Test your app with RSpec

Created by Clemens Helm, @clemenshelm and Floor Drees, @floordrees

RSpec is a Ruby testing framework, that describes our application’s behavior in a syntax that doesn’t look much like Ruby. It outputs test results in your terminal, so you’ll test your reading skills as well (pun intended).

COACH: Talk about testing and Behavior-Driven Development.

Install rspec

For starters, let’s install RSpec and all of its dependencies.

gem install rspec

Then we call

rspec --init

in our project directory. This creates spec_helper.rb in the spec folder, and .rspec.

Rubyists often use the words ‘test’ and ‘specification’ interchangeably, that’s why you’ll store your tests in the ‘specs’ folder. Save your test as idea_spec.rb (<name_of_spec>_spec.rb).

Inside that new file, write:

require "spec_helper"
require "idea"

Next, let’s describe one of our specifications

describe Idea do
  it "has a title" # your examples (tests) go here
end

In your terminal run

rspec spec/lib/idea_spec.rb

which will output that your test is pending as it’s not yet implemented.

COACH: Talk about googling terminal output.

Let’s do something about that!

describe Idea do
  it "has a title" do # yep, you can totally use 'it'
    idea = Idea.new # creating a new idea 'instance'
    idea.title.should be_true # this is our expectation
  end
end

should give you a more satisfying output.

Refactoring

You could actually also write:

describe Idea do
  its(:title) { should be_true }
end

which looks a lot nicer, but there’s a lot of magic involved. For now it’s probably jyst nice to know that we can ‘refactor’ those big chuncks of code into smaller bits with a little more experience.

COACH: Talk a bit about refactoring.

Marking to-do’s with tests

Yeah! To-do lists. Awesome. A nifty RSpec feature is the functionality to mark certain tests as pending.

Leaving out the do and the end in the example body, like so

it "has a title"

will mark a test as pending. For bigger applications, where you want to tackle one test at a time, you can also add an x in front of an example, making it read

describe Idea do  
  xit "has a title" do
end

or use the word pending in your example.

Behavior-Driven Development

Normally we would go about BDD testing in a slightly different way. Thinking about the application we want to build, we’ll write down our expectations and then start building step by step, with the specifications in mind.

We’d first write

describe Idea do
  it "has a title"
    idea = Idea.new 
    idea.title.should be_true 
    # or, alternatively: idea.title.should == true
  end
end

and only then create a file named idea.rb introducing the idea class

class Idea
attr_accessor  :title
end

as running rspec spec/lib/idea_spec.rb in your terminal before you’ve implemented that class will throw you an error. Luckely, errors are nothing to be afraid of. RSpec errors actually help you write (the necessary) code!

Try and write tests for the follow up guides to check if you’re implementing ALL the right things.

describe Attendee do
  it "tests everything"
end

Just saying.

Happy testing!