celebrity_spec.rb

describe Celebrity do
  it_should_behave_like "A featured model"

  def sample_featurable_object
    create_celebrity
  end
end

organization_spec.rb

describe Organization do
  it_should_behave_like "A featured model"

  def sample_featurable_object
    create_organization
  end
end

spec_helper.rb

describe "A featured model", :shared => true do
  # notar que nunca defino "sample_featurable_object" aca adentro
  
  def featured
    @featured ||= sample_featurable_object
  end

  def feature
    @feature ||= Feature.create!(:featured => featured)
  end

  it "should raise when destroying a featured item" do
    lambda { featured.destroy }.should raise(ActiveRecord::SomeError) 
  end

  it "...?" do
    # other specs
  end
end