Adding an API endpoint for saving data

In this section, we’ll start by adding the POST request handler function for saving data and then continue with the PUT function, in its own route file, for updating data.

Let’s begin with a test helper:

1. Create a new file, src/factories/request.js, with the following content. This will be used by both the POST and PUT functions to read the data of the request. SvelteKit will pass a Request argument. The only bit of this we need to provide is the json method, as shown here:

   export const createRequest = (json) => ({
     json: () => Promise.resolve(json)
   });

Providing minimal versions of collaborating objects

SvelteKit passes the Request objects into our request handler functions. But for our unit tests we don’t need fully formed Request objects, we just need an object that implements the parts of the interface that we use. Our application code doesn’t use anything but the json method...