I was getting this error in Travis CI.

 1) Jobs Management when user is not logged he publishes a job
     Failure/Error: visit root_path
     Rack::Timeout::RequestTimeoutError:
       Request ran for longer than 15000ms
     # ./spec/features/jobs_management_feature_spec.rb:9:in `block (3 levels) in <top (required)>'

Moving the rack-timeout gem to the staging/production group fixed it.

group :staging, :production do
  gem 'rack-timeout'
end

Credits: this issue.