Shipment transition callbacks being skipped

[skukx]

Assume the below setup:

Spree::Shipment.class_eval do
  state_machine.after_transition to: :ready, do: :my_method

  def my_method
    puts 'my_method called'
  end
end

After an order is completed, Spree::Order#finalize! gets called.
See

solidus/core/app/models/spree/order.rb

Lines 409 to 412 in 86501e4

	shipments.each do |shipment|
	shipment.update!(self)
	shipment.finalize!
	end

If the order is paid for then these shipments will be updated to ready. The problem is that this update skips callbacks so Spree::Shipment#my_method will not be called even though the shipment has transitioned to a state of ready.

Expected behavior would be that when the order moved to complete and updates the shipments. Each shipment that is updated to another state will create a transition event for that state change.

Solidus 2.2
Happens in Core Solidus

See #2065 for specs recreating behavior

[mamhoff]

This is a can of worms. We explicitly don't run the Shipment state machine, and rather determine the shipment's state by its attributes for performance and complexity reasons (the order and shipment state machine interact in strange ways).

You're right in that we should do one of two things: Either remove the shipment state machine entirely, or actually use it.