One of my goals is to add ActivityPub into my project (to make it Federated) and I’d be willing to do implementation in TypeScript and/or Java for a test suite if I had funding, because I could accomplish both objectives at the same time.
But as I said before, we really wouldn’t even need a TestSuite that much (for new apps at least) if we simply had complete JSON examples including both Request JSON and Response JSON for most of the various C2S and S2S use cases.
These examples would add so much clarity that actually most of the other documentation would be not even needed…at least to get something up and running, which is the primary challenge.