language: ruby
before_install: gem install bundler -v 1.17.3
install: bundle install -j 4 --retry 3
script:
  - bin/rspec
matrix:
  include:
    - rvm: "1.9.3"
      gemfile: Gemfile-old-ruby
    - rvm: "2.0.0"
      gemfile: Gemfile-old-ruby
    - rvm: "2.1.0"
      gemfile: Gemfile-old-ruby
    - rvm: "2.1.5"
      gemfile: Gemfile-old-ruby
    - rvm: "2.2.1"
      gemfile: Gemfile-old-ruby
    - rvm: "2.2.2"
    - rvm: "2.3.0"
    - rvm: "2.3.3"
    - rvm: "2.4.1"
    - rvm: "2.5.7"
    - rvm: "2.6.5"