Test on checking value with null constraint error

So I have a School model that has a required attribute student (from model Student). Somewhere in my serializer I do the following:

@staticmethod
def get_student_name(school):
    if school.student:
        return school.student.name
    return "no name"

Now, a student can of course not be none or empty, ideally. But I do want to have the test if it's none to avoid errors (if there are mistakes in the database or..)

So I want to write a test to go over these checks (to have a full 100% coverage). But when I try to create a School model in my test class, I, ofcourse, get a Null constraint error

Is there a way to test this so I return "no name" for a student name if he doesn't have one instead of an error?