We should have unit tests, at least for the basic classes
This is far too vague to be a useful report. I'm going to hijack this report to be about a specific very complex proxy model, anything else to be tested it should get a separate bug report. Otherwise we will never be able to close this, it's too daunting to start fixing and it's impossible to close until we have tested every class we have (which is impractical).
Dear user, unfortunately Telepathy is no longer maintained. Please migrate to another solution, e.g. for Jabber a possibility is Kaidan, for Matrix a candidate is NeoChat.