Does puppet syntax check classes that are not part of the node

edit

Are you asking about 'unexecuted' code in your module directory?

If you have a bogus, faulty module, puppet will try to parse it (for custom facts, functions, etc..) but if it's not a part of the actual resource chain that your node is using, it shouldn't interfere. If it is only puppet code it shouldn't be a problem. Facter facts and functions can sometimes cause issues though.

Have a look in the code:

      files = FileList["**/*.pp"]
      files.reject! { |f| File.directory?(f) }
      files = files.exclude(*PuppetSyntax.exclude_paths)

So all *.pp files (note it checks at the level of the pp file and is not class aware) are checked, unless explicity excluded, regardless of whether or not they're actually used.