Hmm. That looks to be a bit more system-ish. My needs are for things like "widgets per fortnight", which would be tested by counting things in a database table.
I didn't make it all the way through the dox, but would "mon" accept external tester scripts?
The tests are just Perl modules that you write to implement a certain API. You could do anything in them. However, you're right that it's oriented toward system-level monitoring. I thought that was what you were looking for.