Non-promotable items blacklist an entire order

[nspinazz89]

Solidus Version: Master

To Reproduce

1. Mark a product as non-promotable

2. Create a per line item adjustment promotion

3. Create an order with the non-promotable item and promotable items

4. Attempt to apply the coupon in the cart

Current behavior The coupon fails to apply because the order is not eligible for promotion.

Expected behavior This is the correct behavior for a whole order adjustment, but the incorrect behavior for a per line item adjustment. In a per line item adjustment one would expect, that the promotion is applied to each eligible item and the non-eligible item is skipped.

Additional context Interested in alternative solutions, otherwise I will tackle this bug.

[jacobherrington]

This is a bug we found, hopefully we'll have a solution soon, but I'd love to hear of anything people have come up with to solve this elsewhere. 🤠

[jacobherrington]

We are evaluating the approach in #1925. I think this is what I would do in a vacuum, so I want to re-evaluate it and maybe even re-open that PR.

[cedum]

Check @loicginoux comment. I think this might be a better approach to solve this issue instead of the one proposed in the PR#1925.

[kennyadsl]

@jacobherrington @nspinazz89 I'm working with @cedum to another approach to face this problem in #3348, let us know what do you think! This should solve the issue taking into account concerns with applying discounts to non-promotionable items.