Types are there to ensure against human error and reduce the amount of code we need to write.

Tests exist to guarantee functionality and increase productivity (by ensuring intended functionality remains as we refactor/change our code/UI).

There may be cases where some tests are too expensive to write, but I have never come across this myself. For example, in functional tests you would attempt to find a secure way to distinguish elements regardless of future changes to that UI. If your UI changes so much between iterations that this is impossible it sounds like you need to consider the layout a little more before building anything. I’m saying that based on experience, having been involved in several projects where this was a problem.

Having said that, I’m myself horrible at writing tests for UI, an area I’m trying to improve myself, it really bothers me :)