What kinds of tests do you write for your MVC app?

[sgringwe]

I am starting to do some testing on my Rails app and hopefully switch to full TDD soon. Before I get too far in I am trying to determine what types of tests I want to write. Rails gives you lots of choices:

[sgringwe]

Hmm, the text was cut off. To continue the question:

models, controllers, requests, routing and views tests.

I also use knockout.js in my application and was hoping to use karma test-runner or a similar javascript testing framework.

Which tests should I use and which are not worth the time? What is the right combination?