returning ref cursor

Please let me know what's wrong with below code

CREATE LANGUAGE plpgsql;
create or replace FUNCTION test_cu( p_cursor REFCURSOR) returns REFCURSOR
AS $procedure$
BEGIN
open p_cursor FOR
select * from test;

RETURN p_cursor;
END; $procedure$
LANGUAGE plpgsql;

create or replace FUNCTION test_call()
RETURNS VOID
AS $procedure$
DECLARE
c_cursor REFCURSOR;
r_emp test%rowtype;
BEGIN
PERFORM test_cu(c_cursor);
loop
fetch c_cursor into r_emp;
exit when NOT FOUND;
RAISE NOTICE '%',r_emp.aaa;
end loop;
close c_cursor;
RETURN;
END; $procedure$
LANGUAGE plpgsql;

SELECT test_call();

When I execute above code I got below error

ERROR: cursor variable "c_cursor" is null
CONTEXT: PL/pgSQL function "test_call" line 7 at FETCH

********** Error **********

ERROR: cursor variable "c_cursor" is null
SQL state: 22004
Context: PL/pgSQL function "test_call" line 7 at FETCH

Thanks,
Ravi Katkar