TL;DR: I'm not a huge fan of extensive unit tests for rendered HTML. Despite that, I've put a fair amount of work into some test support code for Phoenix views. Mostly, that was because I thought it would be a good learning experience for me, a novice in Phoenix and Elixir. But I came up with some testing conventions and code that might be useful to others. They might also serve as a model for testing other complex data structures.
Why don't I like automated tests for views?
Nowadays, it's usually very quick to visually check a change.