mmm yes it's the body when nothing is focussed..

You can do:
```javascript
// in setup
Object.defineProperty(document, 'activeElement', {
  value: <XXX>,
  configurable: true, // I think it's necessary to be able to delete it
  enumerable: true,
  writable: true // if you set this to true, you'll be able to change the value in tests
});

// in teardown
delete document.activeElement;
```

this works because the "real" activeElement is not on "document" but on a prototype, as you can check with `Object.getOwnPropertyDescriptor(Object.getPrototypeOf(Object.getPrototypeOf(document)), 'activeElement')`

Now, is it really worth the trouble ? Maybe not. So maybe try it but if you can't make it work in 30 minutes let's forget it. Also if you _can_ make it work, have a look to decide if it's meaningful enough... maybe it's not?