Last week there was an interesting discussion about coding samples on /.  As if technical phone interviews weren't enough, some companies would like or even require you to submit a coding sample for their review.  These come in various flavors, but I've encountered 3 variations of this:

1. Random code sample of your choosing.
2. Code you write on site while interviewing, usually on a whiteboard.
3. Take home test where you complete a specific assignment.

Of the 3, the first one is pretty liberal and for the most part I would expect any decent programmer to be able to come up with some pithy example.  Sure, not all of us spend a significant part of our time writing code outside of work, but you should have something. 

I think OSS contributions are the best way to answer this type of request - even if you're the only one who uses it.  Its a very simple matter to setup a public OSS Google code playground.  Better yet, submit a patch for your favorite OSS project.  This shows not only you know how to code, but that you can work with existing code on a large project with other people - something you will not likely learn in college classes.

To me, these type of requests are nothing more than a starting point of a discussion between you and a prospective employer.  Which also means, any code you find that is public domain could be turned in.  Is this valid in this context?  I think so, because the code should be a discussion topic and not a test.  You should be able to talk about patterns used, coding standards, and most importantly... what would you do to improve this piece of code.  Clearly you must understand the code to be able to do this.

Writing code on a whiteboard (#2) is a bit different than one or three.  Its real time coding.  Coding under pressure without the aid of intellisense, IDE, or other technical reference.  Everything is based on your recall which only happens through experience, or at least good memorization.  More on this topic later...

Number three is interesting.  Often time the assignment is very particular and requires your to solve a particular problem, often times academic in nature.  This basically means homework; something you won't do in real life, nor something you have laying around already coded.

I think these type of coding samples are particularly useless for several reasons.

1. Good coders often won't waste their time tackling these problems unless they are really interested in the position.
2. They aren't real world and won't likely come up in real life.
3. These type of tests take time.  Why would a highly sought after engineer waste several hours with a home work assignment?

There are probably more reason than the three I stated, but that's more than enough reason for most good candidates to forgo application.

My question is why do companies do this?  Last I checked neither Microsoft or even Google do anything like this.  Perhaps to filter out the truly dedicated?  Maybe...  but perhaps its because someone non-technical is reviewing these tests?

Companies that do have a programming test of sorts like this are just lazy.  They are unwilling to take the burden of weeding out the good from the chaff, so they put the burden on the candidate with these tests, I mean hoops.  To me, these type of tests are a red flag. Perhaps this works for a small minority, but I surely wouldn't want to work somewhere like this.

A good software company should use code as a starting point for a discussion about software and systems.  Particular design decisions made in a complete vacuum are irrelevant without context.  Its all about the context, and that should just be the starting point of a bidirectional discussion, because that's where the real discovery comes from.