[Zope-dev] ExtensionClass is not of type Class?!

Hi, I guess I'm doing something wrong here trying to write tests for Squishdot: Traceback (most recent call last): File "testSquishfile.py", line 16, in testAddFile assert isinstance(theFile,Squishfile) TypeError: isinstance() arg 2 must be a class or type Given the above, I put a "print Squishfile" in the line above the assert, it gave: <extension class Products.Squishdot.Squishfile.Squishfile at 010ABC48> So are extension classes not usuable with isinstance? If not, what should I be doing to check I'm creating an object of the right type? If they are usuable, then what am I doing wrong? cheers, Chris