v2-0001-BackgroundPsql-handle-empty-query-results.patch

From 014f42c62659dbf302b85b9265ab0d6b081b08b3 Mon Sep 17 00:00:00 2001
From: Jacob Champion <jacob.champion@enterprisedb.com>
Date: Mon, 8 Jul 2024 10:11:56 -0700
Subject: [PATCH v2 1/4] BackgroundPsql: handle empty query results

There won't be a newline at the end of an empty query result. (Before
this fix, the $banner showed up in the result, leading to confusing
debugging sessions.)

recovery/t/037_invalid_database was relying on the non-empty query
results, so I have switched those cases to use "bare" calls to
query_safe() instead.
---
 src/test/perl/PostgreSQL/Test/BackgroundPsql.pm |  2 +-
 src/test/recovery/t/037_invalid_database.pl     | 12 ++++--------
 2 files changed, 5 insertions(+), 9 deletions(-)

diff --git a/src/test/perl/PostgreSQL/Test/BackgroundPsql.pm b/src/test/perl/PostgreSQL/Test/BackgroundPsql.pm
index 3c2aca1c5d..2760e4bc8d 100644
--- a/src/test/perl/PostgreSQL/Test/BackgroundPsql.pm
+++ b/src/test/perl/PostgreSQL/Test/BackgroundPsql.pm
@@ -223,7 +223,7 @@ sub query
 	$output = $self->{stdout};
 
 	# remove banner again, our caller doesn't care
-	$output =~ s/\n$banner\n$//s;
+	$output =~ s/\n?$banner\n$//s;
 
 	# clear out output for the next query
 	$self->{stdout} = '';
diff --git a/src/test/recovery/t/037_invalid_database.pl b/src/test/recovery/t/037_invalid_database.pl
index 47f524be4c..954c3684a9 100644
--- a/src/test/recovery/t/037_invalid_database.pl
+++ b/src/test/recovery/t/037_invalid_database.pl
@@ -93,13 +93,12 @@ my $bgpsql = $node->background_psql('postgres', on_error_stop => 0);
 my $pid = $bgpsql->query('SELECT pg_backend_pid()');
 
 # create the database, prevent drop database via lock held by a 2PC transaction
-ok( $bgpsql->query_safe(
+$bgpsql->query_safe(
 		qq(
   CREATE DATABASE regression_invalid_interrupt;
   BEGIN;
   LOCK pg_tablespace;
-  PREPARE TRANSACTION 'lock_tblspc';)),
-	"blocked DROP DATABASE completion");
+  PREPARE TRANSACTION 'lock_tblspc';));
 
 # Try to drop. This will wait due to the still held lock.
 $bgpsql->query_until(qr//, "DROP DATABASE regression_invalid_interrupt;\n");
@@ -126,11 +125,8 @@ is($node->psql('regression_invalid_interrupt', ''),
 
 # To properly drop the database, we need to release the lock previously preventing
 # doing so.
-ok($bgpsql->query_safe(qq(ROLLBACK PREPARED 'lock_tblspc')),
-	"unblock DROP DATABASE");
-
-ok($bgpsql->query(qq(DROP DATABASE regression_invalid_interrupt)),
-	"DROP DATABASE invalid_interrupt");
+$bgpsql->query_safe(qq(ROLLBACK PREPARED 'lock_tblspc'));
+$bgpsql->query_safe(qq(DROP DATABASE regression_invalid_interrupt));
 
 $bgpsql->quit();
 
-- 
2.34.1