check_validity!

# File activerecord/lib/active_record/reflection.rb, line 900
      def check_validity!
        if through_reflection.nil?
          raise HasManyThroughAssociationNotFoundError.new(active_record.name, self)
        end

        if through_reflection.polymorphic?
          if has_one?
            raise HasOneAssociationPolymorphicThroughError.new(active_record.name, self)
          else
            raise HasManyThroughAssociationPolymorphicThroughError.new(active_record.name, self)
          end
        end

        if source_reflection.nil?
          raise HasManyThroughSourceAssociationNotFoundError.new(self)
        end

        if options[:source_type] && !source_reflection.polymorphic?
          raise HasManyThroughAssociationPointlessSourceTypeError.new(active_record.name, self, source_reflection)
        end

        if source_reflection.polymorphic? && options[:source_type].nil?
          raise HasManyThroughAssociationPolymorphicSourceError.new(active_record.name, self, source_reflection)
        end

        if has_one? && through_reflection.collection?
          raise HasOneThroughCantAssociateThroughCollection.new(active_record.name, self, through_reflection)
        end

        check_validity_of_inverse!
      end