tests: add more integration tests for core tools.

tests/bats/sync.bats

@@ -0,0 +1,22 @@
+#!/usr/bin/env bats
+# apparmor.d - Full set of apparmor profiles
+# Copyright (C) 2024 Alexandre Pujol <alexandre@pujol.io>
+# SPDX-License-Identifier: GPL-2.0-only
+
+load common
+
+setup_file() {
+    aa_setup
+}
+
+# bats test_tags=sync
+@test "sync: Flush all pending write operations on all disks" {
+    sync
+    aa_check
+}
+
+# bats test_tags=sync
+@test "sync: Flush all pending write operations on a single file to disk" {
+    sudo sync /
+    aa_check
+}