Can i have one foreign key to both parent and it's childs in postgresql?

I want to have a foreign key to reference table and it's children. Here's how I tried and failed:

CREATE TABLE parent ( id serial, CONSTRAINT parent_pk PRIMARY KEY(id));CREATE TABLE child (  val text,  constraint child_pk PRIMARY KEY(id)) INHERITS(parent);CREATE TABLE test (  id serial,  foreign_id bigint REFERENCES parent(id),  constraint testpk PRIMARY KEY (id))

Lets say we have such data:

parent:|id| +--+|1 | --public.parent oid|2 | --public.child oidchild:|id|val|+--+---+|2 |'a'| --public.child oid

what i whant to acheive is this:

test:|id|foreign_id|+--+----------+|1 | 1        | --(from public.parent table)|2 | 2        | --(from public.child table)

is there a good workaround here?