With seemingly more emphasis being placed on complex pub-sub architectures, has there been any equivalent development of tooling to assist in visualizing/grokking an existing pub-sub application? In my experience at least, pub-sub architecture can be difficult to follow without good tooling (trying to keep all of these coexisting streams in your head when making changes, as asynchronous code is difficult to write a test suite for that could catch mistakes). This is somewhat just the nature of asynchronous programming, but there has been more and more emphasis on that as well with the popularity of highly responsive GUI applications and more computing capacity for background tasks.

Aside from using Visual Studio-esque "find references" to navigate to all of the locations in a codebase where a particular event stream is subscribed to, I've yet to come across much.