Remove the spaces after the open bracket and before the close bracket.

All our generated code follow this rule

Author: rafaelfranca

railties/lib/rails/generators/rails/scaffold_controller/templates/controller.rb

@@ -4,7 +4,7 @@
 <% end -%>
 <% module_namespacing do -%>
 class <%= controller_class_name %>Controller < ApplicationController
-  before_action :set_<%= singular_table_name %>, only: [ :show, :edit, :update, :destroy ]
+  before_action :set_<%= singular_table_name %>, only: [:show, :edit, :update, :destroy]
 
   # GET <%= route_url %>
   # GET <%= route_url %>.json