Add sudo mode acceptance tests, per #8210 feedback

[LawnGnome]

Whichever stage of sudo grief we're at, we're now at acceptance.

I don't think there's anything surprising here. I used the yank button as a proxy for the general PrivilegedAction functionality rather than creating a new test-only component, since it's already on main and is unlikely to change significantly. Unit tests are covering all the actually interesting bits anyway.

The one thing that I was surprised by is that the qunit-dom helpers were capable of clicking a button in a disabled fieldset, even though that's not possible from the browser UI, which means I can't write a sensible "failed to yank" style test. (I tried a few different ways just to be sure.)

[Turbo87]

The one thing that I was surprised by is that the qunit-dom helpers were capable of clicking a button in a disabled fieldset

The click() fn comes from https://github.com/emberjs/ember-test-helpers, not qunit-dom, which only deals with DOM state assertions.

https://github.com/emberjs/ember-test-helpers/blob/master/addon/addon-test-support/%40ember/test-helpers/dom/click.ts is the implementation of click(), which emulates the native events that the browser would fire when a users clicks a button. But admittedly https://github.com/emberjs/ember-test-helpers/blob/9cec68dc6aa9c0a7a449eb89797eb81299fa727f/addon/addon-test-support/%40ember/test-helpers/dom/click.ts#L116-L118 only checks if the element itself is disabled, but does not care about parent fieldsets or forms.

[Turbo87]

LGTM 👍

we might want an additional test though that checks that the sudo mode controls are invisible when the user is not an admin

[LawnGnome]

we might want an additional test though that checks that the sudo mode controls are invisible when the user is not an admin

Good call; added.