delegator.rb

module Test
  class Base
    def hello
      puts 'Hello'
    end
  end

  Application = Base.new

  module Delegator
    def self.delegate(*methods, to:)
      Array(methods).each do |method_name|
        define_method(method_name) do |*args, &block|
          to.send(method_name, *args, &block)
        end

        private method_name
      end
    end

    delegate :hello, to: Application
  end
end

include Test::Delegator