This may look like a total beginner's project, but let me tell you, this specific repo solves a pretty particular problem related with the test of services that post data to a remote API.
Well the easy answer for this is that sometimes, the people we are working with havent develop the API intended to receive our data and return an especific response in relation to the status of the request etcetera. This may sound a little awkward, but it actually happens so here we are.
That's easy to answer, to initialize the server, just run yarn start or yarn dev. You should use this service alongside some kind generic domain like ngrok, and forward your post request to "/api/test". By doing so, you should be able to simulate the remote API you're expecting to reach.