public void AddProductDifferentPrice()
        {
            string doc =
            @"<?xml version=""1.0"" encoding=""utf-8"" ?>
            <Root>
                <Product>
                <Name>coke</Name>
                <Price>10</Price>
                <Ammount>5</Ammount>
              </Product>
              <Product>
                <Name>faxe</Name>
                <Price>12</Price>
                <Ammount>10</Ammount>
              </Product>
              <Product>
                <Name>daim</Name>
                <Price>7</Price>
                <Ammount>1</Ammount>
              </Product>
              </Root>";
            StockManager stockMan = new StockManager(XDocument.Parse(doc));

                stockMan.AddProduct(new Product("faxe", 9, 1));
        }
        public void AddProductIncorrectAmountParameter()
        {
            string doc =
            @"<?xml version=""1.0"" encoding=""utf-8"" ?>
            <Root>
                <Product>
                <Name>coke</Name>
                <Price>10</Price>
                <Ammount>5</Ammount>
              </Product>
              <Product>
                <Name>faxe</Name>
                <Price>12</Price>
                <Ammount>10</Ammount>
              </Product>
              <Product>
                <Name>daim</Name>
                <Price>7</Price>
                <Ammount>1</Ammount>
              </Product>
              </Root>";
            StockManager stockMan = new StockManager(XDocument.Parse(doc));

            try
            {
                stockMan.AddProduct(new Product("faxe", -9, 12));
                Assert.Fail();
            }
            catch (Exception)
            { }
        }