If that sounds very intimidating, don't worry! The Rails router actually comes with a debugging tool that could generates an interactive visualization of your router NFA.
To generate one for your app, simply run Rails.application.routes.router.visualizer from your Rails console and save the returned string into an html file. (You will need the dot command-line tool for this – OS X users can get it from homebrew with brew install graphviz.)
Oh, is it not working? I forgot to mention that this tool is broken on Rails 5 by an internal refactor. Don't worry though, because Seth fixed it for us in this pull request, which would come out with the next 5.0 patch release. If you are impatient, you could try it out by running the 5-0-stable branch.
Before you build your next billion-dollar startup with this awesome tool, please note that this is an undocumented (private!) API, and as you can see, could break unexpectedly between versions (or go away entirely).
While it's definitely not Production Grade™ software, it's still very useful for learning and debugging purposes. Enjoy it while it lasts!
When dumping the schema, Rails tries to align things vertically for readability. However, this could result in a bigger diff than you would like when making changes to an existing table. With this PR, you now have an option to turn that off!
While integration tests are strongly preferred over controller tests going forward, this PR allows you to simulate a request content type in controller tests using the same as: :json (or as: :xml, and so on) option.
This is a periodic PSA that when it comes to upgrading Rails apps, the update task is going to be your friend. In Rails 5, this command has been renamed to rails app:update, whereas when upgrading to Rails 4.2 and below, you would want to use rake rails:update instead.
In case you missed it, Active Job in Rails 5 defaults to using the "async" adapter for jobs processing (the previous default was the "inline" adapter). The documentation has been updated to reflect that change.
That's it from This Week in Rails! As always, there were a lot more changes than we have room for. If you are interested, definitely go check them out yourself!