For firewall leaktests there are usually web site elements, where utilising the default browser the leaktest’s web site will display what was received (often a user generated string) or not. To pass, the web site should not know about the connection attempt.
Well, both versions of CFP allow you to send any executable to Comodo for analysing. If you use Comodo’s Safe List concept, then that will get back to your version of CFP. But, that can take time, of course. I usually, as a first step, search the executable name via Google. Mostly, this answers your question. But, be advised… some search matches are automatically generated based on a file searches. So, do not be alarmed when you see words like Virus, Trojan, Spyware, etc. It’s just the page template… they know why you’re there. If you’re suspicious about a file or cannot find anything on Google, then another good site is http://virusscan.jotti.org/. You can upload any file there & run it through most of the major AV/Malware scanners in one pass. Fairly neat that.