#10818 has added integration tests for scrollbound and visibilit-based amp-animations however we need to find a way to test in in-a-box and FIE cases.

There reasons this is tricky is:
1- we need to scroll the top page but observe an element inside the 3p iframe
2- we need to measure the calculated opacity for an element that's inside an iframe which we do not have direct access to.
One solution is postMessage but that's not really a true integration tests as the a4a creative is not valid if it runs JS.
Another crazy idea is using CSS blending by overlaying an element (which lives in the parent) that blends differently based on opacity of the item in the iframe and measure that instead!