public void TestCourseRemoveStudentIfIncorrectRemoval()
 {
     Course course = new Course("Maths");
     course.Students.Add(new Student("Petyr", 10002));
     course.Students.Add(new Student("Nikola", 10003));
     course.RemoveStudentByNumber(10004);
     Assert.AreEqual(2, course.Students.Count, 
         "The students changes but not expected");
 }
 public void TestCourseRemoveStudentIfCountLessThan1()
 {
     Course course = new Course("Maths");
     course.RemoveStudentByNumber(22);
 }