And a company of engineers, a distributed database, a web crawler, PageRank, a monetization system to fund it, and a bunch of datacenters is all that prevented us armchair TDD quarterbacks from having a hit search engine. :P

They obviously do a bunch of testing already. Maybe if they’d spent any more effort doing testing early on, some butterfly-hurricane chain would have caused them never to gotten so big so fast.

It’s easy to criticize. But we wouldn’t have anything to criticize if they hadn’t first built the one website that basically directs the entire web today. Why aren’t we praising the little-fish search engines for winning the battle but losing the war?

A test that would make more sense is to run a list of trusted sites (e.g. google.com itself) through the filter. If any sites fail then there is likely a major problem in the classification code. It’s not foolproof, but would go a long way to detect the sort of catastrophic failure we saw.

To define a good testing cases for all the possibility is not easy. People and company are learning from mistake. Let hope that they will do better. However, what I don’t like is Google’s monopoly power. Somebody need to do something so we will NOT depend on google alone.

How many other teams validate production configuration before they deploy it?

Good point. But if the post from Marissa Mayer indicates that google manages very important things such as this with a file checked in… then I think the team should feel compelled to be paranoid.

For me, testing replaces Fear with Boredom.

@Sebastien,

Great to hear some passion in the comments! In my experience a well tested codebase is much more flexible. Code that just works magically and only is observed in a full integration test, or by starting it up and using it is very brittle. Big code always needs refactoring, sooner or later. Tests give us the power to actually refactor.

It is interesting that a text file is used to list these sites. You would be expecting something like a database with associated controls and tests around what can possibly be valid data, right? Well, if you built a whole app to do it — I think tests would be sensible. Just because it is a simple text file does not mean it should not be tested.

There is a complexity branch on every one of the urls in that list. We could think of this data as highly complex, and warranting extensive testing. Especially if there isn’t another application on top of it all (which would probably have tests around the models).

TDD says to stop testing when you can’t think of anything more to test. Humans aren’t perfect; we make mistakes and sometimes we don’t think of every possibility.