I'm doing that right now. One bit that was a bit confusing and I don't know if this is relevant place to be asking is on "Moving to The Next Pair" section. Like how do I know if it's okay to move to the next pair? Because in core.js it seems to pick a winner of the pair as soon as it's called. (It probably talks about this further down but this kind of threw me off)
Other than that you're right. It's one of the complete tutorial that makes TDD actually enjoyable. However, that has mostly to do with how redux and immutability has been used in the tutorial.
I was a bit confused by this as well. Later in the tutorial, you will build a separate "Results" view that shows the tally of the current vote and lets you manually move to the next vote by triggering the 'Next" Redux action. Hope that helps.
Also for those interested in more on Redux, there is an excellent Getting Started tutorial by Dan Abramov (its creator) on egghead.io:
http://teropa.info/blog/2015/09/10/full-stack-redux-tutorial...
Learning Redux from the get go means you can skip a lot of React's internal state management / lifecycle methods.
The tutorial also covers a bunch of relevant topics like TDD with React, immutable.js, and socket.io.