Question

I have the following rspec test:

def valid_attributes
  { "product_id" => "1" }
end

describe "POST create" do
  describe "with valid params" do
    it "creates a new LineItem" do
      expect {
        post :create, {:line_item => valid_attributes}, valid_session #my valid_session is blank
      }.to change(LineItem, :count).by(1)
    end

Which fails with this error:

1) LineItemsController POST create with valid params redirects to the created line_item
   Failure/Error: post :create, {:line_item => valid_attributes}, valid_session
   ActiveRecord::RecordNotFound:
     Couldn't find Product without an ID
     # ./app/controllers/line_items_controller.rb:44:in `create'
     # ./spec/controllers/line_items_controller_spec.rb:87:in `block (4 levels) in <top (required)>'

This is my controller’s create action:

def create
  @cart = current_cart
  product = Product.find(params[:product_id])
  @line_item = @cart.line_items.build(:product => product)

  respond_to do |format|
    if @line_item.save
      format.html { redirect_to @line_item.cart, notice: 'Line item was successfully created.' }
      format.json { render json: @line_item.cart, status: :created, location: @line_item }
    else
      format.html { render action: "new" }
      format.json { render json: @line_item.errors, status: :unprocessable_entity }
    end
  end
end

As you can see, my action expects a product_id from the request’s params object. How should I work this product_id into my rspec test?

I’ve tried placing this before statement:

before(:each) do
    ApplicationController.any_instance.stub(:product).and_return(@product = mock('product'))
  end

. . . but it changes nothing. I am missing some rspec concept here somewhere.

Answer 1

I ended up resolving my issue by using a fixture instead of attempting to mock the solution as suggested in another answer.

The reason for this is that the controller does the query to get information from the database: product = Product.find(params[:product_id]) and I found a fixture-based solution was quicker to resolve my problem than one using a mock and I could not figure out how to stub the query quickly (the fixtures also help with another test on the controller so it eventually helped anyway.

For reference:

I referenced my fixture with this line toward the top of the test: fixtures :products

I changed my test to:

describe "POST create" do
  describe "with valid params" do
    it "creates a new LineItem" do
      expect {
          post :create, :product_id => products(:one).id
       }.to change(LineItem, :count).by(1)
    end

And here is my fixture file, products.yml:

one:
    name: FirstProduct
    price: 1.23

two:
    name: SecondProduct
    price: 4.56