public void CheckMissing()
 {
     string doc =
     @"<?xml version=""1.0"" encoding=""utf-8"" ?>
     <Root>
         <Product>
         <Name>coke</Name>
         <Price>10</Price>
         <Ammount>5</Ammount>
       </Product>
       </Root>";
     StockManager stockMan = new StockManager(XDocument.Parse(doc));
     bool result = stockMan.CheckAvailability(new Product("nothing"));
     Assert.AreEqual(false, result);
 }
 public void CheckNull()
 {
     string doc =
     @"<?xml version=""1.0"" encoding=""utf-8"" ?>
     <Root>
         <Product>
         <Name>coke</Name>
         <Price>10</Price>
         <Ammount>5</Ammount>
       </Product>
       </Root>";
     StockManager stockMan = new StockManager(XDocument.Parse(doc));
     try
     {
         bool result = stockMan.CheckAvailability(null);
         Assert.Fail();
     }
     catch (Exception)
     {
     }
 }