gistfile1.builder

require 'rubygems'
require 'spec'

class Baz
  def call_foo_on(subject)
    block = lambda { |a| a * 2 }
    subject.foo(&block)
  end
end

describe Baz do
  class FakeCollaborator
    def foo(&block)
      @block = block
    end
    
    def block_ok?
      @block.call(2) == 4
    end
  end
  
  it "passes a block to the collaborator which doubles numbers" do
    collaborator = FakeCollaborator.new
    Baz.new.call_foo_on(collaborator)
    collaborator.block_ok?.should be_true
  end
end