test.cr

abstract class StoragePageLayout
  include Lucky::HTMLBuilder
  getter view = IO::Memory.new
  
  abstract def content
  
  def render
    html_doctype

    html do
      head do
      body do
        content
      end
    end
  end
  
  def render_to_string
    String.build do |io|
      @view = io
      render
    end
  end
end

class Thing::IndexPage < StoragePage
  def render
    h1 "hi"
  end
end

Thing::IndexPage.new.render_to_string