Is FediTest just for testing ActivityPub?

Nope, FediTest is a general framework for testing distributed systems, in particularly those that:

• have heterogeneous Nodes, i.e. Nodes that run software built by different people, potentially with different feature sets, and using different tech stacks. Like the many applications of the Fediverse that nevertheless need to communicate.

• use complex protocols, like the stack that makes today’s Fediverse work, which already includes ActivityPub, ActivityStreams, WebFinger, HTTP Signatures and more.

• with non-trivial distributed state, i.e. where just getting the (decentralized) system into the state necessary before a test can be run is not so simple.

This is also a reason why we keep the actual tests in a different Git repository.