UnitTesting Mixins and ClassBasedViews

I am using pytest to write my tests - well I try to test my app. I am relative new to the topic.
I wrote a mixing that specializes the UserPassesTestMixin:

class UserInMyGroupMixin(UserPassesTestMixin):
    def test_func(self):
        return self.request.user.groups.filter(name="MyGroup").exists()

now Coverage tells me that I have to test it. But how?
It also tells me that I have to test:

def get_context_data(self, **kwargs): 
     context = super().get_context_data(**kwargs) 
     context["object_type"] = "Schulung" 
     return context 

def get_success_url(self): 
    return reverse("schulungen:list")

of my DetailView. Should I just instanciate the Classes and then call the functions? Or how would I test their methods?