How to test my logic in a signal method?

Using Django
1

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 models.py and I need to test the logic.
How can I do that?

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

Thank you!