circle.yml

dependencies:
  cache_directories:
    - '~/.rvm/rubies'
    - 'vendor'

  override:
    - >
      case $CIRCLE_NODE_INDEX in
       0)
         rvm-exec 2.3.8 gem install bundler
         rvm-exec 2.3.8 bash -c "bundle check --path=vendor/bundle_2.3 || bundle install --path=vendor/bundle_2.3"
         ;;
       1)
         rvm-exec 2.4.5 gem install bundler
         rvm-exec 2.4.5 bash -c "bundle check --path=vendor/bundle_2.4 || bundle install --path=vendor/bundle_2.4"
         ;;
       2)
         rvm-exec ruby-head gem install bundler
         rvm-exec ruby-head bash -c "bundle check --path=vendor/bundle_head || bundle install --path=vendor/bundle_head"
         ;;
      esac

test:
  override:
    - case $CIRCLE_NODE_INDEX in 0) rvm-exec 2.3.8 bundle exec rake ;; 1) rvm-exec 2.4.5 bundle exec rake ;; 2) rvm-exec ruby-head bundle exec rake ;; esac:
        parallel: true