RSpec Tips & Tricks

Throughout the last couple of days, I did a bigger refactoring of our Ruby on Rails application. As I changed quite a few moving parts, I covered everything I did with RSpec. It’s really an incredible feeling to have all your bases covered with automated tests when you finally start the manual regression test. Along the way, I came across a few things I wanted to share with you.

Structuring Your RSpec

When you’re writing specs you want to bring order to them sooner or later. I really use nested describe-blocks a lot. Let’s look into a Controller spec to see what I do:

Every controller spec starts with a describe block like this:

describe QuestionController do

end

For spec’ing out individual actions in the controller, I usually create one describe block for every public method in that controller:

describe QuestionController do
	describe "index" do
  end
end

Inside that describe block I put all the it-specs themselves. Usually, I start by writing only the expectation and later I fill it out:

describe QuestionController do
	describe "index" do
		it "should redirect to 404, if no questions are found"
		it "should prepare a list of ten questions"
		it "should redirect a not logged in user to the login page"
  end
end

Running specs from the command line

I use RubyMine for my ruby development but despite it’s capability of running specs within the IDE I prefer to run them separately on the command line. For running only the part you’re currently working on the -l parameter comes in handy. You can pass it any line number of an it or describe block and it runs only what’s there. This is especially cool for describe blocks as it runs all specs inside that block – and only those.

If you structure your specs like me using nested describe blocks, this is really nice.