Agree that the code is clear. It's just that if this test fails in a Jenkins run, you only see the line, and no message. So you have to _go_ to the code to see what went wrong. Adding a message makes it clearer what the actual failure is.

In cases like this where there's only _one_ assert, the name of the test indeed is enough, so I'm also fine with leaving as-is. Once you have multiple asserts in a test, though, it's useful to be able to see which one failed.