templater.rb

module Templater
  extend self

  def render_template(template, opts = {})
    Tilt.new(build_file(template, opts)).render.inspect.split("\\n").join
  end

  private
  def build_file(file, opts)
    relative_path = opts[:path] || "/app/views/templates"
    extension = opts[:extension] || ".html.haml"
    File.join Rails.root, "#{relative_path}/#{file.to_s}#{extension}"
  end
end

templater_spec.rb

require 'spec_helper'

describe Templater do
  describe "render_template" do
    it "should render out a haml template when given a file that has a div" do
      template = Templater.render_template(:test, path: "/spec/support")
      template.should include("div")
    end
  end
end

templates.js.coffee.erb

window.JST =
    open_chat: <%= Templater.render_template :open_chat %>
    message: <%= Templater.render_template :message %>

test.html.haml

.test Test

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