public void AddStudent()
        {
            var numberOfDays = DateTimeRange.CreateOneWeekRange(DateTime.Now);
            var maxCapacity  = new Capacity(20);
            var instructorId = Guid.NewGuid();
            var students     = Enumerable.Empty <StudentDM>();
            var course       = CourseDM.CreateCourse("Computer", numberOfDays, maxCapacity, instructorId, students);

            course.AddStudent(new StudentDM(Guid.NewGuid(), "John", "Adam"));

            course.Students.Count.Should().BeGreaterThan(0);
        }
        public void CreateCourse()
        {
            var numberOfDays = DateTimeRange.CreateOneWeekRange(DateTime.Now);
            var maxCapacity  = new Capacity(20);
            var instructorId = Guid.NewGuid();
            var students     = new[]
            {
                new StudentDM(Guid.NewGuid(), "John", "Adam"),
                new StudentDM(Guid.NewGuid(), "Marry", "Smith")
            };
            var course = CourseDM.CreateCourse("Computer", numberOfDays, maxCapacity, instructorId, students);

            course.Should().NotBeNull();
        }