From 6061901ee9a954f84f0243d7eefbc63269e66848 Mon Sep 17 00:00:00 2001
From: ByeongUk Choi <cbw0916@gmail.com>
Date: Mon, 8 May 2023 18:26:21 +0900
Subject: [PATCH] Add info about empty Kino outputs (#1899)

---
 lib/livebook_web/live/app_live.ex        |  4 +++
 test/livebook_web/live/app_live_test.exs | 34 ++++++++++++++++++++++++
 2 files changed, 38 insertions(+)
 create mode 100644 test/livebook_web/live/app_live_test.exs

diff --git a/lib/livebook_web/live/app_live.ex b/lib/livebook_web/live/app_live.ex
index ecd409a45..8305739c5 100644
--- a/lib/livebook_web/live/app_live.ex
+++ b/lib/livebook_web/live/app_live.ex
@@ -119,6 +119,10 @@ defmodule LivebookWeb.AppLive do
               input_values={output_view.input_values}
             />
           </div>
+          <div :if={@data_view.output_views == []} class="info-box">
+            This deployed notebook is empty. Deployed apps only render Kino outputs.
+            Ensure you use Kino for interactive visualizations and dynamic content.
+          </div>
         </div>
         <div style="height: 80vh"></div>
       </div>
diff --git a/test/livebook_web/live/app_live_test.exs b/test/livebook_web/live/app_live_test.exs
new file mode 100644
index 000000000..68b8c32ed
--- /dev/null
+++ b/test/livebook_web/live/app_live_test.exs
@@ -0,0 +1,34 @@
+defmodule LivebookWeb.AppLiveTest do
+  use LivebookWeb.ConnCase, async: true
+
+  import Phoenix.LiveViewTest
+
+  alias Livebook.Session
+
+  test "render guidance when Kino output is empty", %{conn: conn} do
+    session = start_session()
+
+    Session.subscribe(session.id)
+
+    slug = Livebook.Utils.random_short_id()
+    app_settings = %{Livebook.Notebook.AppSettings.new() | slug: slug}
+    Session.set_app_settings(session.pid, app_settings)
+
+    Session.set_notebook_name(session.pid, "My app #{slug}")
+    Session.deploy_app(session.pid)
+
+    assert_receive {:operation, {:add_app, _, _, _}}
+    assert_receive {:operation, {:set_app_registered, _, _, true}}
+
+    {:ok, view, _} = live(conn, ~p"/apps/#{slug}")
+
+    assert render(view) =~
+             "This deployed notebook is empty. Deployed apps only render Kino outputs."
+  end
+
+  defp start_session() do
+    {:ok, session} = Livebook.Sessions.create_session()
+    on_exit(fn -> Session.close(session.pid) end)
+    session
+  end
+end