Troy, 

I'm also confused about how you would have liked assertLogs to behave you say:

1. I don't want to specify the logger because I don't care which logger the message comes from.

2. I don't want it to catch messages from other loggers (whatever other means here).  But -- see 1 -- you didn't specify the logger because you don't care which logger.

What do you expect assertLogs to do when you don't specify a logger?