There is lot of code.
Onista is amalgam of eBay, Priceline, LendingTree, Alibaba and LinkedIn. When I say that, what I'm trying to say is that site has lots and lots of features. We have done testing using different data set and lots of scenarios to find bugs.
We also redesigned lot of features.
It did take us to fix close to 2k bugs to get to stable state.