Run from the root of the engine project:
rails generate cucumber:install --capybara
Edit features/support/env.rb and add to the top:
ENV["RAILS_ENV"] ||= "test"
require File.expand_path("../../../test/dummy/config/environment.rb", __FILE__)
ENV["RAILS_ROOT"] ||= File.dirname(__FILE__) + "../../../test/dummy"
Now from the root of the engine project:
cucumber features
Thanks for this!