Re: [PATCH] Add regress test for pg_read_all_stats role

- There is no need for the initial DROP ROLE commands as those already
get dropped at the end of the tests.

- There is already rolenames.sql which has a tiny coverage for default
roles, why not just using it?

+-- should fail because regress_role_nopriv has not CONNECT permission
on this db
+SELECT pg_database_size('regression') > 0 AS canread;
+ERROR:  permission denied for database regression
+-- should fail because regress_role_nopriv has not CREATE permission on
this tablespace
+SELECT pg_tablespace_size('pg_global') > 0 AS canread;
+ERROR:  permission denied for tablespace pg_global
Why is that part of a test suite for default roles?

2) is easy to be triggered as a negative test (which fails), less as a
positive test.  In order to make a positive test failure-proof with
installcheck you would need to have a parameter which can be changed by
a superuser at session level which gets updated to a certain value, and
would fail to show for another user, so you could use one which is
GUC_SUPERUSER_ONLY and of category PGC_SUSET, like
session_preload_libraries or dynamic_preload_libraries.  Still that's
pretty restrictive, and would only test one out of the three code paths
available.