I think this test is going to break on nonstandard block sizes. While we don't promise that all tests work on such installs (particularly planner ones), it seems fairly easy to cope with this one -- just use a record size expressed as a fraction of current_setting('block_size'). So instead of "1024" you'd write current_setting('block_size') / 8. And then display the relation size in terms of pages, not bytes, so divide pg_relation_size by block size.
(I see that there was already a motion for this, but was dismissed because of lack of interest.) -- Álvaro Herrera https://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services