The good method for completion for alias in this web https://ubuntuforums.org/showthread.php?t=733397.
Now in 16.04, seems rules changed.
I can not find apt(_apt) completion command. but ls is(_longopt) here and it can works. of course apt also not in /etc/bash_completion.d/.
▶ complete |grep apt ▶ complete |grep '\<ls\>' complete -F _longopt ls ▶ complete |grep 'upstart' complete -F _upstart_reload reload complete -F _upstart_stop stop complete -F _upstart_initctl initctl complete -F _upstart_start start complete -F _upstart_status status complete -F _upstart_restart restart