Unable to fetch to third party using Remix with error: TypeError: Expected signal to be an instanceof AbortSignal

[Afsoon]

Describe the bug
While I was trying to implement unit testing for my authenticate loaders and actions on my Remix project, I could not launch my test using Happy-DOM. I tried the same tests using JSDOM, and they passed without error.

After digging into the problem, I found the problem is that the AbortSignal and EventTarget classes don't implement the Symbol.toStringTag method. Remix is using this method to detect if the signal attached to a Request is an AbortSignal or EventTarget.

As a result, this check fails and throws an exception.

To Reproduce
Steps to reproduce the behavior (See Additional context for the link to the repository with the minimal code to reproduce it):

1. Create a loader that has a fetch to a third-party API
2. Create a test expecting the result of a loader
3. Launch the test, and it will fail with TypeError: Expected signal to be an instanceof AbortSignal

Expected behavior
I expected that it would work as on JSDOM.

Additional context
I made a repository where you can find a minimal reproduction of the bug and a possible workaround until a fix lands in the repository.

If it has low priority, I can make a PR to fix it. Nevermind, I had patched locally the package, I will open an PR ASAP with the fix.

This is the workaround

const Signal = new AbortSignal();

const SignalProxied = new Proxy(Signal, {
  get: (target, prop, receiver) => {
    if (prop === Symbol.toStringTag) {
      return "AbortSignal";
    }

    return Reflect.get(target, prop, receiver);
  },
});

const controller = new AbortController();
const ControllerProxied = new Proxy(controller, {
  get: (target, prop, receiver) => {
    if (prop === "signal") {
      return SignalProxied;
    }

    return Reflect.get(target, prop, receiver);
  },
});

global.AbortController = new Proxy(global.AbortController, {
  construct: () => {
    return ControllerProxied;
  },
});

The workaround is based on proxify AbortController and AbortSignal to intercept the call to the method Symbol.toStringTag