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Spec Your Views

Posted by Thu, 02 Aug 2007 07:00:00 GMT

I meant to work on this post… oh about 7 months ago.

Way back in January (7 months ago), Jamis Buck posted an article titled, Testing your views, which gave a few tips on using Test::Unit to, as the title suggests, test your views.

While, I’m not going to rewrite everything that Jamis wrote, I’d like to show you how to test these views with RSpec. (you might take a moment to quickly read his post…)

In this example, I’m going to show you how we’re able to write specs for the following RHTML, which you’ll notice matches the code that he wrote tests for.


  <% if @user.administrator? %>
    Hi <%= @user.name %>! You appear to be an administrator.
    <%= link_to "Click here", admin_url, :id => "admin_link" %>
    to see the admin stuff!
  <% end %> 

Jamis writes, “The only really significant thing you ought to be testing here is that the admin link only shows up for administrators. “

So, let’s do just that, but with RSpec.

I’m not sure how Jamis is handling his view tests, but we’re going to approach our view specs, much like we approach our controller specs, with the use of mocks and stubs, because we really don’t need to spec any of our models at this level in the application.

Tip: Write specifications for your models… in your model specs not in your controller or view specs.

The first thing that we’re going to do is setup a custom spec helper, because for something like an mocked user, will probably get reused in other areas of the user interface. Spec helpers are essentially modules that you can include in your RSpec descriptions (the block that starts with describe) and reuse.

In this spec helper, I’m going to include two methods, to mock the User model and stub out any of the methods that are necessary for spec’n this view.


module MockUserHelper
  def mock_normal_user
    user = mock(User)
    user.stub!(:administrator?).and_return(false)   # <--- NOT an admin
    user.stub!(:name).and_return('David Chelimsky')
    return user
  end

  def mock_admin_user
    user = mock(User)
    user.stub!(:administrator?).and_return(true)    # <--- IS an admin
    user.stub!(:name).and_return('Aslak Hellesoy')
    return user
  end
end

In the mock_normal_user method, we’re constructing a mock object and stubbing out the methods that we see are being called in the RHTML code. In mock_admin_user, we’re basically doing the same thing, but just stubbing the administrator? method to return true for this mock user.

By stubbing these methods, we’ll be able to send a non-ActiveRecord object to the view and have it render without knowing the difference. For example, the if @user.administrator? condition will return true or false, depending on how we stubbed it.

For more information on mocks and stubs, read here.

Now that we have our spec helper, let’s go ahead and dive into a few specifications for the view.


describe "index page" do
  include MockUserHelper

  it "should render an admin link for an admin user" do
    assigns[:user] = mock_admin_user
    render 'index'
    response.should have_tag('a#admin_link')
  end

  it "should not render an admin link for a normal, non-admin user" do
    assigns[:user] = mock_normal_user
    render 'index'
    response.should_not have_tag('a#admin_link')
  end
end  

Please note: This code example is only longer than the one shown by Jamis because he didn’t include how he setup all his user sessions/objects. ;-)

When these specs are run, we can see the following results.


Pretty output courtesy of RSpec + TextMate bundle

Great, we’ve been able to write specifications for our Rails views without a lot of pain. Stay tuned for more posts on this topic as I continue writing about how Designers and Developers can work together, in harmony. (see my last post on this topic)

For more information on adopting RSpec, please visit the RSpec project homepage.

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