Yeah there's no silver bullet for any of these problems probably. That said an end-to-end test seems just as likely to merely test implementation details. You

Yeah there's no silver bullet for any of these problems probably. That said an end-to-end test seems just as likely to merely test implementation details. You could have all kinds of changes in behaviour without necessarily doing anything incorrect. I suppose the point is that you need to test where you can define what correct behaviour is. And if this is only possible for end-to-end tests then something is screwy.