[NUT-201] Refactor used_by? method for one_use_per_user rule

[KacperMekarski]

This branch is created because of https://spark-solutions.atlassian.net/browse/NUT-201 task.
User can use one_use_per_user promotion many times.
This was tested, but in production user somehow can use the promotion many times.

Actual Behavior

So far condition was checked by looking for same PromotionAction through adjustments:

spree/core/app/models/spree/promotion.rb

Line 196 in 849f985

def used_by?(user, excluded_orders = [])

Although in tests PromotionActions are associated with adjustments as source, in production it occurs that it does not always happen:
irb(main):004:0> user.orders.complete.first.all_adjustments.where(source_type: "Spree::PromotionAction").pluck(:source_id) => [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil] irb(main):005:0> user.orders.complete.second.all_adjustments.where(source_type: "Spree::PromotionAction").pluck(:source_id) => [nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil] irb(main):006:0> user.orders.complete.third.all_adjustments.where(source_type: "Spree::PromotionAction").pluck(:source_id) => []
However, order is always associated:
irb(main):009:0> user.orders.complete.first.promotions.pluck(:id) => [33, 33, 33, 33, 33, 33, 33] irb(main):010:0> user.orders.complete.second.promotions.pluck(:id) => [33] irb(main):011:0> user.orders.complete.third.promotions.pluck(:id) => [33, 33, 33, 33]

Expected behavior

User can use promo code only once

Possible fix

Use promotion to check if it was already used (simpler and based on production data it works).

[squash-labs]

Manage this branch in Squash

Test this branch here: https://spark-solutionsone-use-per-use-tm48z.squash.io

[KacperMekarski]

@przemosk
@piotrpanko
@aplegatt
@szymoniwacz

Happy to hear Your thoughts about that!