Whenever I tried to learn TDD, it only seemed relevant for back-end testing (eg REST APIs). But is there anyone left who is strictly a back-end guy? Most programmers now bill themselves as full-stack app developers, and probably spend at least half their time working on the front-end/UI.

I hadn't heard of functional testing before. From a stackoverflow answer:

> Functional Tests are written from the user's perspective. They ensure that the system is functioning as users are expecting it to.

This makes much more sense to me than TDD. TDD is writing functions which test other functions. Are the users writing code, and passing arguments to function calls? If not, then time spent on TDD isn't adding much value for the users.

So what does it mean to write functional tests? I'd argue that writing modular React components is a form of functional testing. Devcards[1] is similar, and looks to me exactly like what would be considered functional testing. These two workflows feel much more natural than testing UIs methods like automated selenium browser interactions to generate screenshots.

1. http://rigsomelight.com/2014/06/03/devcards-taking-interacti...