Ok, played with this a bit, and added the Hamming Weight snippet. Seems to work fine in the solution-tryer, but I can't add a test case; even the blank default gives:

[CS1501] No overload for method 'TestCase_0710c06f5bfa4a9b9b44678df9dd933e' takes 0 arguments

Again, I'd say keep at it, and try adding a lot more content. Hell, I wonder if this is something you could even hire random CS students to add content to.