STP uses the following lists: (social-tracking-protection-facebook-digest256, social-tracking-protection-linkedin-digest256, social-tracking-protection-twitter-digest256). We have to check each of these individually, but if the feature is working correctly all three should be blocked (or not blocked) depending on which configuration you're testing.
Test will say "Blocked" if Firefox is blocking resources from that list.
social-tracking-protection-facebook-digest256:
social-tracking-protection-linkedin-digest256:
social-tracking-protection-twitter-digest256: