_thing.html.erb

#!/usr/bin/erb

<%= yield %>

#!/usr/bin/env ruby
# frozen_string_literal: true

require "action_controller"
require "action_view"

class TestController < ActionController::Base
  self.view_paths = "."
  def _prefixes; []; end # Search the current directory rather than "test/"
end

cv = TestController.new.view_context

puts cv.render("thing") { "<%= yield %>".html_safe }

# vim: ft=ruby