My company has you write a simple twitter clone using the php framework we use. If you know the framework, it shouldn't take you more than an hour, if that. I see nothing wrong with simple projects like this. We only ask you to do it after your initial interview to make sure you're a fit personality wise.
You're screening more for knowledge of the particular php framework that you use than general programming ability. Which is fine if that's your intention.
Just like the "simple tagcloud from instagram API, shouldn't take more than a couple of hours." I got given last month.
Two hours of messing about on Instagram trying to get an authentication token for their API I eventually figured it out, only to realize I was authenticated in some sand boxed mode, so only meta-data was being returned. I needed to have the acccount approved before I could use it properly.
Your company would be far down my list. I'm not working for free if what I do isn't open source. If I'm working on a proprietary product I expect to be paid for it.
If you told me to do this take home assignment I would've politely smiled and said 'sure let me do it right away'. Then I go home, research more about your product and the market, try out your demo product, figure out how things work and release an open source version and make it free. Surely, that is a much better indicator than 'Build a CRUD using Yii'.
A few years ago, I did this to one company I interviewed at who were super arrogant and condescending. I just checked their website and it returns 404. Looks like people prefered my free open source version instead of paying them for it.
