Sylius: Two promotions, where one invalidates the other, makes checkout impossible

[alexrowesoap]

Sylius version affected: 1.2.10

Description
If you have two promotions that both apply for a cart, but when both apply, checkout becomes impossible if one changes the order value as such to invalidate the other.

Steps to reproduce

1. Create a Christmas promotion (this is a demo one)
2. no usage limit
3. Priority 0
4. no date restriction
5. configuration
6. 
   
   • One rule
   
   
7. - - Cart Quantity = 0
8. 
   
   • One action
   
   
9. - - Order Percentage discount = 26
10. Create a New Years promotion (this is also a demo one)
11. usage limit = 10
12. priority 2
13. dates to cover the testing period
14. configuration
15. 
    
    • One rule
    
    
16. - - item total = $100
17. 
    
    • One action
    
    
18. - - order fixed discount = 10
19. Go to the front-end
20. Add 1 $100 item to the basket (20% tax item)
21. Proceed through the checkout to the complete page, and confirm both promotions have applied bringing the total down to $79.92 (free shipping)
22. Click place order
23. You should see an error of "Error. You are no longer eligible for this promotion New Year."

Possible Solution
Not a clue at the moment

[Zales0123]

Thank you, Alex, for the report, we will take a deeper look at it in the nearest future (hopefully) and come up with some solution ideas :)

[Zales0123]

Do you think you could provide a Behat scenario describing this bug? BTW, I suppose Cart Quantity = 0 is not a valid configuration of the promotion rule (unless it's a typo :))

[alexrowesoap]

Hey @Zales0123 I'll see if I can get one together. I think the fixture that generates the test data picks a random integer, but seemingly 0 is valid if set manually.

[Zales0123]

Well, then it should not be for sure, minimum cart quantity should always be 1 :)

[alexrowesoap]

two bugs in one! :joy:
I've never written a behat scenario before, but here goes!

Feature: Ensure promotions work correctly
    In order to checkout successfully with promotions
    As a Visitor
    I want to checkout successfully with promotions

    Background:
        Given the store operates on a single channel in "United States"
        And default tax zone is "US"
        And the store has included in price "US VAT" tax rate of 23% for "Clothes" within the "US" zone
        And the store has a product "PHP T-Shirt" priced at "$100.00"
        And it belongs to "Clothes" tax category
        And there is a promotion "Christmas"
        And the promotion gives "12%" off
        And there is a promotion "New Year"
        And the promotion gives "$10.00" off if item total is greater than "$100.00"
        And the store ships everywhere for free
        And the store allows paying offline

    @ui
    Scenario: Basket with several promotions is able to checkout
        Given I have product "PHP T-Shirt" in the cart
        And I have completed addressing step with email "[email protected]" and "United States" based shipping address
        And I have proceeded order with "Free" shipping method and "Offline" payment
            When I confirm my order
            Then an email with the summary of order placed by "[email protected]" should be sent to him`

[tautelis]

I encountered the same bug on 1.3.* with default fixtures.

After taking a deeper look I found out where the problem hides:
in PromotionProcessor and OrderPromotionIntegrityChecker promotions are applied in different order. Therefore while applying promotion in PromotionProcessor the new_year promotion is applied first and conditions fit. At checkout the OrderPromotionIntegrityChecker applies christmas promotion first which decreased order total so that the new_year promotion is no longer eligible.

To reproduce the bug make sure that christmas promotion drops order total below 100$.

So it is a Bug and not a Potential Bug.

Possible solution

Add the following usort to OrderPromotionIntegrityChecker to be sure that promotion are ordered by priority (same as they are retrieved in PromotionProcessor).

````
// we create a new promotion collection and remove them from cart
// so we can verify with original conditions (without the price being applied before check)

$promotions = $order->getPromotions()->toArray();

usort(
$promotions,
function($promotion1, $promotion2)
{
if ($promotion1->getPriority() == $promotion2->getPriority()) {
return 0;
}

    return ($promotion1->getPriority() > $promotion2->getPriority()) ? -1 : 1;
}

);
````

[stale[bot]]

This issue has been automatically marked as stale because it has not had any recent activity. It will be closed in a week if no further activity occurs. Thank you for your contributions.

[alexrowesoap]

Please do not stale

[tautelis]

Any progress on this important bug? There are moments when it is impossible to checkout due to this.

[loevgaard]

Hi @tautelis

It looks like you created something that looked like a solution. Could you create a PR to demonstrate that it works and create tests for it?

[pamil]

Should be fixed by #10603.