Ruby on Rails: Running a Single Cucumber Feature

This occurs to me from time to time and I hope it will be handy to other developers, too.

To run a single cucumber feature, specify the feature name using FEATURE environment variable.

cucumber -r features features/adding_products.feature

The reason we use -r features when running a single cucumber feature is that we need to require the directories of the features which contains step definitions and environment settings of Cucumber.