Support code to demonstrate issue reported on troessner/reek

Introduction to Support Code for Reported reek Issue.md

Tim and team,

This should be pretty straightforward, but here goes. We use module namespaces and nested classes (too?) extensively in our project, but very rarely make direct use of inheritance. One place we do is illustrated by the following two files.

Prolog::Core::User::Validators::Name::Whitespace is a class that, obviously, defines a protocol to check for impermissible whitespace in a string. It has two methods, #invalid_spacing? and #reason, that must be overridden by subclasses that implement the protocol. Such a class is Prolog::Core::User::Validators::Name::TrailingWs; it implements only those two methods, which are declared private as documentation that they'll never be called ordinarily by outside code.

Reek doesn't like that:

$ reek --version
reek 3.9.1
$ reek lib/prolog/core/user/validators/name/trailing_ws.rb
lib/prolog/core/user/validators/name/trailing_ws.rb -- 6 warnings:
  [15]:UnusedPrivateMethod: Prolog::Core::User has the unused private instance method `invalid_spacing?` [https://github.com/troessner/reek/blob/master/docs/Unused-Private-Method.md]
  [19]:UnusedPrivateMethod: Prolog::Core::User has the unused private instance method `reason` [https://github.com/troessner/reek/blob/master/docs/Unused-Private-Method.md]
  [15]:UnusedPrivateMethod: Prolog::Core::User::Validators::Name has the unused private instance method `invalid_spacing?` [https://github.com/troessner/reek/blob/master/docs/Unused-Private-Method.md]
  [19]:UnusedPrivateMethod: Prolog::Core::User::Validators::Name has the unused private instance method `reason` [https://github.com/troessner/reek/blob/master/docs/Unused-Private-Method.md]
  [15]:UnusedPrivateMethod: Prolog::Core::User::Validators::Name::TrailingWs has the unused private instance method `invalid_spacing?` [https://github.com/troessner/reek/blob/master/docs/Unused-Private-Method.md]
  [19]:UnusedPrivateMethod: Prolog::Core::User::Validators::Name::TrailingWs has the unused private instance method `reason` [https://github.com/troessner/reek/blob/master/docs/Unused-Private-Method.md]
$

Almost beside the point is that tests using the code show it works properly, and that Reek is so deeply confused it reports warnings against the class and each containing class. What gives here?

trailing_ws.rb

require_relative 'whitespace'

module Prolog
  module Core
    # This is the base "User" domain logic in Meldd, whether a member or guest.
    class User
      module Validators
        # Validations for a user name, wrapped up in a command-pattern class.
        class Name
          # Determines if name is invalid due to trailing whitespace.
          class TrailingWs < Whitespace
            private

            def invalid_spacing?
              name != name.rstrip
            end

            def reason
              :trailing_whitespace
            end
          end # class Prolog::Core::User::Validators::Name::TrailingWs
        end # class Prolog::Core::User::Validators::Name
      end
    end # class Prolog::Core::User
  end
end

whitespace.rb

module Prolog
  module Core
    # This is the base "User" domain logic in Meldd, whether a member or guest.
    class User
      module Validators
        # Validations for a user name, wrapped up in a command-pattern class.
        class Name
          # Class to DRY up similar whitespace-validation checks for name.
          class Whitespace
            def initialize(name:, publish:)
              @name = name
              @publish = publish
            end

            def call
              invalid_spacing?.tap { |ret| report_invalid_spacing if ret }
            end

            private

            attr_reader :name, :publish

            def invalid_spacing?
              message = 'You MUST override the #invalid_spacing? method!'
              fail NoMethodError, message
            end

            def reason
              fail NoMethodError, 'You MUST override the #reason method!'
            end

            def report_invalid_spacing
              publish.call :user_field_invalid, :name, reason, name
            end
          end # class Prolog::Core::User::Validators::Name::Whitespace
        end # class Prolog::Core::User::Validators::Name
      end
    end # class Prolog::Core::User
  end
end