Configure Travis CI for Ruby on Rails

In this tutorial I am going to show you how to configure Travis CI to run your Rails’ test suite and system tests everytime you push a new change to your repository.

Create a Simple Rail Application

First we’ll need to create simple Rail application. Open up your terminal and run the following commands.

$ rails new rails-travis-ci-example -d=postgresql
$ rails db:create
$ rails g scaffold Post title body:text

This step will automatically generate tests and system tests.

$ rails db:migrate

Configure Rails Application to run System Tests in Travis CI

Rails is configured by default to run system tests in Google Chrome. However, I ran into an issue with Travis CI when it came to running system tests using the default configuration. My solution was to update test/application_system_test_case.rb by declearing :headless_chrome instead of the default :chrome setting.

Edit test/application_system_test_case.rb

# test/application_system_test_case.rb
   
require "test_helper"
   
class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
  # ℹ️ Use headless_chrome
  driven_by :selenium, using: :headless_chrome, screen_size: [1400, 1400]
end

Run the test suite locally to ensure it works and passes.
```
$ rails test
$ rails test:system
```

Configure Travis CI to run the Rails Test Suite and System Tests

Next we need to create a .travis.yml file in order for Travis CI to know how to build our application.

Creat a .travis.yml file and add the following:

language: ruby
cache:
  - bundler
  - yarn
services:
  - postgresql
before_install:
  - nvm install --lts
before_script:
  - bundle install --jobs=3 --retry=3
  - yarn
  - bundle exec rake db:create
  - bundle exec rake db:schema:load
script:
  - bundle exec rake test
  - bundle exec rake test:system

Key	Description
os	Sets the build’s operating system. Note that we did not add an `os` key, and are using the default environment
language	Selects the language support used for the build. We select `ruby` since this is a Rails project
cache	Activates caching content that does not often change in order to speed up the build process. We add `bundler` and `yarn` since Rails uses bundler and yarn to managage dependencies.
services	Services to set up and start. We add `postgresql` since our database is postgresql. You could also add `redis`.
before_install	Scripts to run before the install stage. We add `nvm install --lts` to use the latest stable version of Node. This will be needed when we run `yarn` later.
before_script	Scripts to run before the script stage. This sets up our Rails application. Note that I do not seed the database, since we only care about the test environment. I run `bundle install --jobs=3 --retry=3` instead of `bundle` becuase that’s what the documentation recommends.
script	Scripts to run at the script stage. In our case, we just run our tests.

Log into Travis CI and navigate to https://travis-ci.org/account/repositories.
Search for your repository, and it enabled. If your repository doesn’t appear click the Sync account button.

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Navigate to your project and trigger a build. Alternatively, make a new commit and push to GitHub to trigger a new build.

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If you’re using Heroku you can use GitHub as your deployment method and enable automatic deployments, but have it configured to wait for the CI to pass first.

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