nUnit Testing for Smart Documents Question

Recently, a reader of my blogsent me an interesting question that I could not answer. I thought I'd share it with you and see if you have an answer:

I am writing a Smart Document solution in Word, and am trying to setup unit tests with nunit. I have posted to several managed and unmanaged newsgroups with no answer. I have found myself visiting your blogs for answers more than any other site, and thought you might have an answer. I can't seem to get a reference to ISmartDocument that works.. I have tried:

Microsoft.Office.Core.SmartDocument sdDoc = wdDoc.SmartDocument;
ISmartDocument m_iSmartDoc = (ISmartDocument)sdDoc;

It builds fine, but nunit fails indicating a syntax error. Have you or anyone you know of successfully performed unit testing on a Smart Doc? I would love to see an example.

Derek Sanderson

Any Ideas?