Like with Apache, with Varnish 3 you can test the syntactic correctness of your VCL files without having to roll some dice restarting a running server.
$ varnishd -C -f /path/to/mysetup.vcl
> ...
Varnish will compile the file and print out it's full configuration as output. If there's an error, varnish handily gives you a compiler error to help trace what went wrong, which could look something like this
> Message from VCC-compiler:
> Expected an action, 'if', '{' or '}'
> ('input' Line 82 Pos 6)
> vcl_hash(req.http.Cookie);
> -----########------------------
>
> Running VCC-compiler failed, exit 1