Allow the order total to be equal to 0

[jibees]

What? Why?

The aim of this PR is to not check the total of an order before going to payment state for an order. This is a side effect of the split checkout: order with total equals to 0 can't go to next step (from details to payment)

• Closes Can't proceed to checkout if order total is equal to 0 (blocked at details step) #10787

What should we test?

• As a producer, sells product at 0
• As a consumer, add this product to cart
• Check that you can order product (with different payment methods), even if total order is equal to 0

Release notes

Changelog Category: User facing changes

The title of the pull request will be included in the release notes.

Dependencies

Documentation updates

[Matt-Yorkley]

Hmmmm... I think there were some technical reasons why various bits of the code don't allow placing an order with a total of zero. Off the top of my head, I think if you have Paypal as the selected payment option it will throw an error if the total is zero and the checkout will fail.

So this might need a little more thinking about how this case is handled and what consequences these changes might have in various parts of the app... 😬

Eg; if a shop only has one payment method enabled and that method is Paypal, you can't check out without a valid payment method being selected, and the only payment method available will not allow checkout. I imagine Stripe is similar.

[jibees]

I think there were some technical reasons why various bits of the code don't allow placing an order with a total of zero.

I agree, but it was somehow possible with the legacy/old checkout ; also I couldn't find any reason of why this code has been placed here, and I thought it was from legacy Spree.

So this might need a little more thinking about how this case is handled and what consequences these changes might have in various parts of the app... 😬

I agree also, that's why I've put this in Draft mode. I'm not sure on how we can check those consequences. Maybe add some specs with that particular case?

[jibees]

Closing here, not sure this is relevant.