Extract saas helpers into a concern

app/controllers/application_controller.rb

@@ -4,6 +4,7 @@ class ApplicationController < ActionController::Base
   include Authorization
   include CurrentRequest, CurrentTimezone, SetPlatform
   include TurboFlash, ViewTransitions
+  include Saas
 
   stale_when_importmap_changes
   allow_browser versions: :modern

app/controllers/concerns/saas.rb

@@ -0,0 +1,11 @@
+module Saas
+  extend ActiveSupport::Concern
+
+  included do
+    helper_method :signups_allowed?
+  end
+
+  def signups_allowed?
+    defined?(Signup) && defined?(saas)
+  end
+end

app/controllers/sessions_controller.rb

@@ -18,7 +18,7 @@ class SessionsController < ApplicationController
       magic_link = identity.send_magic_link
       flash[:magic_link_code] = magic_link&.code if Rails.env.development?
       redirect_to session_magic_link_path
-    elsif defined?(Signup) && defined?(saas)
+    elsif signups_allowed?
       Signup.new(email_address: email_address).create_identity
       session[:return_to_after_authenticating] = saas.new_signup_membership_path
       redirect_to session_magic_link_path

app/views/sessions/menus/show.html.erb

@@ -24,7 +24,7 @@
       <p class="margin-none-block-start">You don’t have any Fizzy accounts.</p>
     <% end %>
 
-    <% if defined?(saas) %>
+    <% if signups_allowed? %>
       <div class="margin-block-start">
         <%= link_to saas.new_signup_membership_path, class: "btn btn--plain txt-link center txt-small", data: { turbo_prefetch: false } do %>
           <span>Sign up for a new Fizzy account</span>