
+

make_site.sh

+#!/bin/bash
+
+set -x
+
+# export RAILS_VERSION=3.2.0
+export RAILS_VERSION=4.0.0
+# export RAILS_VERSION=5.0.0
+major=$(echo $RAILS_VERSION | cut -d '.' -f1)
+
+rm Gemfile.lock
+bundle install
+
+bundle exec rails new sandbox --skip-gemfile --api -d sqlite3 --skip-bundle --skip-action-mailer --skip-puma --skip-action-cable --skip-sprockets --skip-javascript --skip-spring --skip-listen
+cd sandbox
+
+bundle exec rails generate scaffold Post title:string body:text
+
+if [ $major -eq 5 ]
+then
+  bundle exec rails db:create
+  bundle exec rails db:migrate
+else
+  bundle exec rake db:create
+  bundle exec rake db:migrate
+fi
+
+bundle exec rails server