Concern: Sample

mock_concern_class.rb

# -*- ruby encoding: utf-8 -*-

module MockConcernClass
  def mock_concern_class(mod)
    klass = Class.new
    klass.__send__(:include, mod)
    klass
  end

  def toggle_private_instance_methods_on(klass)
    klass.tap do
      if (pim = klass.instance_variable_get(:@__private_instance_methods__))
        klass.__send__(:private, *pim)
        klass.instance_variable_set(:@__private_instance_methods__, nil)
      else
        pim = klass.private_instance_methods
        klass.instance_variable_set(:@__private_instance_methods__, pim)
        klass.__send__(:public, *pim)
      end
    end
  end
  
  Minitest::Test.send(:include, self)
end

sample_concern.rb

# -*- ruby encoding: utf-8 -*-

module SampleConcern
  extend ActiveSupport::Concern

  included do
    # Things to be run when this is included, such as:
    #
    # include OtherConcern
    # validates …
    # validate …
  end

  module ClassMethods
    # Class methods to be defined against the class when this concern is
    # included. This allows those methods to be used as if they were Rails
    # 'keywords' (e.g., validates).
  end

  # Define methods and constants provided by the concern here.
end

sample_concern_spec.rb

# -*- ruby encoding: utf-8 -*-

require 'spec_helper'

describe SampleConcern do
  let(:klass) { toggle_private_instance_methods(mock_concern_class(SampleConcern)) }
  let(:subject) { klass.new }
end