public void GradeBook_AddGrade_AddsGradeToGradesList()
        {
            var book = new InMemoryGradeBook("test");

            book.AddGrade(30.0);

            var expected = 30.0;
            var actual   = book.GetGradeBookStatistics().Average;

            Assert.Equal(expected, actual);
        }
        public void GradeBook_GetGradeBookStatistics_CalculatesStatsFromGradeBookList()
        {
            // Arrange
            InMemoryGradeBook book = new InMemoryGradeBook("");

            book.AddGrade(89.1);
            book.AddGrade(90.5);
            book.AddGrade(77.3);

            // Act
            var result = book.GetGradeBookStatistics();

            // Assert
            Assert.Equal(85.6, result.Average, 1);
            Assert.Equal(90.5, result.High, 1);
            Assert.Equal(77.3, result.Low, 1);
            Assert.Equal('B', result.LetterGrade);
        }