For some reason the order objects were stale here when calling order.update! from either a payment or shipment callback, which was overwriting those states as nil on the order.
This new class lets us [Branch by
abstraction](https://www.martinfowler.com/bliki/BranchByAbstraction.html)
by encapsulating an order's balance. As a result, that's the only place
where we need to check the feature toggle, instead of every place where
`#outstanding_balance` is called (quite some). That would be very hard
to review and it'd be more likely to introduce bugs.
What I like about this is that we also managed to group together the
data and logic that we had spread in a few places and have it nicely
encapsulated. So, where we had a number, we'll now have an object.
Once we fully change all `#outstanding_balance` consumers to use this
new abstraction we'll be able to remove the methods this class replaces.
These are: `Spree::Order#outstanding_balance?`,
`Spree::Order#display_oustanding_balance` and
`OrderHelper.outstanding_balance_label`.
This is just the first step. I'll follow this up with a PR per
page/mailer/whatever where we use the balance to replace it with an
instance of `OrderBalance`. That is, splitting up what I explored in
https://github.com/openfoodfoundation/openfoodnetwork/pull/6959 but in
very small and manageable pieces.
We set this value to `true` unconditionally in an initializer, and then check the value in various places via Spree::Config. It's never false, and it's not configurable, so we can just drop it and remove the related conditionals. 🔥
This model concerns helps us put together this related methods. Although
it doesn't provide any encapsulation yet, it makes a bit easier to
consider them all next time we need to change this implementation
somehow. It's a bit of an illusion but it feels like we are making this
God object model a bit smaller.
It also gives more room for documentation that will aid future devs.
The custom RSpec matchers they use raises the following deprecation
warning
```
Using `stub` from rspec-mocks' old `:should` syntax without explicitly enabling the syntax is deprecated. Use the new `:expect` syntax or explicitly enable `:should` instead. Called from /home/runner/work/openfoodnetwork/openfoodnetwork/spec/support/matchers/delegate_matchers.rb:22:in `block (2 levels) in <top (required)>'.
```
It's not worth maintaining those matchers to test such
implementation-related thing. Whether or not any delegations work is
something that will be caught by integration tests or directly stubbing
the collaborator object's methods.
This stems from
https://github.com/openfoodfoundation/openfoodnetwork/pull/6902.
