anonymous.ex

defmodule Plug.Anonymous do
	import Plug.Conn
  require IEx


  def init(options), do: options

  def call(conn, _opts) do

    anonymous_id = get_session(conn, "anonymous_id")
    case anonymous_id do
      nil -> put_session(conn, "anonymous_id", "Testing")
      _   -> put_session(conn, "anonymous_id", "Lovely")
    end
    # case conn.cookies do
    #   %{anonymous_id: _id}   -> conn
    #   _ -> conn |> put_resp_cookie("anonymous_id", "testing")
    # end
  end
end

anonymous_plug_test.exs

defmodule Plug.AnonymousTest do
  use ExUnit.Case, async: false
  use Plug.Test
  require IEx
  alias Plug.Anonymous

  defmodule SomeApp do
    defmodule SomeController do
      use Plug.Builder
      plug Plug.Session,
        store: :cookie,
        key: "_wankrank_key",
        signing_salt: "cmwAUEpB",
        max_age: 86400
      plug :fetch_session
      plug Anonymous
    end
  end

  test "assigns user_id session key" do
    conn = conn(:get, "/") |> SomeApp.SomeController.call([])
		refute get_session(conn, "anonymous_id") == nil
  end

  test "returns existing user session key" do
    new_conn = conn(:get, "/")
    new_conn = put_in(new_conn.secret_key_base, String.duplicate("h", 64))
    new_conn = put_in(new_conn.private, %{plug_session: %{"anonymous_id" => "some_id"}})
    new_conn = new_conn |> SomeApp.SomeController.call([])
    assert get_session(new_conn, "anonymous_id") == "some_id"
  end

  # test "raises Error if User is not provided" do
  #   # conn = conn(:get, "/") |> SomeApp.SomeController.call([])
  # end
end