public void Update1IsOK()
        {
            var context = new CarContext();
            var testContext = new EFRepository<Car,int>(context);
            var all = context.Car.ToList();
            all.ForEach(r => testContext.Delete(r));
            testContext.Save();
            var car = new Car()
            {
                CarName = "Ford",
                CarPrice = 100000
            };
            testContext.Insert(car);
            testContext.Save();
            car.CarPrice = 99999;
            car.CarName = "Ford1";
            testContext.Update(car, x => new { x.CarPrice });
            testContext.Save();
            var cars = testContext.GetDbSet().AsNoTracking().ToList();//OK


            var cars1 = testContext.GetDbSet().ToList();//error            
            Assert.AreEqual(cars.Count, 1);
            Assert.AreEqual(cars.FirstOrDefault().CarName, "Ford");
            Assert.AreEqual(cars.FirstOrDefault().CarPrice, 100000 - 1);
        }