gistfile1.rb

# -------------------------------------
# DECLARATION

# using strings for explicit inclusion
shared 'logged in as admin' do
  before { login_as admin_user }
end

shared 'a model with a slug' do
  it 'sets the slug column upon initialization' do
    described_class.new.slug.should_not be_blank
  end
end

# adding metadata for implicit inclusion
shared 'with admin user defined', :type => :controller do
  let(:admin_user) { Factory(:user, :role => 'admin') }
end

# possible aliases
alias_method :shared_context, :shared # instead of for_groups_matching
alias_method :shared_examples, :shared

# backward compatibility
alias_method :shared_examples_for, :shared

# -------------------------------------
# INCLUSION

# in spec/controllers/widgets_controller_spec.rb
# ^^ implicitly adds :type => :controller
describe WidgetsController do
  before do
    # admin_user is made available implicitly due to :type => :controller 
    login_as admin_user
  end
  # ...
end

# .. or ..

describe WidgetsController do
  describe "GET index" do
    # explicit inclusion in current example group
    include_context "logged in as admin"

    # ...
  end
end

# in spec/models/post_spec.rb
describe Post do
  # generates a nested group
  it_behaves_like 'a model with a slug'
end