This Rails application lists out all the numbers from one to a million in multiple languages and page sizes.
Written using Ruby 2.4.1, although lower ruby versions should be compatible.
To run the application (assuming you have ruby and bundler installed);
> bundle install
> bundle exec rails s
then go to http://localhost:3000/
The test suites can be run by executing;
> bundle exec rails test
> bundle exec rails rspec