public void getFuelEconomy_Test3()
        {
            FuelPurchase.AddPurchaseFuel(TestClass.v, TestClass.v.OdometerReading + 200, 25, 1.5);
            TestClass.updateTestVehicle();
            FuelPurchase.AddPurchaseFuel(TestClass.v, TestClass.v.OdometerReading + 400, 25, 1.5);

            double result = FuelPurchase.GetFuelEconomy(TestClass.v.Id);

            Assert.AreEqual(result, 8);
        }
        public void getFuelEconomy_Test()
        {
            double result = FuelPurchase.GetFuelEconomy(TestClass.v.Id);

            Assert.AreEqual(result, double.NaN);
        }