ReSharper: how to remove “Possible 'System.NullReferenceException'” warning

Question

Here is a piece of code:

IUser user = managerUser.GetUserById(UserId);
if ( user==null ) 
    throw new Exception(...);

Quote quote = new Quote(user.FullNam         


        

Answer 1

You do know (or expect) that this code will throw an exception if there is a null reference:

ComponentException.FailIfTrue([...]);

However, since there is no contract specifying this, ReSharper has to assume that this is just a normal method call which may return without throwing any exception in any case.

Make this method implement the ReSharper contract, or as a simple workaround (which only affects debug mode, therefore no performance penalty for release mode), just after the FailIfTrue call:

Debug.Assert(user != null);

That will get rid of the warning, and as an added bonus do a runtime check in debug mode to ensure that the condition assumed by you after calling FailIfTrue is indeed met.