I think this was discussed before wasn't this meant to be a proactive test ?
This just uses an old version of the database to see if it stops what are supposedly new malware samples. Essentially doesn't test avast pro-activity, since much of what ends up on your system comes from the internet, the network and web shields can block that content even if it is an unknown malware sample.
The network shield can block malicious sites and the web shield is very hot on hacked sites and exploits, both of which don't actually need to know what the malware at the other end might be.
Now if you just run an on-demand scans against these samples avast may not detect a specific sample, which the web or network shield could have blocked.
