cabal-dev install snap-0.8 reports that snap, snap-core depends on hunit-220.127.116.11 which cannot be found. It is not listed on the hackage page as a dependency.
cabal-dev install hunit-18.104.22.168 claims there is no available package and cannot install it so that seems to be the cause of the error. Sorry to waste time.
Yeah, everything works for us. I'm not sure what's going on for you. hunit-22.214.171.124 is on hackage, so it should be available. Can't say much more without detailed information.