tests: add a few integration tests.

tests/integration/procps/uptime.bats

@@ -0,0 +1,18 @@
+#!/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
+
+@test "uptime: Print current time, uptime, number of logged-in users and other information" {
+    uptime
+}
+
+@test "uptime: Show only the amount of time the system has been booted for" {
+    uptime --pretty
+}
+
+@test "uptime: Print the date and time the system booted up at" {
+    uptime --since
+}