Avoid django asking 'You don't have any superusers defined...' during tests

When I run tests, Django is always asking:

You have installed Django's auth system, and don't have any superusers defined. Would you like to create one now? (yes/no):

I dont want to create it. I dont want Django to ask. The obvious action to do is remove 'django.contrib.auth', from INSTALLED_APPS. But I cant because I need it to my set of tests. Im using sqlite3 as DB.

Thank you.