Getting a ResizeObserver mock to work when testing

[grahamford]

I'm testing a couple of form input fields from the core components on a page.

The unit tests need a ResizeObserver mock to run in Jest/JSDom. I've mocked this manually in test-setup.ts and also by using the npm library resize-observer-polyfill. Both methods fix the errors about the ResizeObserver but I then get the message:

Uncaught (in promise): TypeError: 'set' on proxy: trap returned falsish for property 'disabled'
    TypeError: 'set' on proxy: trap returned falsish for property 'disabled'

Has anyone experienced the same thing, or can give me some advice on what I can do to fix this?

[mathisscott]

Can you reproduce it in a stackblitz? It seems like it may not like how this is getting set here.

A reproduction would help me validate that hunch and be much appreciated.

[grahamford]

I couldn't reproduce this in a simple StackBlitz so I created a small Nx application and included features similar to those in my real app (including the Jest configs). However I can't trigger the message about the ResizeObserver.

I created a Stackblitz here https://stackblitz.com/edit/angular-clarity5-resizeobserver?file=package.json but it won't compile. I'm guessing this is something to do with the Nx configs. There's a copy in the GitHub repo https://github.com/GrahamFord/angular-clarity5-resizeobserver if it helps.

Do you have any suggestions on what I can add to my tests that might trigger the ResizeObserver error?