LiveviewTest render_upload: key :root_pid not found in: %Phoenix.LiveViewTest.ClientProxy

[Aratramba]

Environment

• Elixir version (elixir -v): Elixir 1.18.1
• Phoenix version (mix deps): 1.7.20
• Phoenix LiveView version (mix deps): 1.0.7
• Operating system: OSX Sonoma
• Browsers you attempted to reproduce this bug on (the more the merrier): Chrome
• Does the problem persist after removing "assets/node_modules" and trying again? Yes/no: Yes

Actual behavior

I have a Liveview with a live_render'ed View inside it. The nested view has a form with an upload field. This used to work until we upgraded from Liveview 1.0.4 to 1.0.7

I think it must be related to changes from #3676

I attached two test single app files: one with Liveview 1.0.4 and the one with 1.0.7. The former passes, the latter crashes.

upload_test_case_lv1.0.4.exs.txt
upload_test_case_lv1.0.7.exs.txt

Error

This is the error:

key :root_pid not found in: %Phoenix.LiveViewTest.ClientProxy

** (exit) exited in: GenServer.call(#PID<0.478.0>, {:sync_with_root, "lv:upload-debug-nested"}, 5000)
         ** (EXIT) an exception was raised:
             ** (KeyError) key :root_pid not found in: %Phoenix.LiveViewTest.ClientProxy{
       session_token: "SFMyNTY.g2gDaAJhBnQAAAAHdwJpZG0AAAATdXBsb2FkLWRlYnVnLW5lc3RlZHcHc2Vzc2lvbnQAAAAAdwR2aWV3dyRFbGl4aXIuRXhhbXBsZS5VcGxvYWREZWJ1Z05lc3RlZExpdmV3CnBhcmVudF9waWRYdw1ub25vZGVAbm9ob3N0AAAB3wAAAAAAAAAAdwlyb290X3ZpZXd3F0VsaXhpci5FeGFtcGxlLkhvbWVMaXZldwZyb3V0ZXJ3FUVsaXhpci5FeGFtcGxlLlJvdXRlcncIcm9vdF9waWRYdw1ub25vZGVAbm9ob3N0AAAB3wAAAAAAAAAAbgYAA4mv0pUBYgABUYA.SDO68nteWqaaJXld2gjkVjjYsrnvvxBaR8Onhk7RjkM",
       static_token: "SFMyNTY.g2gDaAJhBnQAAAADdwJpZG0AAAATdXBsb2FkLWRlYnVnLW5lc3RlZHcKYXNzaWduX25ld2p3BWZsYXNodAAAAABuBgDriK_SlQFiAAFRgA.Q_2uXqoM_sUVtFC_5sjbeTYDrl5dVnfl1SHkT9gEOl0",
       module: Example.UploadDebugNestedLive,
       endpoint: Example.Endpoint,
       router: nil,
       pid: #PID<0.480.0>,
       proxy: #PID<0.478.0>,
       topic: "lv:upload-debug-nested",
       ref: #Reference<0.2560702666.3450339331.178198>,
       rendered: %{
         0 => %{
           0 => " id=\"phx-GDBeDvR2_M0ciRMj\"",
           1 => " name=\"avatar\"",
           2 => " accept=\".jpg,.jpeg,.png\"",
           3 => " data-phx-upload-ref=\"phx-GDBeDvR2_M0ciRMj\"",
           4 => " data-phx-active-refs=\"4932\"",
           5 => " data-phx-done-refs=\"4932\"",
           6 => " data-phx-preflighted-refs=\"4932\"",
           7 => "",
           8 => " multiple",
           :s => ["<input", " type=\"file\"", "",
            " data-phx-hook=\"Phoenix.LiveFileUpload\" data-phx-update=\"ignore\"",
            "", "", "", "", "", ">"],
           :r => 1
         },
         :s => ["<form id=\"upload-form\" phx-submit=\"save\" phx-change=\"validate\">\n  ",
          "\n  <button type=\"submit\">Upload</button>\n</form>"],
         :r => 1,
         :streams => []
       },
       children: [],
       child_statics: %{},
       id: "upload-debug-nested",
       uri: nil,
       connect_params: %{},
       connect_info: %{},
       on_error: :warn
     }
                 (phoenix_live_view 1.0.7) lib/phoenix_live_view/test/client_proxy.ex:609: anonymous fn/2 in Phoenix.LiveViewTest.ClientProxy.handle_call/3
                 (stdlib 6.0) gen_server.erl:2209: :gen_server.try_handle_call/4
                 (stdlib 6.0) gen_server.erl:2238: :gen_server.handle_msg/6
                 (stdlib 6.0) proc_lib.erl:329: :proc_lib.init_p_do_apply/3

Reduced test case:

See the attached file for a single file app.

defmodule LiveviewSandboxWeb.UploadDebugLive do
  use LiveviewSandboxWeb, :live_view

  def mount(_params, _session, socket) do
    {:ok, socket}
  end

  def render(assigns) do
    ~H"""
    {live_render(@socket, LiveviewSandboxWeb.UploadDebugNestedLive,
      id: "upload-debug-nested",
      session: %{}
    )}
    """
  end
end

defmodule LiveviewSandboxWeb.UploadDebugNestedLive do
  use LiveviewSandboxWeb, :live_view

  @impl Phoenix.LiveView
  def mount(_params, _session, socket) do
    {:ok,
     socket
     |> assign(:uploaded_files, [])
     |> allow_upload(:avatar, accept: ~w(.jpg .jpeg .png), max_entries: 2)}
  end

  @impl Phoenix.LiveView
  def render(assigns) do
    ~H"""
    <form id="upload-form" phx-submit="save" phx-change="validate">
      <.live_file_input upload={@uploads.avatar} />
      <button type="submit">Upload</button>
    </form>
    """
  end

  @impl Phoenix.LiveView
  def handle_event("validate", _params, socket) do
    {:noreply, socket}
  end

  @impl Phoenix.LiveView
  def handle_event("cancel-upload", %{"ref" => ref}, socket) do
    {:noreply, cancel_upload(socket, :avatar, ref)}
  end

  @impl Phoenix.LiveView
  def handle_event("save", _params, socket) do
    uploaded_files =
      consume_uploaded_entries(socket, :avatar, fn %{path: path}, _entry ->
        dest =
          Path.join([:code.priv_dir(:liveview_sandbox), "static", "uploads", Path.basename(path)])

        File.cp!(path, dest)
        {:ok, "/uploads/#{Path.basename(dest)}"}
      end)

    {:noreply, update(socket, :uploaded_files, &(&1 ++ uploaded_files))}
  end
end

defmodule LiveviewSandboxWeb.UploadDebugNestedLiveTest do
  use LiveviewSandboxWeb.ConnCase, async: false
  import Phoenix.LiveViewTest

  test "uploading a file", %{conn: conn} do
    {:ok, view, _html} = live(conn, "/upload-debug")

    [nested_view] = live_children(view)

    avatar =
      file_input(nested_view, "#upload-form", :avatar, [
        %{
          name: "red-dot.png",
          content: File.read!("test/data/red-dot.png"),
          type: "image/png"
        }
      ])

    render_upload(avatar, "red-dot.png")
  end
end

Expected behavior

I expect the test not to crash.

[SteffenDE]

Sorry for the inconvenience. The fix will be included in the next release!