old_contents: """
  Middleware tests.
  
  """
  from flask import url_for
  from hamcrest import (
      assert_that,
      equal_to,
      is_,
  )
  from microcosm.api import create_object_graph
  
  
  def test_forwarding():
      graph = create_object_graph("test", testing=True)
      graph.use(
          "flask",
          "port_forwarding",
      )
  
      @graph.app.route("/", endpoint="test")
      def endpoint():
          return url_for("test", _external=True)
  
      client = graph.app.test_client()
      response = client.get(
          "/",
          headers={
              "X-Forwarded-Port": "8080",
          },
      )
  
      assert_that(response.status_code, is_(equal_to(200)))
      assert_that(response.data, is_(equal_to("http://localhost:8080/")))
  
new_contents: """
  Forwarding tests.
  
  """
  from flask import url_for
  from hamcrest import (
      assert_that,
      equal_to,
      is_,
  )
  from microcosm.api import create_object_graph
  
  
  def test_forwarding():
      graph = create_object_graph("test", testing=True)
      graph.use(
          "flask",
          "port_forwarding",
      )
  
      @graph.app.route("/", endpoint="test")
      def endpoint():
          return url_for("test", _external=True)
  
      client = graph.app.test_client()
      response = client.get(
          "/",
          headers={
              "X-Forwarded-Port": "8080",
          },
      )
  
      assert_that(response.status_code, is_(equal_to(200)))
      assert_that(response.data, is_(equal_to("http://localhost:8080/")))
  
subject: update doc string