Backporting PostgresNode.pm

Hi all

Tom mentioned in "9.6 TAP tests and extensions" [1] that

"[I]n the past we've often regretted it when we failed
to back-patch TAP infrastructure fixes all the way back to 9.4."

So maybe we should do just that? Backpatch to add PostgresNode.pm,
RecursiveCopy.pm, and the changes to TestLib.pm, as well as
src/test/recovery/* ?

TAP tests aren't run or enabled by default anyway, so it'd only affect
sites that --enable-tap-tests and run them.

The backport to 9.5 pretty much consists of "cp", with a trivial
change of wal_level = 'replica' to wal_level = 'hot_standby' in
PostgresNode.pm . Also have to delete the
multiple-synchronous-standbys tests from t/007_sync_rep.pl .

The existing TAP tests, which in 9.5 are:

./src/bin/initdb/t
./src/bin/pg_basebackup/t
./src/bin/pg_config/t
./src/bin/pg_controldata/t
./src/bin/pg_ctl/t
./src/bin/pg_rewind/t
./src/bin/pgbench/t
./src/bin/scripts/t
./src/test/ssl/t

all need some updates to use PostgresNode.pm since
configure_hba_for_replication(), start_test_server(),
stop_test_server() etc have gone away. But conversion looks pretty
simple, especially with the help of a compat wrapper in TestLib.pm .

If folks think this is a good idea I can do the compat wrapper for the
existing tests and submit patches. I've got src/test/recovery running
happily for 9.5 already.

[1] https://www.postgresql.org/message-id/6710.1473775370@sss.pgh.pa.us

--
Craig Ringer http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services