Could you update this and the blog article ? Many things has changed since 2017.
I try something similar of what you did, but using parcel to bundle the tests and launch on the browser.

Hi @vitalets, I just cloned this repo and tried to open index.html in my browser. Everything failed because none of the javascript files were allowed to be downloaded due to CORS. I don't understand how this could be useful if I need to set up a web server in order to run the tests. How did you get around this?

First of all, your article and example is very helpful. Thank you!

But as long as I import a node module, as any "real" project will do, it fails to work. For example I add

import debug from 'debug' to sum.js then I will get the error

Uncaught TypeError: Failed to resolve module specifier "debug". Relative references must start with either "/", "./", or "../".

Any idea how can I fix it ? The last resort of course will be using webpack to bundle them into a single file, but I was hoping if there is any easy solution without bundling.