UploadedFile from string when testing

I came across this https://gist.github.com/waska14/8b3bcebfad1f86f7fcd3b82927576e38 which converts a string into a Illuminate\Http\UploadedFile. However, it writes to the disk as part of the process and deletes it before terminating.

Is there a more direct way of doing this? Thank you.