Why Explict Invocation of Callback is Needed in setUp and tearDown?

I got to know nodeunit by reading this article http://caolanmcmahon.com/posts/unit_testing_in_node_js which should been written when nodeunit is at earlier phase. It doesn't mention that explicit invocation of callback function in setUp and tearDown.

There is no documentation about which arguments should be sent by invoking callback in setUp and tearDown. So, I suppose, in most cases, callback is just invoked without any arguments.

Why bother to require explicit invocation of this callback? can't it just be invoked by the system after setUp and tearDown is invoked?

Thanks,
-Morgan

Lisez l’article lié et comparez ses exemples de setup et de teardown avec la documentation actuelle de nodeunit. Déterminez quels arguments du callback et quel comportement d’invocation doivent être expliqués, puis documentez la justification et l’utilisation attendue ; aucun fichier ni test précis n’est nommé dans l’issue.

Rédigé par le modèle d'indexation à partir du texte de l'issue.