I've been planning to get into Go so the book looks interesting. One question though: How far into the book do you introduce tools for automated testing?
What I am thinking about doing is writing a companion book that covers git, testing, etc. Eg after every chapter the companion book then walks you through writing tests, committing to git, merging it into master, etc. That way someone could optionally choose to do those things along the way. I might also experiment with other formats, but time will tell.