tests: Add stub tests for GFdoNotificationBackend

This test is fairly pointless, but puts the infrastructure in place for
adding more tests for `GFdoNotificationBackend` in upcoming commits.

Signed-off-by: Philip Withnall <pwithnall@endlessos.org>

Helps: #1904

gio/tests/fdo-notification-backend.c

@@ -0,0 +1,103 @@
+/*
+ * Copyright © 2022 Endless OS Foundation, LLC
+ *
+ * SPDX-License-Identifier: LGPL-2.1-or-later
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General
+ * Public License along with this library; if not, see <http://www.gnu.org/licenses/>.
+ *
+ * Author: Philip Withnall <pwithnall@endlessos.org>
+ */
+
+#include <gio/gio.h>
+#include <locale.h>
+
+#include <gio/giomodule-priv.h>
+#include "gio/gnotificationbackend.h"
+
+
+static GNotificationBackend *
+construct_backend (GApplication **app_out)
+{
+  GApplication *app = NULL;
+  GType fdo_type = G_TYPE_INVALID;
+  GNotificationBackend *backend = NULL;
+  GError *local_error = NULL;
+
+  /* Construct the app first and withdraw a notification, to ensure that IO modules are loaded. */
+  app = g_application_new ("org.gtk.TestApplication", G_APPLICATION_DEFAULT_FLAGS);
+  g_application_register (app, NULL, &local_error);
+  g_assert_no_error (local_error);
+  g_application_withdraw_notification (app, "org.gtk.TestApplication.NonexistentNotification");
+
+  fdo_type = g_type_from_name ("GFdoNotificationBackend");
+  g_assert_cmpuint (fdo_type, !=, G_TYPE_INVALID);
+
+  /* Replicate the behaviour from g_notification_backend_new_default(), which is
+   * not exported publicly so can‘t be easily used in the test. */
+  backend = g_object_new (fdo_type, NULL);
+  backend->application = app;
+  backend->dbus_connection = g_application_get_dbus_connection (app);
+  if (backend->dbus_connection)
+    g_object_ref (backend->dbus_connection);
+
+  if (app_out != NULL)
+    *app_out = g_object_ref (app);
+
+  g_clear_object (&app);
+
+  return g_steal_pointer (&backend);
+}
+
+static void
+test_construction (void)
+{
+  GNotificationBackend *backend = NULL;
+  GApplication *app = NULL;
+  GTestDBus *bus = NULL;
+
+  g_test_message ("Test constructing a GFdoNotificationBackend");
+
+  /* Set up a test session bus and connection. */
+  bus = g_test_dbus_new (G_TEST_DBUS_NONE);
+  g_test_dbus_up (bus);
+
+  backend = construct_backend (&app);
+  g_assert_nonnull (backend);
+
+  g_application_quit (app);
+  g_clear_object (&app);
+  g_clear_object (&backend);
+
+  g_test_dbus_down (bus);
+  g_clear_object (&bus);
+}
+
+int
+main (int   argc,
+      char *argv[])
+{
+  setlocale (LC_ALL, "");
+
+  /* Force use of the FDO backend */
+  g_setenv ("GNOTIFICATION_BACKEND", "freedesktop", TRUE);
+
+  g_test_init (&argc, &argv, NULL);
+
+  /* Make sure we don’t send notifications to the actual D-Bus session. */
+  g_test_dbus_unset ();
+
+  g_test_add_func ("/fdo-notification-backend/construction", test_construction);
+
+  return g_test_run ();
+}

gio/tests/meson.build

@@ -405,6 +405,7 @@ if host_machine.system() != 'windows'
         'extra_sources' : extra_sources,
         'suite' : ['slow'],
       },
+      'fdo-notification-backend': {},
       'gdbus-auth' : {'extra_sources' : extra_sources},
       'gdbus-bz627724' : {'extra_sources' : extra_sources},
       'gdbus-close-pending' : {'extra_sources' : extra_sources},