public void VerifyScores()
{
GradeBook gbook = new GradeBook();
gbook.AddGrade(20);
gbook.AddGrade(40);
gbook.AddGrade(60);
gbook.AddGrade(70);
GradeBook newBook = new GradeBook();
gbook.IncrementScore();
gbook.CalculateTotalScore();
Assert.AreNotEqual(gbook.TotalScore, newBook.TotalScore);
newBook.IncrementScore();
newBook.CalculateTotalScore();
Assert.AreEqual(gbook.TotalScore, newBook.TotalScore);
}