Show logout template after logging out

lib/livebook/config.ex

@@ -278,7 +278,7 @@ defmodule Livebook.Config do
     identity_logout? =
       Code.ensure_loaded?(module) and function_exported?(module, :logout, 2)
 
-    authentication().mode != :disabled or identity_logout?
+    identity_logout?
   end
 
   @doc """

lib/livebook_web/controllers/auth_controller.ex

@@ -1,13 +1,14 @@
 defmodule LivebookWeb.AuthController do
   use LivebookWeb, :controller
+  alias LivebookWeb.AuthHelpers
 
   plug(:require_unauthenticated)
 
   alias LivebookWeb.AuthPlug
 
   defp require_unauthenticated(conn, _opts) do
     if AuthPlug.authenticated?(conn) do
-      redirect_to(conn)
+      AuthHelpers.redirect_to(conn)
     else
       conn
     end
@@ -30,7 +31,7 @@ defmodule LivebookWeb.AuthController do
     conn = AuthPlug.store(conn, :password, password)
 
     if AuthPlug.authenticated?(conn) do
-      redirect_to(conn)
+      AuthHelpers.redirect_to(conn)
     else
       render_form_error(conn, :password)
     end
@@ -40,23 +41,12 @@ defmodule LivebookWeb.AuthController do
     conn = AuthPlug.store(conn, :token, token)
 
     if AuthPlug.authenticated?(conn) do
-      redirect_to(conn)
+      AuthHelpers.redirect_to(conn)
     else
       render_form_error(conn, :token)
     end
   end
 
-  def logout(conn, _params) do
-    if get_session(conn, :user_id) do
-      conn
-      |> configure_session(renew: true)
-      |> clear_session()
-      |> render("logout.html")
-    else
-      redirect_to(conn)
-    end
-  end
-
   defp render_form_error(conn, authentication_mode) do
     errors = [{"%{authentication_mode} is invalid", [authentication_mode: authentication_mode]}]
 
@@ -65,18 +55,4 @@ defmodule LivebookWeb.AuthController do
       authentication_mode: authentication_mode
     )
   end
-
-  defp redirect_to(conn) do
-    conn
-    |> then(fn conn ->
-      if redirect_to = get_session(conn, :redirect_to) do
-        conn
-        |> delete_session(:redirect_to)
-        |> redirect(to: redirect_to)
-      else
-        redirect(conn, to: ~p"/")
-      end
-    end)
-    |> halt()
-  end
 end

lib/livebook_web/controllers/auth_helpers.ex

@@ -0,0 +1,17 @@
+defmodule LivebookWeb.AuthHelpers do
+  use LivebookWeb, :controller
+
+  def redirect_to(conn) do
+    conn
+    |> then(fn conn ->
+      if redirect_to = get_session(conn, :redirect_to) do
+        conn
+        |> delete_session(:redirect_to)
+        |> redirect(to: redirect_to)
+      else
+        redirect(conn, to: ~p"/")
+      end
+    end)
+    |> halt()
+  end
+end

lib/livebook_web/controllers/user_auth_controller.ex

@@ -0,0 +1,15 @@
+defmodule LivebookWeb.UserAuthController do
+  use LivebookWeb, :controller
+  alias LivebookWeb.AuthHelpers
+
+  def logout(conn, _params) do
+    if get_session(conn, :user_id) do
+      conn
+      |> configure_session(renew: true)
+      |> clear_session()
+      |> render("logout.html")
+    else
+      AuthHelpers.redirect_to(conn)
+    end
+  end
+end

lib/livebook_web/controllers/user_auth_html.ex

@@ -0,0 +1,5 @@
+defmodule LivebookWeb.UserAuthHTML do
+  use LivebookWeb, :html
+
+  embed_templates "user_auth_html/*"
+end

lib/livebook_web/router.ex

@@ -171,7 +171,7 @@ defmodule LivebookWeb.Router do
 
   scope "/", LivebookWeb do
     pipe_through [:browser]
-    get "/logout", AuthController, :logout
+    get "/logout", UserAuthController, :logout
   end
 
   defp within_iframe_secure_headers(conn, _opts) do

test/livebook_web/controllers/user_auth_controller_test.exs

@@ -0,0 +1,29 @@
+defmodule LivebookWeb.UserAuthControllerTest do
+  use LivebookWeb.ConnCase, async: true
+
+  describe "GET /logout" do
+    test "renders logout template when logged in", %{conn: conn} do
+      conn = login_user(conn)
+
+      conn = get(conn, ~p"/logout")
+
+      assert html_response(conn, 200) =~ "You have been logged out"
+    end
+
+    test "redirects when already logged out", %{conn: conn} do
+      conn = logout_user(conn)
+
+      conn = get(conn, ~p"/logout")
+
+      assert redirected_to(conn) == ~p"/"
+    end
+
+    defp login_user(conn) do
+      Phoenix.ConnTest.init_test_session(conn, %{user_id: 1})
+    end
+
+    defp logout_user(conn) do
+      Phoenix.ConnTest.init_test_session(conn, %{})
+    end
+  end
+end