gio/tests: Add tests for flatpak infos

Support testing flatpak infos, we do it by faking /.flatpak-info file in
case we're building in test mode.

gio/tests/portal-support-flatpak-none.c

@@ -0,0 +1,47 @@
+/*
+ * GIO - GLib Input, Output and Streaming Library
+ *
+ * Copyright (C) 2022 Canonical Ltd.
+ *
+ * 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: Marco Trevisan <marco.trevisan@canonical.com>
+ */
+
+#include "portal-support-utils.h"
+
+#include "../gportalsupport.h"
+#include <gio/gio.h>
+
+static void
+test_portal_support_flatpak_none (void)
+{
+  create_fake_flatpak_info (g_get_user_runtime_dir (), NULL, NULL);
+
+  g_assert_true (glib_should_use_portal ());
+  g_assert_false (glib_network_available_in_sandbox ());
+  g_assert_false (glib_has_dconf_access_in_sandbox ());
+}
+
+int
+main (int argc, char **argv)
+{
+  g_test_init (&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
+
+  g_test_add_func ("/portal-support/flatpak/none", test_portal_support_flatpak_none);
+
+  return g_test_run ();
+}