create_routes

# File actionpack/lib/action_dispatch/testing/assertions/routing.rb, line 46
          def create_routes
            app = self.app
            routes = ActionDispatch::Routing::RouteSet.new
            rack_app = app.config.middleware.build(routes)
            https = integration_session.https?
            host = integration_session.host

            app.instance_variable_set(:@routes, routes)
            app.instance_variable_set(:@app, rack_app)
            @integration_session = Class.new(ActionDispatch::Integration::Session) do
              include app.routes.url_helpers
              include app.routes.mounted_helpers
            end.new(app)
            @integration_session.https! https
            @integration_session.host! host
            @routes = routes

            yield routes
          end