public void BookReturnsAverageGrade() { // arrange var book = new InMemoryBook("Test Book"); book.AddGrade(99.9); book.AddGrade(49.3); book.AddGrade(39.3); book.AddGrade(29.3); book.AddGrade(19.3); var expected = 47.42; // act var actual = book.GetGradeAverage(); // assert Assert.Equal(actual, expected); }