Hi, super late response here but I was looking for the same thing and this was the first post that came up. In my case it wasn’t even Javascript- I just wanted to test contents inside a <details> tag.
So this kind of thing can’t be tested in Phoenix (see Testing LiveView with JS Commands - #2 by sodapopcan). All of the helpers (eg render_click) are triggering server-side changes in Liveview. If your change requires some client-side handling, it can’t be tested.
