Question

I am trying to test my controller’s create action. I am using Devise for authentication, and have used the before_filter method to limit access to the create action to logged-in users. Here is the relevant part of my controller.

class RawDataSetsController < ApplicationController
  before_filter :authenticate_user!, :except => [:show, :index, :download]

  def create
    @raw_data_set = current_user.raw_data_sets.build(params[:raw_data_set])
    if @raw_data_set.save
      redirect_to @raw_data_set
    else
      render "new"
    end
  end
end

In my test case I want to make sure that a logged-in user can create a RawDataSet. I think that I have mocked up an authenticated user according to the instructions on this blog post.

require 'spec_helper'
describe RawDataSetsController do

  include Devise::TestHelpers

  def mock_users(stubs={})
    @user ||= mock_model(User, stubs).as_null_object
  end

  def log_in_test_user
    attr = { :username => "Foobar", :email => "[e-mail]" }
    #mock up an authentication in warden as per http://www.michaelharrison.ws/weblog/?p=349
    request.env['warden'] = mock(Warden, :authenticate => mock_users(attr),
                                         :authenticate! => mock_users(attr),
                                         :authenticate? => mock_users(attr))
  end

  before do
    @rds = Factory(:raw_data_set)
  end

  describe "POST 'create'" do

    before do
      @attr = { 
        :organism_name => "Beef Jerky",
        :mass_spec_type => "My Stomach",
      }
    end

    describe "logged in user" do
      it "should create a raw_data_set when the user is logged in" do
        log_in_test_user
        lambda do
          post :create, :raw_data_set => @attr
        end.should change(RawDataSet, :count).by(1)
      end
    end
  end
end

Running this test case causes the following error:

1) RawDataSetsController POST 'create' logged in user should create a raw_data_set when the user is logged in
 Failure/Error: post :create, :raw_data_set => @attr
 undefined method `user_url' for #<RawDataSetsController:0x0000010175af88>
 # ./app/controllers/raw_data_sets_controller.rb:7:in `create'

I am baffled by this error. Upon more inspection, @raw_data_set is not an instance of the RawDataSet model class, but a user? This is what it looks like when I p @raw_data_set

#<User:0x807a06a4 @name="User_1002">

What the devil is going on? What am I doing wrong? How can I test the create action on my controller with a an authenticated user?

Answer 1

EDIT (totally wrong first attempt removed)

Calling as_null_object essentially tells the mock to accept all messages that aren’t stubbed and just return self. So when you call

current_user.raw_data_sets.build(params[:raw_data_set])

which would normally return a new RawDataSet associated to current_user, instead you get current_user again.

So when you try to call redirect, passing in @raw_data_set, you’re passing it the mock instead of a RawDataSet instance, thus the errant call to user_url.

I think the way to handle this is just use a real User (or a Factory) and stub out the Devise methods on it. So your mock_users becomes (for instance):

  def mock_users(stubs={})
    @user = User.create(stubs)
  end

Now current_user will actually do the build and save through the association.

Purists will tell you to mock and stub out everything until you’re blue in the face. Screw that — you’ve got better things to do. 🙂

The other way to approach this is to test that the build message is received without checking whether the save succeeded. Presumably your model tests will verify that saving through the association works — why test again in the controller?