This is from a while back, but I finally got around to watching it. I think it is a really good questioning of our assumptions around testing (and of course it is a controversial talk - it is DHH)

To me, the TL;DR was: 

- The main goal of writing code should be creating maintainable code with clear intent. 
- While unit testing is good, it is not a panacea for planning good architecture or system testing. 
- Good unit testing coverage will not spontaneously birth good architecture and at times it can even work against code clarity.  
- System testing is a better representation of how our code works 
- Unit testing should support our goals, and not become a goal in and of it self.

I highly encourage everyone to carve out some time to watch.

Corey Floyd
Software Engineer 
Mobile Apps / iOS 
Wikimedia Foundation