Authorship

Regarding authorship of Decidim resources/entities, there are three concerns involved directly:

Decidim::ActsAsAuthor: which defines how an author should behave.
Decidim::Authorable and Decidim::Coauthorable: which define the behaviour around who authored a resource.

But the presenters for the classes including ActsAsAuthor should also behave in a certain manner. This has been resolved using the duck typing strategy (remember, if it quacks as as duck, then it is a duck). Thus, there is not any interface declaring which are the methods to be implemented by the presenter of an author. Anyway one of the OfficialAuthorPresenters may be used as a reference.