describe "check line items before destroy" do
    context "item has no line items" do
      it "destroys item" do
        expect(product.destroy)
      end
    end

    context "item has line items" do
      it "does not destroy item" do
        LineItem.create!(product_id: product.id, cart_id: cart.id, quantity: 1)
        expect(product.destroy)
      end
    end
  end