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