Two testing articles ...
Just passing them along.
Bugs, features, and risk — The Endeavour
All software has bugs. Someone has estimated that production code has about one bug per 100 lines. Of course there’s some variation in this number. Some software is a lot worse, and some is a little better.
Why Facebook doesn’t have or need testers | ZDNet
Summary: Facebook doesn’t have testers and doesn’t need to produce particularly high-quality software. An ex-Facebook engineer who worked at the company for four years explains why this is.
Re: Two testing articles ...
I was talking to someone from facebook at a dinner party about their lack of formal QA not too long ago. What he told me is they have a culture of peer acceptance and a lot of internal dog-fooding.
On internal dog fooding. Everyone at facebook no doubt uses facebook. So you basically have the entire company who use their product day to day, and interact with each other using facebook. So key features that everyone uses will be very scrutinized.
On peer acceptance. Think of their software release process like "Occupy Wall Street". An idea, or code in this case, is communicated with each other, and spreads to the other members, developers in this case, and those developers can choose whether or not to integrate that code into their code base. To convince another developer to adopt your code, you'll probably have a good set of unit test and automated tests to prove to your colleages, hey my code is safe. When that piece of code is adopted by most of the company, it'll get deployed.
It also help that they have a distributed system so they can do slow rollouts (target a small set of uses on release, then roll out to more users over time), and a solid and robust rollback procedure.