.gitlab-ci.yml

image: "ruby:2.5.1"

 Add Postgres and Selenium Docker services. A Firefox container is also available.
services:
  - postgres:latest
  - selenium/standalone-chrome:latest

 Set our environment variables. Note it's supplying where Gitlab's
 Docker service will make Selenium available at. The Postgres
 config matches a database.yml.gitlab we'll add later.
variables:
  POSTGRES_DB: "test_db"
  POSTGRES_USER: "runner"
  POSTGRES_PASSWORD: ""
  RAILS_ENV: "test"
  SELENIUM_URL: "http://selenium__standalone-chrome:4444/wd/hub"

# Cache gems in between builds. We use the project path slug
# as the key because one cache per project works well enough
# for us
cache:
  key: ${CI_PROJECT_PATH_SLUG}
  paths:
    - vendor/ruby

 Setup shell commands. We need nodejs for asset compilation,
 And libgmp for the bcrypt gem. Then we override the database
 configuration with our Gitlab configuration. Now, we can
 install our gem dependences, bundle to the vendor folder so we # can cache them, and finally prep the database.
before_script:
  - apt-get update -q && apt-get install nodejs libgmp-dev -yqq
  - cp config/database.yml.gitlab config/database.yml
  - gem install bundler rubocop --no-ri --no-rdoc
  - bundle install -j $(nproc) --path vendor
  - rails db:schema:load

 We have two jobs, first, we lint the project with Rubocop to
 keep us honest and clean
rubocop:
  script:
  - rubocop

 Then we run our RSpec suite. When we run tests against
 Selenium, Rails will save screenshots of failures. We capture
 Them as artifacts so we can grab them through Gitlab's UI
 later.
rspec:
  script:
  - rspec spec
  artifacts:
    when: on_failure
    expire_in: 1 week
    paths:
    - tmp/screenshots/
    - log/