Maybe a bit pedantic, but does manual testing really need to be done, or is the intent here more towards being a usability review? I can't think of any time obvious unintended behaviour showed up not caught by the contract encoded in tests (there is no reason to write code that doesn't have a contractual purpose), but, after trying it, finding out that what you've created has an awful UX is something I have encountered and that is something much harder to encode in tests[1].

[1] As far as I can tell. If there are good solutions for this too, I'd love to learn.