Writing Tests for Rails Plugins
I really like The Rails Way by Obie Fernandez. It’s not an introduction to using Rails—look to Agile Web Development with Rails and RailsSpace for that. Instead, The Rails Way was written as a “day-to-day reference for the full-time Rails developer” (page liv) and weighs in at a hefty 851 pages, plus the preface material. It has served me well so far and it is the first resource I pick up when I need to delve into a new area of Rails development.
When I needed to develop a model plugin for Rails, The Rails Way provided an excellent overview of the process. Between that and a review of acts_as_taggable_on_steroids, I was able to get my plugin up and running very quickly. Then I wondered about writing tests for the plugin so that I can have confidence it continues to work when I upgrade to the next version of Rails. For the first time, The Rails Way failed me:
As you can imagine, testing of plugins is a lengthy topic that is primarily of interest to plugin authors. Unfortunately, I must leave further analysis of the subject out of this book for reasons of practicality and overall length. (page 649)
The book already has 851 pages, but another dozen couldn’t be spared for this topic? How does that work? In all seriousness, I wasn’t overly upset—I understand that there are limits to what can be included in a book. I would have written it off as a minor inconvenience, but I couldn’t find any good Web sites that covered the topic well. Additionally, the tests that were included with the plugins I downloaded were a bit on the lean side and didn’t provide a good example from which to work.
Fortunately, PeepCode came to my rescue. PeepCode has an excellent PDF about writing Rails plugins. It covers the common patterns for each flavor of plugin and is very thorough in its explanation about why the code is written in the manner described. It’s over 100 pages long, so I haven’t finished it yet—or even gotten to the section on writing plugin tests—but it has already proven to be the best resource I’ve found concerning Rails 2 plugins. I recommend it without hesitation for anyone seeking to write their own plugin or understand someone else’s plugin.
