Basics

This check has a base priority of high and works with any version of Elixir.

Explanation

Requires the result of push_event/3 to be reassigned to socket rather than discarded as a statement.

push_event/3 returns a new socket with the queued event attached. If the return value is thrown away, the event never reaches the client — the call silently no-ops. The fix is always to rebind: socket = push_event(socket, ...) or to chain the call onto a pipe that propagates the socket.

The check fires on push_event calls that appear as a non-final statement in a block, with their return value discarded. Pipes ending in push_event (socket |> push_event(...)) are flagged the same way; pipes that continue past push_event to another stage (socket |> push_event(...) |> other()) are not, because the downstream stage may or may not preserve the event — we can't tell.

Bad

def handle_event("save", _, socket) do
  push_event(socket, "saved", %{})
  {:noreply, socket}
end

Good

def handle_event("save", _, socket) do
  socket = push_event(socket, "saved", %{})
  {:noreply, socket}
end

Check-Specific Parameters

There are no specific parameters for this check.

General Parameters

Like with all checks, general params can be applied.

Parameters can be configured via the .credo.exs config file.