Cucumber

Cucumber is a testing framework which allows us to specify feature tests using plain language. We use Cucumber for e2e tests in some of our projects. We integrate it using the cucumber-rails gem.

Installing cucumber-rails

The installation process of cucumber-rails is also documented on its Github page.

To install cucumber-rails, add the following gems to your Gemfile:

group :test do
    gem 'capybara', require: false
    gem 'cucumber-rails', require: false
    gem 'database_cleaner'
end

Run bundle install to install the gems.

Finally, set up Cucumber with

rails generate cucumber:install

At this time, it is recommended to inspect the generated files and commit. Before committing, make sure, Rubocop does not raise any issues. Therefore, you will have to add the following exception to .rubocop.yml:

AllCops:
  Exclude:
    - 'lib/tasks/cucumber.rake'

Running your first Cucumber test

If you add Cucumber to an existing project, test a real page instead of using the given example test.

Add the following files:

• app/controllers/home_controller.rb (If you haven't done so already) in the RSpec section.
• features/home_check.feature
• features/step_definitions/home_check_steps.rb

Now, you can run Cucumber in your terminal:

cucumber

You may get a couple of deprecation warnings. There is currently an issue about them on the Github page of rspec-rails

Adding Cucumber tests to bin/check

Add the following code to bin/check, so the Cucumber tests are run on CI:

NO_COVERAGE=true bundle exec cucumber --format progress
if [ $? -ne 0 ]; then
  echo 'Cucumber did not run successfully, commit aborted'
  exit 1
fi

Assure that bin/check fails, if you have a broken Cucumber test.

Custom environment

Probably, you are going to need the following configuration files in /features/env:

• capybara.rb enables headless Chrome. This is needed in Cucumber tests which require Javascript (i.e. scenarios tagged with @javascript).
• database_cleaner.rb sets up database_cleaner for Cucumber tests.
• factory_bot.rb makes FactoryBot's methods (like build and create) accessible in the step definition file.
• warden.rb sets up the test environment, if you are using Warden (i.e. if you are using Devise).