@Maks3w Thats a great question, the fact is, the function converts the code to include the @ symbol, I think it would be weird to throw an exception if one includes the @ symbol, seeing as the result of the function outputs the correctly formatted query.

The reason I included that test was to ensure that when an @ was included that the double quotes were converted to a single quote, so the 2 were consistent.  It does seem odd to me that the CSS2XPath is modifying this query in general, and perhaps that is the modification that needs to be made in this regard, IE> ignore attributes?  Unfortunately I don't know enough of the history of this class to make that decision.