run middlewares and handler of express app with routes and get response without having to listen to a server

This is in continuation of the question here. https://stackoverflow.com/questions/76193074/middleware-and-stack-functions-invoker-for-expressjs-and-the-response-object-cap/76221423

Can I run middlewares and handler of express app with routes and get response without having to listen to a server

I have an express app like below:

var express = require("express")();


express.get("/test", (req, res) => {
        console.log("TESTING CLUSTER PROCESS ", process.pid);
        res.status(200).send(`{ 'hello': 'server', 'pid': ${process.pid} }`)
})

express.all("/", (req, res) => {
        console.log("TESTING CLUSTER PROCESS ", process.pid);
        res.status(200).send(`{ 'hello': 'server', 'pid': ${process.pid} }`)
})


module.exports = express;

something like this:

let req = new require("https://github.com/expressjs/express/blob/0debedf4f31bb20203da0534719b9b10d6ac9a29/lib/request.js")
req.path = "/";
req.header = {};
req.body = '{"test": "tester"}';


let res = new require("https://github.com/expressjs/express/blob/0debedf4f31bb20203da0534719b9b10d6ac9a29/lib/response.js")

let someresponse = router.handle(req, res);
console(someresponse);

I am wishing to use the app.handle(req, res, next) or the router.handle(req, res, next) and use the app routes wihtout having to listen to a server.

Is it possible for me to run the req-res function without using the creation of http/s server using this? I will create a request from fetch request (wish to mock this request object instead of fetch api https://github.com/expressjs/express/blob/0debedf4f31bb20203da0534719b9b10d6ac9a29/lib/request.js#L31 and response from this response object https://github.com/expressjs/express/blob/0debedf4f31bb20203da0534719b9b10d6ac9a29/lib/response.js#L43 to run the router.handle(req, res, next) and get the response without having to listen to a http sever.

Is it possible - logically with such app instances above?

request > request object > app (with routes, without listening) > process request to get response through route handler > response - is what I am trying to achieve

Lets say the goal is run the request object through the routes, middlewares, handlers, get the response without having to listen to the express server.

If you want to call router.handle(req, res, next) yourself, then you have to create your own req and res objects with all the properties and methods that Express (and any middleware libraries you might use) expects and uses. From Express' point of view, your manually created req and res objects must appear to be indistinguishable from the ones that the http server object would normally create (and with the methods that Express would add or override).

That means there needs to be incoming stream, an outgoing stream and whatever pre-parsed state the req object is expected to be in (presumably containing already parsed headers, but no body data) and all the appropriate properties and methods. Then, any body data (from a POST or PUT) must be in the req stream waiting to be read by your middleware or route handlers.

It's all doable, just a lot of grunt work to get right and then testing it thoroughly to see if you actually missed anything. Then, when something doesn't work properly you'll be wondering if your "fake" server implementation is the problem or if its actually a bug in your route handler.

And, of course, you have to create a next() callback function that has the appropriate behavior when called with and without a parameter.

Personally, I don't quite understand why you don't just create a local http server (with one simple function call) and let the http server object do all this work for you. You have not offered any motivation for why you want to do all this extra work so we can comment on other (perhaps better) ways to solve whatever problem you're trying to solve.