This implementation is a bit more robust because we don't have to change
any of the "or_later?" methods if we add or remove a new phase.
We could also use metaprogramming to reduce code duplication in these
methods. So far, I've decided to keep the code simple since the
duplication seems reasonable.
Slugs should only be updated on certain conditions, we need a trait that
meets that conditions and the name of the trait passed as a mandatory &
named argument on the sluggable concern
Before Budget.current could return multiple budgets, now there can only
be a single current_budget.
Adding the concept of open, which better reflects what the admin sees
in this page: A tab for open budgets and a tab for finished budgets
When there was only one budget this implementation worked fine
Nowadays there can be multiple budgets, and therefore the definition of
the current_budget has changed. It is no longer a budget that has not
finished, but rather, the last budget created that is not in the
initial drafting phase.
Budgets in the drafting phase are not considered the current_budget,
but rather a budget that is still being prepared and that soon will
become the current_budget
Why:
* Slug must be unique among:
1. Budget slug: among other budgets
2. Group slug: among other groups from its budget
3. Heading slug: among other headings from all the groups from its budget
How:
* Adding checks for all possible scenarios on each model specs
Why:
* Those classes have a slug attribute that needs to be filled
How:
* Just adding the shared example to Budget model spec, and creating the model spec file for Heading and Group to include it as well
