Extract method to make codeclimate happy

Author: inclooder

lib/rails_erd/domain.rb

@@ -140,11 +140,7 @@ def check_association_validity(association)
       association.check_validity!
 
       if association.options[:polymorphic]
-        entity_name = association.class_name
-        entity = entity_by_name(entity_name)
-        if entity.nil? || entity.generalized?
-         raise "polymorphic interface #{entity_name} does not exist"
-        end
+        check_polymorphic_association_validity(association)
       else
         entity_name = association.klass.name # Raises NameError if the associated class cannot be found.
         entity_by_name(entity_name) or raise "model #{entity_name} exists, but is not included in domain"
@@ -153,6 +149,14 @@ def check_association_validity(association)
       warn "Ignoring invalid association #{association_description(association)} (#{e.message})"
     end
 
+    def check_polymorphic_association_validity(association)
+      entity_name = association.class_name
+      entity = entity_by_name(entity_name)
+      if entity.nil? || entity.generalized?
+        raise "polymorphic interface #{entity_name} does not exist"
+      end
+    end
+
     def association_description(association)
       "#{association.name.inspect} on #{association.active_record}"
     end