how to test animations

Hi,
I'm using StaggeredMotion and spring to create a basic animation, and I'm trying to implement automated tests to check the animation is running as expected when triggered, however I can't figure out how to correctly implement this.

The idea is doing something like this:

```
describe('test animation', () => {
let clock;

beforeEach(() => {
clock = sinon.useFakeTimers();
})

afterEach(() => {
clock.restore();
});

it('animation should progress', () => {
[...]
clock.tick(200);
// check the state of some nodes here
[...]
});
});
```

But this doesn't seem to work as expected (I'm using a `create-react-app` environment), so I think I'm missing something important. Sorry if the question is dummy but I couldn't find examples about achieving this. I would appreciate if anyone could help ?

Start by reproducing the StaggeredMotion and spring example in the create-react-app environment described, using Sinon fake timers as shown. Check how animation updates are scheduled and determine what a working automated test must observe after advancing the clock. Done means documenting a reliable testing approach with a representative example.

Written by the indexing model from the issue text.