public static CoursesCounter Random()
        {
            var existingCourses = ListMother <CourseId> .Random(CourseIdMother.Random);

            return(Create(
                       CoursesCounterIdMother.Random(),
                       CoursesCounterTotalMother.Create(existingCourses.Count),
                       existingCourses
                       ));
        }
 public static CoursesCounter WithOne(CourseId courseId)
 {
     return(Create(CoursesCounterIdMother.Random(), CoursesCounterTotalMother.One(),
                   ListMother <CourseId> .One(courseId)));
 }