Currently this is not something can do. this functionality is there in oracle.
Is this future considering to add? (it would really help for create any test schemas without disturbing current schema. )
I find this to be not all that useful. Current practice is to avoid relying on search_path and, in general, to schema-qualify object references (yes, attaching a local SET search_path to a function works, not sure how it would play out in this context). Performing a dependency and contextual rename of one schema name to another is challenging given all of that, and impossible if the schema name is hard-coded into a function body.
I won't say we wouldn't accept such a patch, but as this isn't exactly a new problem or realization, and the feature doesn't presently exist, that for whatever reasons individuals may have no one has chosen to volunteer or fund such development. I don't even remember seeing a proposal in the past 5 or so years.
