The best working environment I had the pleasure to work in had a strong emphasis on testing and software quality in general. Product teams were encouraged to spend extra time ensuring that everything worked over shipping before it was ready. The transformation it went through was incredible. Having come from a culture very much wild west through to where it was. An example of the advantages this brought was that before adopting this culture website launches were a traumatic event. Teams would block out 48 hours stretches and work solid fixing bugs at go live. Very stressful for all involved and not a healthy working environment. Contrast to where things ended up where several websites were launched on the same afternoon without a hitch. Very impressive considering the scale of the websites being dealt with (several million uniques a day).
I attribute most of these improvements being due to cultural changes that started in upper management and filtered down. In short the organisation adopted a culture of writing quality software and implemented in part by insisting on solid development process backed by a testing. This culture was so successful I remember the following happening one afternoon. Two individuals were discussing a new piece of functionality to be worked on. After several minutes discussing they convinced themselves that for a few situations that perhaps they didn’t need tests. This conversation was overheard by a less senior developer in another team who happened to sit behind them. Without pause he turned around and calmly insisted that not only would they be writing the tests they had tried to convince themselves were not required and that he would show them how to implement it.
This sort of culture where taking ownership of quality not just for your own work but for others can produce incredible results. As far as I am aware it is still being practiced as I experienced it there and I can attest to how effective it has been.