Rspec 2 and Rails 3 stubbing / mocking

Question

I am currently in the process of migration to rails 3 from rails 2 in a large application. In our functional specs, we have alot of stuff like this:

@model = Factory :model
@child = Factory :child
Model.stub!(:find).and_return(@model)
Child.stub!(:find).and_return(@child)

...

@child.should_receive(:method).twice

The main issue is that if I let it hit DB and get actual instance of child, real :method makes tests too complex (need two big factories) and slow.

In code we use various ways to get items: find, dynamic finders, etc

@model = Model.find(1)    
@child = @model.children.find_by_name(name)

How would you advice to move this logic to rails 3? Any advice on another stubbing/mocking library maybe?

Answer 1

Normally you would mock the model inside controller specs:

Model.stub!(:find).and_return(mock_model('Model'))
Child.stub!(:find).and_return(mock_model('Child'))

However, when you've got gem "rspec-rails", "~> 2.0" in your rails 3 app's Gemfile, then the standard rails scaffold generator will use rspec to generate specs for you, so running rails generate scaffold MyResource will generate some example specs for you.

The following is a lightly annotated version of what rails/rspec will generate for controller specs, so I suppose this should be considered "The RSpec Way".

describe AccountsController do

  # Helper method that returns a mocked version of the account model.
  def mock_account(stubs={})
    (@mock_account ||= mock_model(Account).as_null_object).tap do |account|
      account.stub(stubs) unless stubs.empty?
    end
  end

  describe "GET index" do
    it "assigns all accounts as @accounts" do
      # Pass a block to stub to specify the return value
      Account.stub(:all) { [mock_account] }
      get :index
      # Assertions are also made against the mock
      assigns(:accounts).should eq([mock_account])
    end
  end

  describe "GET show" do
    it "assigns the requested account as @account" do
      Account.stub(:find).with("37") { mock_account }
      get :show, :id => "37"
      assigns(:account).should be(mock_account)
    end
  end

  describe "GET new" do
    it "assigns a new account as @account" do
      Account.stub(:new) { mock_account }
      get :new
      assigns(:account).should be(mock_account)
    end
  end
end