Redirect from one POST route to another POST route from a class method handler

I have two POST routes /test and /test_new. The objective is to redirect all incoming requests from /test_new to /test along with the body contents. Hence The following code aims to use a named route for redirection

$app->post('/test', function (Request $request, Response $response, $args) {
  return $response;

$app->post('/test_new', function (Request $request, Response $response, $args) use ($app) {
  $routeParser = RouteContext::fromRequest($request)->getRouteParser();
  // $routeParser = $app->getRouteCollector()->getRouteParser();
  return $response->withStatus(307)->withBody($request->getBody())
    ->withHeader('Location', $routeParser->urlFor('test'));

This piece of code fails with the message

/test_new - Uncaught RuntimeException: Cannot create RouteContext before routing has been completed in /home/biswa/test/test-slim/vendor/slim/slim/Slim/Routing/RouteContext.php:40

If I simply replace the $routeParser with the commented line in the second route handler and use the $app for the RouterParser it works fine. But In my actual code I have the handling logic in a class function and have no access to $app in there.

Can someone please help me to sort this out

Got the answer here