gistfile1.rb

    # Fake _target_ identity. This extends #is_a?, #kind_of?, #instance_of? on
    # _target_ and #=== on _pretended_klass_.
    #
    # Example: fake_identity YourCustomHash, Hash
    #
    # @param [Class] target class that is being given fake identity
    # @param [Class] pretended_klass class that target is pretending to be
    def self.fake_identity(target, pretended_klass)
      target.instance_eval do
        [:is_a?, :kind_of?, :instance_of?].each do |method|
          define_method(method) do |klass|
            klass == pretended_klass ? true : super(klass)
          end
        end
      end

      metaclass = class << pretended_klass; self; end
      metaclass.instance_eval do
        define_method(:===) do |object|
          if object.is_a?(target)
            true
          else
            super(object)
          end
        end
      end
    end