How to add SimpleCov code coverage to Rails project.

Recently I added code coverage tool to Rails project to keep track of test coverage.

First, add simplecov gem to Gemfile then add following to spec_helper.rb, rails_helper.rb or test_helper.rb

require "simplecov"
SimpleCov.start "rails" do
  enable_coverage :branch
  add_group "ViewComponents", "app/components"
  add_group "Queries", "app/queries"
  add_group "Serializers", "app/serializers"
  add_group "Services", "app/services"
  add_group "Gateways", "app/gateways"
  add_group "Presenters", "app/presenters"
  add_group "Validators", "app/validators"
end

Above shows how one can organize report in groups.

In addition, enable_coverage :branch will show what code branches are not covered by tests.

More information can be found at simplecov

Thanks for reading!