def METHOD_NAME(self):
    """
    Test that we get an updated score of 0, and not a ZeroDivisionError,
    when dealing with an invalid score like 0/0.
    """
    # This will create a PersistentSubsectionGrade with a score of 0/0.
    with mock_get_score(0, 0):
        grade = self.subsection_grade_factory.update(self.sequence)
    self.assert_grade(grade, 0, 0)
    # Ensure that previously storing a possible score of 0
    # does not raise a ZeroDivisionError when updating the grade.
    with mock_get_score(2, 2):
        grade = self.subsection_grade_factory.update(self.sequence, only_if_higher=True)
    self.assert_grade(grade, 2, 2)