test: add initial structure for the common integration tests.

- Add bats common helpers.
- Add a first set of tests for some simple program.

tests/bats/ps.bats

@@ -0,0 +1,46 @@
+#!/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=ps
+@test "ps: List all running processes" {
+    ps aux
+    aa_check
+}
+
+# bats test_tags=ps
+@test "ps: List all running processes including the full command string" {
+    ps auxww
+    aa_check
+}
+
+# bats test_tags=ps
+@test "ps: List all processes of the current user in extra full format" {
+    ps --user "$(id -u)" -F
+    aa_check
+}
+
+# bats test_tags=ps
+@test "ps: List all processes of the current user as a tree" {
+    ps --user "$(id -u)" -f
+    aa_check
+}
+
+# bats test_tags=ps
+@test "ps: Get the parent PID of a process" {
+    ps -o ppid= -p 1
+    aa_check
+}
+
+# bats test_tags=ps
+@test "ps: Sort processes by memory consumption" {
+    ps auxww --sort size
+    aa_check
+}