public void AddTeacherTest()
{
ISchoolService service = new SchoolService();
List <Teacher> teachers = service.GetAllTeachers();
int count = teachers.Count;
service.AddTeacher(new Teacher {
Id = 123, Name = "Zimba"
});
teachers = service.GetAllTeachers();
int newCount = teachers.Count;
Assert.AreEqual(count + 1, newCount);
}