public void MonthlyStatistics() { var sut = new DrivingJournal(); sut.AddEntry(2017, 9, 10, "Drive this month to daliver goods"); sut.AddEntry(2017, 9, 10, "Drive this month to daliver goods"); decimal milesDriven = sut.MilesDriven(2017, 9); Assert.AreEqual(20M, milesDriven); }