:lv_event — removes Phoenix.LiveView.push_event/3,4, which sends a
server-initiated event to the client's handleEvent JS hook
(push_event(socket, "highlight", %{id: 1}), optionally with trailing options such as
dispatch: :before):
push_event(socket, event, payload) -> socket
push_event(socket, event, payload, opts) -> socket
socket |> push_event(event, payload) -> socketA piped stage is removed with everything upstream of it kept: the report diffs
socket |> push_event(...) against socket.
A survivor means no test asserts the event reaches the client.
Phoenix.LiveViewTest.assert_push_event/3 is the assertion that kills it.