text: import unittest
  from hamcrest import equal_to, assert_that
  from structural.bridge.abstraction import Letter, WikiPage, Article
  from structural.bridge.implementor import Paper, Audio, Web
  
  
  class TestClient(unittest.TestCase):
  
      def test_letter_paper(self):
          document = Letter()
          document.set_renderer(Paper())
          assert_that(document.create(), equal_to("This is a letter # on paper"))
  
      def test_article_web(self):
          document = Article()
          document.set_renderer(Web())
          assert_that(document.create(), equal_to("This is an article # in html"))
  
      def test_wiki_audio(self):
          document = WikiPage()
          document.set_renderer(Audio())
          assert_that(document.create(), equal_to("This is a wiki page # in audio"))
  
  