Beautiful Testing

Testing XMPP Protocols

One of the important aspects of an XMPP application, be it client or server, is the actual implementation of the XMPP protocols. Every XMPP implementation needs to at least implement the XMPP core protocols, as standardized by the IETF in [RFC 3920] and [RFC 3921]. These protocols provide the basic building blocks for XMPP, describing how an XMPP connection is set up, and what you can send over it. On top of the core protocols, the XMPP Standards Foundation created an ever-growing list of XMPP Extension Protocols (XEPs). These specifications describe how to extend the core protocol for very specific features, ranging from simple things such as requesting the software version of another client (standardized in [XEP-0092]), up to complex protocols for negotiating audio/video conference calls between clients, transferring files, and so on.

This text focuses on testing the functionality of XMPP protocol implementations, answering questions such as, “Does my client correctly respond to incoming requests?”, “Does my client send the right requests at the right time?”, “Can my client handle this specific response on this request?”, and so on. We start out by looking at the most simple request-response protocols, after which we gradually move up the ladder to more complex protocols. While the complexity of the protocols increases, the level at which the tests are written becomes higher as well, moving from very specific unit tests up to full system tests. ...