Search path & functions in temporary schemas

Hi all,

I was trying to mock a function. So I followed the instructions in this
</messages/by-id/0E379B0D-EEFA-45FB-AC60-23F760B8D338@justatheory.com&gt;
thread.

I created a function with the same name as the existing one in different
schema, and I updated the search path adding that schema at the beginning.

This solution worked with a real schema, but it did not with a temporary
one.

Code working with a real schema:

SHOW SEARCH_PATH; -- public

CREATE OR REPLACE FUNCTION public.get_random_string()

RETURNS TEXT LANGUAGE SQL AS $$
SELECT 'real'::text;
$$;

SELECT get_random_string(); -- real

CREATE SCHEMA mock;

CREATE OR REPLACE FUNCTION mock.get_random_string()
RETURNS TEXT LANGUAGE SQL AS $$
SELECT 'mock'::text;
$$;

SELECT get_random_string(); -- real

SET SEARCH_PATH = mock, public;

SELECT get_random_string(); -- mock

Code not working with a temporary schema:

SHOW SEARCH_PATH; -- public

CREATE OR REPLACE FUNCTION public.get_random_string()

RETURNS TEXT LANGUAGE SQL AS $$
SELECT 'real'::text;
$$;
SELECT get_random_string(); -- real

SELECT nspname FROM pg_namespace WHERE oid = pg_my_temp_schema(); --

pg_temp_12

CREATE OR REPLACE FUNCTION pg_temp_12.get_random_string()

RETURNS TEXT LANGUAGE SQL AS $$
SELECT 'mock'::text;
$$;
SELECT get_random_string(); -- real

SET SEARCH_PATH = pg_temp_12, public;

SELECT get_random_string(); -- real

Is there any way to make this work?

Thanks,
Jose