Promotion eligibility? usage count

[cedum]

When performing the eligibility check for a promotion, the usage limit check should not count the promotable that has been already applied for the promotion.
I suspect the same must be done also when re-computing the amounts in promo actions, otherwise, it sets them to zero.

Here's a test case (I did my best to explain it without letting my brain go into a loop 💥):

• Given I have an active promotion with 1 usage limit
• Given I have a completed order with the promotion above applied
• When I edit and save the promotion' adjustment and the promo has 0 usages left
  • The adjustment is saved as ineligible and amount set to 0
  • The promotion changes to 1 usage left
• When I edit and save again the promotion' adjustment
  • The adjustment is saved as eligible and amount to the promo discount
  • The promotion changes back to "0 usages left"

Rinse and repeat to switch the adjustment to ineligible and back

Reproduced against solidus versions: 2.9.0.alpha and 2.7.1

[loicginoux]

Just checking but was your order completed ? it should only count promotion usage for completed order normally. If it does it with incomplete order, that's something weird indeed.

#promotion model:

    def usage_count
      Spree::Adjustment.eligible.
        promotion.
        where(source_id: actions.map(&:id)).
        joins(:order).
        merge(Spree::Order.complete).
        distinct.
        count(:order_id)
    end

[cedum]

@loicginoux yes, tested it on a completed order (I've updated the issue description to reflect this)

[kennyadsl]

I think you are right, this happens because the eligibility check is done when there are no eligible "usage" left. I think we should add that "usage" to the count somehow to make it work.