'Creates a new student and enrolls that student in the course.
Adds the new user to the cls.users dictionary with the username as the key.
Returns the username once the user has been created.'

@classmethod
def create_and_enroll_student(cls, courses=None, username=None):

    if (username is not None):
        user = UserFactory.create(password=cls.test_password, username=username)
    else:
        user = UserFactory.create(password=cls.test_password)
    courses = (courses if (courses is not None) else [cls.test_course_1])
    for course in courses:
        CourseEnrollment.enroll(user, course.id, check_access=True)
    cls.users[user.username] = user
    return user.username
