Mock Models and Stubbing for RSpec Controller Tests

Question

I'm testing the create method on a controller for my Viewings model with RSpec. I am trying to create a mock viewing model to minimize calls to my database, stubbing out its new and save methods and returning the appropriate values to test whether the logic of my controller is working:

describe 'POST #create' do
    let(:office_listing) { create(:office_listing) }
    let(:viewing) { mock_model(Viewing).as_null_object }
····
    before do·
      Viewing.stub(:new).and_return(viewing)
    end

    describe 'with valid attributes' do
      it 'saves the viewing' do·
        Viewing.any_instance.stub(:save).and_return(true)
        viewing.should_receive(:save)
        post :create, office_listing_id: office_listing.id
      end
    end

    describe 'with invalid attributes' do
      it 'fails and renders a failure message' do
        Viewing.any_instance.stub(:save).and_return(false)
        viewing.should_receive(:save)
        post :create, :office_listing_id => office_listing.id
        assigns(:failure_message).should_not be_nil
      end
    end
  end
end

here is my controller code:

def create
    @viewing = Viewing.new(params[:viewing])
    @viewing.broker = current_broker
    @viewing.office_listing = params[:office_listing_id]

    p @viewing.save

    if @viewing && @viewing.save == true
      respond_to do |format|
        format.js
        format.html { redirect_to root_path }
      end
    else
      respond_to do |format|
        @failure_message = "Unable to create viewing."
        format.js
        format.html { redirect_to root_path }
      end
    end
  end
end

The problem is that, even though I have stubbed out save to return true or false depending on the test I am in, it always returns a viewing object, which leads me to believe that the stubbing isn't working and the controller is treating my mock object as a real object, making a database call when I call .save. Do I need to be using a class other than Viewing to stub out the method? Should I just be calling viewing.stub instead of Viewing.any_instance? Actually I think typing that may have answered my own question, but I'd still like to hear anyone's thoughts on the issue.

Pierre-Louis Gottfrois Pierre-Louis Gottfrois · Accepted Answer · 2013-08-03T19:46:35

You can't use both

Viewing.any_instance.stub(:save)

and

viewing.should_receive(:save)

The first one is use for control flow, whereas the second one is used to test something.

You should do:

let!(:viewing) { Viewing.new } # no lazy load, executed right away, no need to mock

def action
  post :create, office_listing_id: office_listing.id
end

before do
  Viewing.stub(:new).and_return(viewing)
end

it "calls save" do
  expect(viewing).to receive(:save).and_return(true)
  action
end

Mock Models and Stubbing for RSpec Controller Tests

1 Answers