Cucumber Core is the inner hexagon for the Ruby flavour of Cucumber.

It contains the core domain logic to execute Cucumber features. It has no user
interface, just a Ruby API. If you're interested in how Cucumber works, or in
building other tools that work with Gherkin documents, you've come to the right
place.

WWW: https://github.com/cucumber/cucumber-ruby-core
RG:  https://rubygems.org/gems/cucumber-core