Skip psql's TAP test for query cancellation entirely on Windows

This changes 020_cancel.pl so as the test is entirely skipped on
Windows.  This test was already doing nothing under WIN32, except
initializing and starting a node without using it so this shaves a few
test cycles.

Author: Yugo NAGATA
Reviewed-by: Fabien Coelho
Discussion: https://postgr.es/m/20230810125935.22c2922ea5250ba79358965b@sraoss.co.jp
Backpatch-through: 15

src/bin/psql/t/020_cancel.pl

@@ -9,72 +9,72 @@ use PostgreSQL::Test::Utils;
 use Test::More;
 use Time::HiRes qw(usleep);
 
-my $tempdir = PostgreSQL::Test::Utils::tempdir;
-
-my $node = PostgreSQL::Test::Cluster->new('main');
-$node->init;
-$node->start;
-
 # Test query canceling by sending SIGINT to a running psql
 #
 # There is, as of this writing, no documented way to get the PID of
 # the process from IPC::Run.  As a workaround, we have psql print its
 # own PID (which is the parent of the shell launched by psql) to a
 # file.
-SKIP:
+if ($windows_os)
 {
-	skip "cancel test requires a Unix shell", 2 if $windows_os;
-
-	local %ENV = $node->_get_env();
-
-	my ($stdin, $stdout, $stderr);
-
-	# Test whether shell supports $PPID.  It's part of POSIX, but some
-	# pre-/non-POSIX shells don't support it (e.g., NetBSD).
-	$stdin = "\\! echo \$PPID";
-	IPC::Run::run([ 'psql', '-X', '-v', 'ON_ERROR_STOP=1' ],
-		'<', \$stdin, '>', \$stdout, '2>', \$stderr);
-	$stdout =~ /^\d+$/ or skip "shell apparently does not support \$PPID", 2;
-
-	# Now start the real test
-	my $h = IPC::Run::start([ 'psql', '-X', '-v', 'ON_ERROR_STOP=1' ],
-		\$stdin, \$stdout, \$stderr);
-
-	# Get the PID
-	$stdout = '';
-	$stderr = '';
-	$stdin = "\\! echo \$PPID >$tempdir/psql.pid\n";
-	pump $h while length $stdin;
-	my $count;
-	my $psql_pid;
-	until (
-		-s "$tempdir/psql.pid"
-		  and ($psql_pid =
-			PostgreSQL::Test::Utils::slurp_file("$tempdir/psql.pid")) =~
-		  /^\d+\n/s)
-	{
-		($count++ < 100 * $PostgreSQL::Test::Utils::timeout_default)
-		  or die "pid file did not appear";
-		usleep(10_000);
-	}
-
-	# Send sleep command and wait until the server has registered it
-	$stdin = "select pg_sleep($PostgreSQL::Test::Utils::timeout_default);\n";
-	pump $h while length $stdin;
-	$node->poll_query_until('postgres',
-		q{SELECT (SELECT count(*) FROM pg_stat_activity WHERE query ~ '^select pg_sleep') > 0;}
-	) or die "timed out";
-
-	# Send cancel request
-	kill 'INT', $psql_pid;
-
-	my $result = finish $h;
-
-	ok(!$result, 'query failed as expected');
-	like(
-		$stderr,
-		qr/canceling statement due to user request/,
-		'query was canceled');
+	plan skip_all => "cancel test requires a Unix shell";
 }
 
+my $tempdir = PostgreSQL::Test::Utils::tempdir;
+
+my $node = PostgreSQL::Test::Cluster->new('main');
+$node->init;
+$node->start;
+
+local %ENV = $node->_get_env();
+
+my ($stdin, $stdout, $stderr);
+
+# Test whether shell supports $PPID.  It's part of POSIX, but some
+# pre-/non-POSIX shells don't support it (e.g., NetBSD).
+$stdin = "\\! echo \$PPID";
+IPC::Run::run([ 'psql', '-X', '-v', 'ON_ERROR_STOP=1' ],
+	'<', \$stdin, '>', \$stdout, '2>', \$stderr);
+$stdout =~ /^\d+$/ or skip "shell apparently does not support \$PPID", 2;
+
+# Now start the real test
+my $h = IPC::Run::start([ 'psql', '-X', '-v', 'ON_ERROR_STOP=1' ],
+	\$stdin, \$stdout, \$stderr);
+
+# Get the PID
+$stdout = '';
+$stderr = '';
+$stdin = "\\! echo \$PPID >$tempdir/psql.pid\n";
+pump $h while length $stdin;
+my $count;
+my $psql_pid;
+until (
+	-s "$tempdir/psql.pid"
+	  and
+	  ($psql_pid = PostgreSQL::Test::Utils::slurp_file("$tempdir/psql.pid"))
+	  =~ /^\d+\n/s)
+{
+	($count++ < 100 * $PostgreSQL::Test::Utils::timeout_default)
+	  or die "pid file did not appear";
+	usleep(10_000);
+}
+
+# Send sleep command and wait until the server has registered it
+$stdin = "select pg_sleep($PostgreSQL::Test::Utils::timeout_default);\n";
+pump $h while length $stdin;
+$node->poll_query_until('postgres',
+	q{SELECT (SELECT count(*) FROM pg_stat_activity WHERE query ~ '^select pg_sleep') > 0;}
+) or die "timed out";
+
+# Send cancel request
+kill 'INT', $psql_pid;
+
+my $result = finish $h;
+
+ok(!$result, 'query failed as expected');
+like(
+	$stderr,
+	qr/canceling statement due to user request/,
+	'query was canceled');
+
 done_testing();