I get the hesitation that things can turn into lies, but that's a sign that you're doing things wrong. That also tends to happen to comments that are far away from the relevant code, like the documentation of a 100 line function. The function can change while the comment is no longer visible on the screen, so it's easy to forget to also fix the comment.

But test strings like that are designed to avoid that problem. They're right there next to your tests for a reason. You should always be right next to them when you're changing the test.

Fundamentally, this is something that has to be addressed with code reviews. If someone can commit their changes to a group repository without anybody else seeing them, you're going to get stuff like this. As soon as you get decent code reviews, you can just reject a change where there are tests without documentation, the same way you can reject a change to a test where the documentation is now out of date.