Gemfile

# A sample Gemfile
source "https://rubygems.org"

# gem "rails"
gem 'haml'

poc.rb

require 'haml'


class Scope
  attr_accessor :locals
  def initialize
    self.locals = {}
  end
  def method_missing name, *args, &block
    puts block.nil?
    self.locals[name] = block.call
  end
end

def render template, &block
  engine = Haml::Engine.new template
  scope = Scope.new
  scope.instance_eval &block

  engine.render Object.new, scope.locals
end

poc_test.rb

require 'minitest/autorun'
# Load in your class to be tested
#require 'things'
require './poc'

class TKTest < Minitest::Test
  @object_html = "<img src='http://placehold.it/100' />"
  @body_html = "<p>Pellentesque habitant morbi tristique<p>"
  def setup
    # Set up some test conditions here
    # This will be invoked before each test
  end

  #def test_scope
    #scope = Scope.new
    #scope.instance_eval do
      #object do
        #object_html
      #end
      #body do
        #body_html
      #end
    #end
    #assert_equal scope.locals[:object], object_html
    #assert_equal scope.locals[:body], body_html
  #end

  def test_render
    template = """
.media.media--list
  .media__object
    = object
  .media__body
    = body
    """
    html = render template do
      object do
        "<img src='http://placehold.it/100' />"
      end
      body do
        "<p>Pellentesque habitant morbi tristique senectus et netus et malesuada fames ac turpis egestas. Vestibulum tortor quam, feugiat vitae, ultricies eget, tempor sit amet, ante. Donec eu libero sit amet quam egestas semper. Aenean ultricies mi vitae est. Mauris placerat eleifend leo.<p>"
      end
    end
    puts html
  end

 def teardown
   # This will be invoked after each test
   # Use to close connections, etc.
 end
end