To have developers even primarily, much less solely, responsible for testing their own stuff is like a skydiving school that never talks about parachutes. It is utterly insane.
I've read a few people argue for that and put them on ignore without a second thought, but if companies are actually doing that, the industry has completely lost its way.
Look for "blind spots"
As for documents keeping up with code design, that's an implementation spec, which nobody had written in 25 years. Implementation details are too volatile.
Your employers are idiots who lie to you.
Those "pre-submit gauntlets" are called "quality gates," and are one of the big reasons Vista was almost three years late with only one of three goals achieved, and that one badly. We had entire hallways resigning.