I have a problem and it goes like this: I need to implement a client for a client-server interaction over a specific protocol. Now I only have a loose document ( yeah I Know..) which documents the protocol. How would you approach to implement the server? I mean can you share any experiences similar or ideas on how to test the Interaction as "best" as possible? How would you test client - server interactions in general? using queues and state machines? When I'm trying to google for potential solutions or advice I'm "seeing" by the quality of the results that I don't use the right search terms. Any resources or advice appreciated!

if you can sniff the traffic between the client and server of another implementation it would be easy to reverse engineer

Thank you for suggesting wire shark

Another 'wire' might be useful: wiremock.

Not sure that it is what you are really looking for, but if you want to test the logic of the protocol independently of the implementation, you can use TLA+ which "is used to design, model, document, and verify programs, especially concurrent systems and distributed systems."