[danparsonson]

> ...the challenge with writing tests well...

Sure, you can test more or less anything given sufficient time and force, but a massive fragile harness wrapped around the system under test is not what I mean by 'testing well'.

Also there are other things in software besides web; unit testing code that is entangled with desktop UI can be difficult or impossible without changing the original code. Try testing a WPF app that talks directly to the Dispatcher when there is no UI thread, for example.