Ryan Bigg

When to Cuke

03 Mar 2011

I think Cucumber is great, but not great for everything. Many people (including myself) use it and swear by it. You get to write features in English (or other languages), man. It's really awesome if you want to show these stories to people who you're developing for as they can read it and understand it.

I personally feel, in some cases, Cucumber isn't the right solution. If you're developing something that has no non-Ruby savvy stakeholder, why would you write it in Cucumber? I personally don't see the point. It overly complicates things.

Take this example: I want to create a feature for posting a new comment on a post. It would go like this:

Feature: Comments
In order to tell the masses what's on my mind
As a user
I want to post comments on the site

  Given there is a post:
    | title        | text                         |
    | When to Cuke | I think Cucumber is great... |

Scenario: Creating a comment
  Given I am on the homepage
  When I follow "When to Cuke"
  And I fill in "Text" with "I am posting a comment. Look at me go!"
  And I press "Post Comment"
  Then I should see "I am posting a comment." within "#comments"

I've tried to keep it as simple as I can here, but it should demonstrate the point I am trying to make. The logic of how the "Given there is a post" step is defined something like this:

Given /^there is a post:$/ do |table|
  hash = table.hashes.first
  @post = Post.create!(hash)

Where's it defined? Well, it could be anywhere. That's the problem! Usually, I'd define this in a file at features/step_definitions/post_steps.rb because it deals with Post objects, but that's just me. People have different tastes and therefore, undoubtedly, will do it differently. Maybe I've been too mollycoddled by Rails, but this is completely arbitrarily decided by whoever's writing the feature at the time. It gets to me.

Oh, then what happens if you want to have some kind of association, say you want to add an author to that post, transforming the step into this:

Given there is a post:
  | title        | text                         | author                  |
  | When to Cuke | I think Cucumber is great... | radarlistener@gmail.com |

Yes, it's an email address. But what does it mean? Well, that behaviour would have to be defined in the step definition, which is "in another castle".

Given /^there is a post:$/ do |table|
   hash = table.hashes.first
   hash["author"] = Factory(:user, :email => hash["author"])
   @post = Post.create!(hash)

There's no way you can specify a pre-existing Ruby object to be a value for one of the keys in the table in Cucumber. Therefore, you have to hack around it like this.

Additional gripe: I'm constantly typing "Given I" and "When I" and "And I". Boring. I'm a programmer, coding a site that programmers will use. Why am I writing it in English?

Enter: Capybara

Now let's see this same test, but written as a Capybara integration test:

describe "Comments" do
  before do
    Factory(:post, :title => "When to Cuke",
                   :text => "I think Cucumber is great...",
                   :user => Factory(:user, :email => "radarlistener@gmail.com"))

  it "creating a comment" do
    visit root_path
    click_link "When to Cuke"
    fill_in "Text", :with => "I am posting a comment. Look at me go!"
    click_button "Post Comment"
    within("#comments") do
      page.should have_content("I am posting a comment. Look at me go!")

No bullshit, everything's there that I need to understand the spec. There are no step definitions. I can "parse" this code much faster in my head than I can with its Cucumber brother, allowing me to be a more productive developer. There's nothing extra on the lines. No "Given", no "When", it just does things. There's nobody on my team that doesn't understand this code.

Note also here how I'm able to pass through an object to the user key in the Post factory without having to hack around it.

Simple, elegant and effective. Yes please. Oh, and it's shorter too. I'm using RSpec + Capybara to develop the forem gem (eventual aim: a decent forum engine for Rails 3) and I'm loving it. It just works, and there's no extraneous syntax in my specs.

If you're working with people who aren't technically-inclined then perhaps it would be easier to use Cucumber, as it is the easiest to read. But when working on a team of Ruby developers, developing something internal, I think Capybara is the way to go. If you're looking for a way to combine the two techniques then I'd recommend taking a look at cavalle's steak gem, or this post by Jeff Kreeftmeijer, showing how to do it with straight Capybara.

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