Latest version of Happy DOM hangs Vitest

[capricorn86]

Describe the bug

First I just want to say that this is a great library and I have recommended it to a lot of people. It is also really fun that Happy DOM is used as I am the creator of it 🙂

I just released a new major version of Happy DOM, which I believe is causing Vitest to hang in some scenarios.

In the latest major version of Happy DOM, the Window object is a VM context. This means that global keys like Object, Array, Function etc. in the Window instance are unique to the context and will not be the same as in the global object. The change was done to solve multiple problems reported to Happy DOM.

Now when I looked at the Vitest code I noticed that the keys from the Window instance are copied to the global object. It will then override native properties (like Object, Arrray, Function etc.) with another version unique to the VM context. This will probably cause all kinds of weird behaviors.

I wish I knew that Vitest imported Happy DOM this way. I would have handled the release differently then 😅

Happy DOM now exports a class called GlobalWindow, which is meant to be executed within the global context.

To solve the problem either Vitest changes to use GlobalWindow, or Happy DOM changes Window to be the global window and creates a new window class called VMWindow (or similar).

Bug in Happy DOM:
capricorn86/happy-dom#462

Reproduction

Reproduce global reference issues

This will fail:

import { describe, expect, it } from 'vitest';

describe('suite name', () => {
    it('foo', () => {
        expect([].constructor).toBe(Array);
    });
});

Reproduce Vitest hanging
In the issue in Happy DOM several users described scenarios where just a few tests had to be run for it to happen, but I was only able to reproduce it consistently in:
https://github.com/ueberbit/lib

To reproduce:

1. git clone https://github.com/ueberbit/lib.git
2. cd ./lib
3. npm i
4. npm test

System Info

OS: Ubuntu 21.10
Vitest version: v0.10.2
Happy DOM version: v3.1.0

Used Package Manager

npm

Validations

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• The provided reproduction is a minimal reproducible example of the bug.

[sheremet-va]

Thank you very much for your reference! We saw that we had a problem with new version of happy-dom, but didn’t have time to dig in. This will surely help us fix the issues 😄

I think we can just check for GlobalWindow, and use it. If it doesn’t exist, fallback to Window. This should work with both versions, I guess?

[capricorn86]

@sheremet-va yes that should solve the issue for both versions 🙂 👍

[sheremet-va]

@capricorn86 unfortunately simple GlobalWindow || Window didn't help: #1234

Maybe you have other ideas why this might happen?

[capricorn86]

@sheremet-va I have now debugged and apparently the import of a package called "sync-request" caused the issue. Not sure what is happening, but I will make a fix for it as soon as possible in Happy DOM.

I still suggest changing to use GlobalWindow instead of Window as other problems could emerge otherwise.

[capricorn86]

There is now a fix available in the latest version of Happy DOM (v3.1.1) 🙂

[sheremet-va]

It seems, it still fails on Node 16 on Windows 🤔

https://github.com/vitest-dev/vitest/runs/6309436372?check_suite_focus=true

---

Edit: Hm, on the third rerun it passed 🤔

[capricorn86]

Weird 🤔

I only tested in the project mentioned above where it hanged and there the fix solved the problem, but I can try to debug with the test you ran as well.

[sheremet-va]

Weird 🤔

I only tested in the project mentioned above where it hanged and there the fix solved the problem, but I can try to debug with the test you ran as well.

Maybe it was just a fluke. We released the fix in 0.10.4, let's see how it will play out 😄

[capricorn86]

Yes, hopefully! 😅 It works now for the consumers that reported the problem in Happy DOM at least.