How to test my logic in a signal method?

Hello, Guys!
I’m a little bit stuck on how I write a unit test for my logic in a signal method!

Here is my method and I put it in and I need to test the logic.
How can I do that?

def user_signed_up_(request, user, **kwargs):
    s = Avatar.generate(128,, "PNG")'%s.png' % ([0] + str(, ContentFile(s))
    user.is_active = True

Thank you!