Update action rspec

Question

this is controller

def update
    respond_to do |format|
      if @line_item.update(line_item_params)
        format.html { redirect_to @line_item, notice: 'Line item was successfully updated.' }
        format.json { render :show, status: :ok, location: @line_item }
      else
        format.html { render :edit }
        format.json { render json: @line_item.errors, status: :unprocessable_entity }
      end
    end
  end

private
def line_item_params
      params.require(:line_item).permit(:product_id, :cart_id) #Check this
    end

Test case I have written in order to fail such that it renders edit

    context "with invalid parameters" do
      it "renders a successful response (i.e. to display the 'edit' template)" do
        order = create(:order, user_id: user.id, email: user.email)

        category = create(:category)
        product = create(:product, category_id: category.id)
        cart = create(:cart)

        line_item = create(:line_item,order_id: order.id,product_id: product.id,cart_id:cart.id)
        line_item.product_id = 1
        patch line_item_url(line_item), params: { line_item: { product_id:line_item.product_id}}
        expect(response).to render_template(:edit)

      end
    end

I am getting an error below:

     Failure/Error: if @line_item.update(line_item_params)
     
     ActiveRecord::InvalidForeignKey:
       PG::ForeignKeyViolation: ERROR:  insert or update on table "line_items" violates foreign key constraint "fk_rails_11e15d5c6b"
       DETAIL:  Key (product_id)=(1) is not present in table "products".

It is not going to the else part.

I Am not able to check with the invalid parameters. Please let me know Thank you

Answer 1

Well, every time you run this script, database is truncated or deleted (depends on your gem environment), that means that PK (primary key) for table every time incremented ++. So line_item.product_id = 1 it is totally invalid, cause 1 ID could be available during very first running of the test spec.

Change to dynamic assignment, and you will get rid of that error.

...
other_product = create(:product, category_id: category.id)

line_item = create(:line_item, order_id: order.id, product_id: product.id, cart_id: cart.id)
line_item.product_id = other_product.id # or any other id, that you are creating during this spec, but not just simple integer
...