public void AddBillTest()
{
Car Car1 = new Car("Alfa Romeo", "Brera", "Italia Independent", 210, "Matte Grey", VehicleType.Coupe, FuelType.Diesel, Transmission.Manual);
WarehouseItem wi1 = new WarehouseItem(Car1, 10000, Guid.Parse("594e4c41-7e20-432c-9773-085d75e9b90b"));
BillOfSale b1 = new BillOfSale(wi1, Guid.Parse("594e4c41-7e20-432c-9773-085d75e9b90b"), Convert.ToDateTime("5.11.2020"));
dataRepository.AddBill(b1);
Assert.AreEqual(dataRepository.GetBill(b1.Id), b1);
}