Crash at (floki 0.37.0) lib/floki/finder.ex:56: Floki.Finder.find/2

[mellelieuwes]

Description

Error in Phoenix Live View test code. The error:

16:43:41.594 [error] GenServer #PID<0.1169.0> terminating
** (MatchError) no match of right hand side value: []
(floki 0.37.0) lib/floki/finder.ex:56: Floki.Finder.find/2
(phoenix_live_view 1.0.0) lib/phoenix_live_view/test/dom.ex:70: Phoenix.LiveViewTest.DOM.targets_from_selector/2
(phoenix_live_view 1.0.0) lib/phoenix_live_view/test/client_proxy.ex:1063: anonymous fn/6 in Phoenix.LiveViewTest.ClientProxy.maybe_js_commands/6
(elixir 1.17.0) lib/enum.ex:4353: Enum.flat_map_list/2
(phoenix_live_view 1.0.0) lib/phoenix_live_view/test/client_proxy.ex:321: Phoenix.LiveViewTest.ClientProxy.handle_info/2
(stdlib 6.1.2) gen_server.erl:2345: :gen_server.try_handle_info/3
(stdlib 6.1.2) gen_server.erl:2433: :gen_server.handle_msg/6
(stdlib 6.1.2) proc_lib.erl:329: :proc_lib.init_p_do_apply/3
Last message: {:EXIT, #PID<0.1124.0>, {{:badmatch, []}, [{Floki.Finder, :find, 2, [file: ~c"lib/floki/finder.ex", line: 56]}, {Phoenix.LiveViewTest.DOM, :targets_from_selector, 2, [file: ~c"lib/phoenix_live_view/test/dom.ex", line: 70]}, {Phoenix.LiveViewTest.ClientProxy, :"-maybe_js_commands/6-fun-1-", 6, [file: ~c"lib/phoenix_live_view/test/client_proxy.ex", line: 1063]}, {Enum, :flat_map_list, 2, [file: ~c"lib/enum.ex", line: 4353]}, {Phoenix.LiveViewTest.ClientProxy, :handle_info, 2, [file: ~c"lib/phoenix_live_view/test/client_proxy.ex", line: 321]}, {:gen_server, :try_handle_info, 3, [file: ~c"gen_server.erl", line: 2345]}, {:gen_server, :handle_msg, 6, [file: ~c"gen_server.erl", line: 2433]}, {:proc_lib, :init_p_do_apply, 3, [file: ~c"proc_lib.erl", line: 329]}]}}

Cause

 def find(html_tree_as_tuple, selectors)
      when (is_list(html_tree_as_tuple) or is_html_node(html_tree_as_tuple)) and
             is_list(selectors) do
    if traverse_html_tuples?(selectors) do
      [selector] = selectors
      html_tree_as_tuple = List.wrap(html_tree_as_tuple)
      results = traverse_html_tuples(html_tree_as_tuple, selector, [])
      Enum.reverse(results)
    else
      tree = HTMLTree.build(html_tree_as_tuple)
      results = find(tree, selectors)
      Enum.map(results, fn html_node -> HTMLTree.to_tuple(tree, html_node) end)
    end
  end

On line 55 traverse_html_tuples?(selectors) can result in true while selectors list is empty due to this line:

defp traverse_html_tuples?([]), do: true

This results in a no match of right hand side value: [] error on line 56:

[selector] = selectors

Possible fix

Return false when selector list is empty:
defp traverse_html_tuples?([]), do: false

Phoenix Live View test code

    test "a valid token activates the account", %{conn: conn} do
      user = Factories.insert!(:member, %{confirmed_at: nil})

      token =
        extract_user_token(fn url ->
          Account.Public.deliver_user_confirmation_instructions(user, url)
        end)

      {:ok, view, _html} = live(conn, ~p"/user/confirm/#{token}")

      {:error, {:redirect, %{to: to}}} =
        view
        |> element("[phx-click=\"confirm\"]")
        |> render_click()

      assert to == "/user/signin?#{URI.encode_query(%{email: user.email})}"
      assert Account.Public.get_user!(user.id).confirmed_at
    end