modules_needing_included_method.rb

    # Any module (not class) that includes SemanticLogger::Loggable must also implement an
    # `included` method that gets the including class to also include SemanticLogger::Loggable.
    # This is because the module's instance method `logger`, when it becomes part of the including
    # class, will look for `self.class.logger` when called, and `self` will evaluate to the instance
    # of the class and not the module. Having the class include `Loggable` will cause a class method
    # `logger` to be created so that this will work.
    #
    # This method returns the modules that have included Loggable but do not have an `included`
    # method implementation. This is an imperfect test since we are not testing the content of that
    # implementation, but I don't know a better way.
    #
    # Since we are asking ObjectSpace for the modules, we are assuming that all modules we need
    # to test have already been loaded. I think this is a reasonable assumption.
    specify 'must force class that include modules using SemanticLogger to include Loggable' do
      suspicious_modules = ObjectSpace.each_object(Module).select do |object|
        # All Class'es are modules, but we are not interested in them, so we exclude them.
        !object.is_a?(Class) \
        && \
        object.ancestors.include?(SemanticLogger::Loggable) \
        && \
        !object.respond_to?(:included) \
        && \
        (!object.equal?(SemanticLogger::Loggable))
      end

      expect(suspicious_modules.map(&:name).sort.join("\n")).to eq('')
    end