private void When(TeacherAddedDomainEvent domainEvent)
{
teachers = teachers ?? new List <Teacher>();
Teacher teacher = Teacher.Create(domainEvent.TeacherId, domainEvent.TeacherName);
teachers.Add(teacher);
}
public void AddTeacher(Teacher teacher)
{
Raise(TeacherAddedDomainEvent.Create(this, teacher.Id, teacher.GetName()));
}