Lets say we have an Articles controller with an index we want to spec:

 
class Articles < Application 

We could spec this index action to make sure it always fetches the articles from the database in descending order by date:

 
describe Articles do 
 

This will make sure the index action will always display the articles in descending order without actually querying the database or rendering the view, meaning you don’t have to worry about populating the database from fixtures or rendering errors.

Lets add a show action with an id parameter:

 
class Articles < Application 
 

And the spec for an action with a parameter:

 
describe Articles do 
 

Notice that the request path and method are not specified anywhere. Merb allows you to invoke an action without specifying the request method, keeping your routes removed from your controller tests. If you want to spec your routes (and you always do), Merb provides helpers & matchers specifically for testing your routes. See the Routing Specs for more.

Taming Spec Complexity

Sometimes your specs can grow quite complex. It’s often handy to abstract away some complexity. Here are some tips for handling complexity with abstraction.

Handling Requests

Did you notice in the above examples the frequent usage of dispatch_to? It’s sometimes best to wrap up the test request to your controller so that each example in your spec is making the same sort of request. For example:

 
  describe "requesting /pages with GET" do 
    before(:each) do 
      Page.stub!(:all).and_return(pages) 
    end 
 
    def do_get 
      dispatch_to(Pages, :index) do |controller| 
        controller.stub!(:display) 
      end 
    end 
 
    it "should be successful" do 
      do_get.should be_successful 
    end 
 
    it "should load all page records" do 
      Page.should_receive(:all).and_return(pages) 
      do_get.assigns(:pages).should == pages # pages is defined elsewhere 
    end 
 
    it "should display all pages" do 
      dispatch_to(Pages, :index) do |controller| 
        controller.should_receive(:display).with(pages) # pages is defined elsewhere 
      end 
    end 
  end 

The method do_get neatly summarizes the most common request we’re making in our spec, handles any stubs, and has a wonderfully descriptive name to describe what’s happening.

Notice in the last example in the above spec that we don’t have to use do_get. In this last example we hand write our usage of dispatch_to to ensure that a particular method is being called.

describe Articles do 

class Articles < Application 

describe Articles do 

class Articles < Application 

If your action’s behavior depends on the request method, the get, post, put, delete will allow you to fake the request method.

 
 
class Articles < Application 
 
  def index 
    @articles = Article.all(:order => 'created_at desc') 
    display @articles 
  end 
 
  def show(id) 
    @article = Article.with_slug(id) 
    raise NotFound unless @article 
    display @article 
  end 
end 
 

 
 
  describe Articles do 
 
    describe "#show" do 
 
      before(:each) do 
        @article = mock(:article) 
      end 
 
      it "should display the article matching the slug id" do 
        Article.stub(:with_slug).with("slug").and_return @article 
 
        dispatch_to(Articles, :show, :id => "slug") do |controller| 
          controller.should_receive(:display).with(@article) 
        end 
      end 
    end 
  end 
 

It is also a good idea to stub the render and display methods for your controller. These methods invoke the view, which should be left to the view specs.

Examples

Lets say we have an Articles controller with an index we want to spec:

 
 
  class Articles < Application 
    def index 
      @articles = Article.all(:order => 'created_at desc') 
      display @articles 
    end 
  end 
 

We could spec this index action to make sure it always fetches the articles from the database in descending order by date:

 
 
  describe Articles do 
 
    describe "#index" do 
 
      it "should get all articles in descending order of date created" do 
        Article.should_receive(:all).with(:order => 'created_at desc') 
 
        dispatch_to(Article, :index) 
      end 
    end 
  end 
 

Keep In Mind

Controller specs work best when the interaction with models have been completely stubbed out. Checkout the RSpec documentation for more info on how to stub & mock for your models.

Examples