Serious question: How would you suggest to write a test that prevents this?
You wouldn't make an assertion on clearTextPassword !== passwordHint. While developing I would think "Who will ever do that? That would be insane".
But yes, even if there is no test, this should have been caught in code review or latest when testing the OS.
But yes, even if there is no test, this should have been caught in code review or latest when testing the OS.