A Whole New World

Cucumber runs scenarios in a World. By default, the World is just an instance of Object.

Step Definitions

All Step Definitions will run in the context of the current World instance. (A new instance is created for each scenario). This means that self in a Step Definition block will be the World instance. Any @instance_variable instantiated in a Step Definition will be assigned to the World, and can be accessed from other Step Definitions.

A better world

If you want to add any behaviour to the world, perhaps some helper methods, or logging, or whatever you can do this in support/env.rb:

class CustomWorld
  def a_helper
    ...
  end
end

World do
  CustomWorld.new
end

Now you can call a_helper from your step definitions. Note that every scenario is run in a separate instance of the world, so there is no implicit state-sharing from scenario to scenario.

You can also include modules in your World:

module MyHelper
  def some_other_helper
    ...
  end
end

class CustomWorld
  include MyHelper

  def a_helper
    ...
  end
end

World do
  CustomWorld.new
end

Several other frameworks such as Webrat or RSpec have modules that provide special methods that you can include in your World this way.

If you don’t want to define your own World class (and just use the default Object instances), you can still include modules in your World instances without polluting Object with a global include:

module MyHelper
  def some_other_helper
    ...
  end
end

module MyOtherHelpers
  def helper_b
    ...
  end
end

World(MyHelper, MyOtherHelpers)

This will extend each new World object with those modules.

If you use Ruby on Rails, there is already a World set up for you, so you will get an instance of Cucumber::Rails::World, which is a subclass of ActionController::IntegrationTest. This gives you access to a lot of Rails’ helper methods.

Related blog posts

• Building a better World