Make PostgresNode.pm's poll_query_until() more chatty about failures.

tglsfdc · tglsfdc · commit 0a576cd2a9ab · 2018-10-16T12:27:33.000-04:00
Reporting only the stderr is unhelpful when the problem is that the server output we're getting doesn't match what was expected. So we should report the query output too; and just for good measure, let's print the query we used and the output we expected. Back-patch to 9.5 where poll_query_until was introduced. Discussion: https://postgr.es/m/17913.1539634756@sss.pgh.pa.us
diff --git a/src/test/perl/PostgresNode.pm b/src/test/perl/PostgresNode.pm
@@ -1257,9 +1257,18 @@ sub poll_query_until
 		$attempts++;
 	}
 
-	# The query result didn't change in 180 seconds. Give up. Print the stderr
-	# from the last attempt, hopefully that's useful for debugging.
-	diag $stderr;
+	# The query result didn't change in 180 seconds. Give up. Print the
+	# output from the last attempt, hopefully that's useful for debugging.
+	chomp($stderr);
+	$stderr =~ s/\r//g if $TestLib::windows_os;
+	diag qq(poll_query_until timed out executing this query:
+$query
+expecting this output:
+$expected
+last actual query output:
+$stdout
+with stderr:
+$stderr);
 	return 0;
 }
 
