This is the source code for my blog. It is pretty minimalistic and does not do anything that is very fancy. It is also small enough that I have not felt the need to test-drive it as I am mainly coupling together components which are known to work quite well (Ruby, Sinatra, Markdown, etc).
That said, I have written tests for some things.
Posts are written in Markdown which then get sucked into the actual web view. Theoretically this whole thing could be hosted on GitHub, but it is more fun to write your own blogging software. :)
Lastly, while my blog probably gets close to nil traffic, I am trying to see far I can push the old Heroku Bamboo stack in terms of caching. My hypothesis is that if you know HTTP caching sufficiently well, one web process should scale quite nicely for static content.