Link is surprisingly good.
SOMEWHAT UNRELATED ANECDOTE: Game developers seem to be about 5-7 years behind the status quo for software development practices at all times. As I was playing through Skyrim the first time, a bunch of quests broke-- enough that it was bugging me so I restarted a new character. The second time I used an entirely different strategy for competing quests, and I still ended up with a crapton of broken quests.
At the time, I was thinking: "man, whatever unit testing framework they're using to test quests did a pretty crappy job!" There's hundreds of quests, not even counting the randomly-generated ones, and they interact like crazy. I mean, each part of a quest involves setting flags, moving items/NPCs around, moving inventory items around-- surely they have some automated way of running quests to ensure that quest Foo would never destroy an NPC still required by quest Bar, or that taking the item required for quest Fizz in the same dungeon where the target item for quest Buzz is wouldn't break Buzz even before you even got the quest in your quest log... I mean, this stuff is trivially easy to test, they could have a couple machines in a basement somewhere just running through the quests in random order, right?
It didn't occur to me until later that they weren't doing unit testing of quests at all!
When Bethesda released the "Creation Kit" (i.e. the game editor for Skyrim), I looked into it. Unit testing for quests? Not there. No hooks to add it. Pathetic. No wonder the end product was so buggy...
<- I couldn't make my shit work, so here's a Godzilla head.