>  do I add the tests for realtime epochs or does @mluessi already have something in mind/made some progress here. Do we need tests for the real client too? How would we do that?

I think the reason why we have the mock is probably because the realtime tests wouldn't be so easy to get...
What I had in mind is to put everything beyond a simple data sending / getting tests for the mock client in the related RtEpochs test, namely iter evoked et al.

> We should probably have an if condition in our mockclient that checks this and somehow exits gracefully instead of getting stuck in a loop. What do you think?

Yes, we somehow need to make the third conditional in RtEpochs.next come True or try to add some exception in the mock client.