iFrames and their parent pages have two separate HTML DOMs (document-object models), so it takes some extra work to write tests that can reliably interact with both sets of elements. Extra work that we do all the time.
Test how other websites, videos, maps, or social media posts render and perform, including multiple breakpoints.
iframes are a great way to have different content load at different times, and we can test how that everything's coming in as intended.
If you use an iframe for SSO, we test that a user can log into multiple systems with a single set of credentials.