instance method with_routing

# File actionpack/lib/action_dispatch/testing/assertions/routing.rb, line 22
          def with_routing(&block)
            old_routes = nil
            old_routes_call_method = nil
            old_integration_session = nil

            setup do
              old_routes = app.routes
              old_routes_call_method = old_routes.method(:call)
              old_integration_session = integration_session
              create_routes(&block)
            end

            teardown do
              reset_routes(old_routes, old_routes_call_method, old_integration_session)
            end
          end