[Checkout] Shipping fee not updated after editing order

[drummer83]

Description

This was found while testing #12880 and might be related to #11360.

If an order is updated by the customer after reaching step 3 of the checkout already, then the shipping fees will only be updated on the order summary page, but it will not be updated on the order confirmation screen and in the email. This results in an incorrect order total (on confirmation screen and in the email).

Expected Behavior

After updating the order, the order total on the order summary page should match the order total on the order confirmation page.

Actual Behaviour

After updating the order, the order total on the order summary page is different than the order total on the order confirmation page. This is because the shipping fee is not updated along with the order.

Steps to Reproduce

1. Create a shipping method with a fee using the flat percent calculator.
2. As a customer start an order with that shipping method and proceed to step three (order summary) of the checkout but don't complete the order.
3. Take note of the order total and the shipping fee.
4. Continue shopping, i.e. click on the shop's name next to the cart icon in the top right corner.
5. Add one or more products to your cart.
6. Click checkout again - you should land on step 3 (order summary directly).
7. Take note of the order total and the shipping fee - both should be updated correctly, including your added products.
8. Complete the order.
9. Compare the numbers of order total and shipping fee again. The shipping fee is the old value before adding products and the order total is less than on the order summary page. ❌

Animated Gif/Screenshot

Order summary page after updating the order:

Order confirmation page after completing the order:

Workaround

Severity

bug-s2: a non-critical feature is broken, no workaround

Your Environment

• Version used:
• Browser name and version:
• Operating System and version (desktop or mobile):

Possible Fix

[rioug]

Similar to #12880 but the cause is different,
Shipment fees are recalculated in various places ,
Spree::Order :

openfoodnetwork/app/models/spree/order.rb

Lines 516 to 523 in f54552f

	def update_shipping_fees!
	shipments.each do |shipment|
	next if shipment.shipped?
	update_adjustment! shipment.fee_adjustment if shipment.fee_adjustment
	save_or_rescue_shipment(shipment)
	end
	end

Triggered by this callback

openfoodnetwork/app/models/spree/order.rb

Line 105 in f54552f

before_save :update_shipping_fees!, if: :complete?

Spree::Shipment :

openfoodnetwork/app/models/spree/shipment.rb

Lines 278 to 291 in f54552f

	def ensure_correct_adjustment
	if fee_adjustment
	fee_adjustment.originator = shipping_method
	fee_adjustment.label = adjustment_label
	fee_adjustment.amount = selected_shipping_rate.cost if fee_adjustment.open?
	fee_adjustment.save!
	fee_adjustment.reload
	elsif shipping_method
	shipping_method.create_adjustment(adjustment_label,
	self,
	true,
	"open")
	reload # ensure adjustment is present on later saves
	end

Triggered by this callback

openfoodnetwork/app/models/spree/shipment.rb

Line 20 in f54552f

after_save :ensure_correct_adjustment, :update_adjustments

ensure_correct_adjustment is actually wrong , on line 282 it used selected_shipping_rate.cost instead of using the calculator linked to the originator.
We'll need to reassess if we need this ensure_correct_adjustment or fix it to update the adjustment as expected.