gistfile1.rb

 describe '#download_invoice' do
  
    let(:user) { Factory.create(:user) }


    context 'as a user with a valid token' do
      
      before :each do
        stub.proxy(User).where(anything)
        stub(User).where(:api_token => 'token') { [ user ] }
        @params = {:id => 1, :token => 'token'}
        @invoice = Factory(:invoice)
        mock(Invoice).find(1) { @invoice }
      end

      context "invoice exists" do
        before :each do
          @invoice.to_pdf
          mock(File).exists?(anything) { true }
        end

        it 'should not call to_pdf on the invoice' do
          dont_allow(@invoice).to_pdf
          get :download_invoice, @params
        end
      end

      context "invoice does not exist" do
        before :each do
          mock(File).exists?(anything) { false }
        end

        it 'should not call to_pdf on the invoice' do
          @invoice.should_receive(:to_pdf)
          get :download_invoice, @params
        end

      end
      it 'should be successful' do
        get :download_invoice, @params
        response.should be_successful
      end
      
      it 'should send back a pdf' do
        get :download_invoice, @params
        response.content_type.should == 'text/pdf'
      end

      it 'should send the correct file' do
        get :download_invoice, @params
        response.headers["Content-Disposition"].should == "attachment; filename=\"invoice_#{@invoice.id}.pdf\""
      end
    end
  end