I've gotten totally fed up with the amount of clicking I need to do
every time a test fails in CI to find out what exactly failed. The
output that meson gives in its main output is completely useless
currently.

Subject: [PATCH v1 1/5] meson: Include pg_regress diffs in meson output

@@ -1521,22 +1523,40 @@ results_differ(const char testname, const char resultsfile, const char *defaul
* append to the diffs summary file.
*/

- / Write diff header /
- difffile = fopen(difffilename, "a");
+ difffile = fopen(difffilename, "a+");
if (difffile)
{
+ fseek(difffile, 0, SEEK_END);
+ startpos = ftell(difffile);
fprintf(difffile,
"diff %s %s %s\n",
prettydiffopts, bestexpectfile, resultsfile);
+ fflush(difffile);
+
+ / Run diff /
+ snprintf(cmd, sizeof(cmd),

+ "diff %s \"%s\" \"%s\" >> \"%s\"",

+ prettydiffopts, bestexpectfile, resultsfile, difffilename);
+ run_diff(cmd, difffilename);
+
+ / Emit diff as TAP diagnostics if requested /
+ if (print_diffs)
+ {
+ char line[1024];
+
+ fseek(difffile, startpos, SEEK_SET);
+ while (fgets(line, sizeof(line), difffile))
+ {
+ size_t len = strlen(line);
+

+ if (len > 0 && line[len - 1] == '\n')

+ line[len - 1] = '\0';
+ diag("%s", line);
+ }
+ }
fclose(difffile);
}

From c1db07a8bba54e6b903766585f1b521ef526de12 Mon Sep 17 00:00:00 2001

From: Jelte Fennema-Nio <postgres@jeltef.nl>

Date: Mon, 26 Jan 2026 09:09:11 +0100
Subject: [PATCH v1 2/5] perl tap: Show failed command output

This adds the output of failed commands to the TAP output. Before a
failed libpq_pipeline test would look like this:

Failed test 'libpq_pipeline cancel'
at /home/jelte/work/postgres-3/src/test/modules/libpqpipeline/t/001libpq_pipeline.pl line 55.

Now you can actually see the reason of the failure:

Failed test 'libpq_pipeline cancel'
at /home/jelte/work/postgres-3/src/test/modules/libpqpipeline/t/001libpq_pipeline.pl line 55.
----- command failed -----
libpqpipeline -r 700 cancel port=14309 host=/tmp/htMib451qD dbname='postgres' maxprotocol_version=latest
--------- stderr ---------
test cancellations...
libpq_pipeline:315: unexpected number of rows received: 1
--------------------------
---
src/test/perl/PostgreSQL/Test/Utils.pm | 36 +++++++++++++++++++++++---
1 file changed, 32 insertions(+), 4 deletions(-)

diff --git a/src/test/perl/PostgreSQL/Test/Utils.pm b/src/test/perl/PostgreSQL/Test/Utils.pm
index ff843eecc6e..bd1e981c6f0 100644
--- a/src/test/perl/PostgreSQL/Test/Utils.pm
+++ b/src/test/perl/PostgreSQL/Test/Utils.pm
@@ -955,8 +955,22 @@ sub command_ok
{
local $Test::Builder::Level = $Test::Builder::Level + 1;
my ($cmd, $testname) = @;
- my $result = run_log($cmd);
- ok($result, $test_name);
+ # Doesn't rely on detecting end of file on the file descriptors,
+ # which can fail, causing the process to hang, notably on Msys
+ # when used with 'pg_ctl start'

+ my $stdoutfile = File::Temp->new();
+ my $stderrfile = File::Temp->new();

+ my $result = IPC::Run::run $cmd, '>' => $stdoutfile, '2>' => $stderrfile;

+ ok($result, $test_name) or do
+ {
+ my $stdout = slurp_file($stdoutfile);
+ my $stderr = slurp_file($stderrfile);
+ diag("----- command failed -----");
+ diag(join(" ", @$cmd));
+ diag("--------- stdout ---------"), diag($stdout) if $stdout;
+ diag("--------- stderr ---------"), diag($stderr) if $stderr;
+ diag("--------------------------");
+ };

return;
}

@@ -972,8 +986,22 @@ sub command_fails
{
local $Test::Builder::Level = $Test::Builder::Level + 1;
my ($cmd, $testname) = @;
- my $result = run_log($cmd);
- ok(!$result, $test_name);
+ # Doesn't rely on detecting end of file on the file descriptors,
+ # which can fail, causing the process to hang, notably on Msys
+ # when used with 'pg_ctl start'

+ my $stdoutfile = File::Temp->new();
+ my $stderrfile = File::Temp->new();

+ my $result = IPC::Run::run $cmd, '>' => $stdoutfile, '2>' => $stderrfile;

+ ok(!$result, $test_name) or do
+ {
+ my $stdout = slurp_file($stdoutfile);
+ my $stderr = slurp_file($stderrfile);
+ diag("-- command succeeded unexpectedly --");
+ diag(join(" ", @$cmd));
+ diag("-------------- stdout --------------"), diag($stdout) if $stdout;
+ diag("-------------- stderr --------------"), diag($stderr) if $stderr;
+ diag("------------------------------------");
+ };

From c88f1fbf6462da56a1f0739dd83a6284d6bdd389 Mon Sep 17 00:00:00 2001

From: Jelte Fennema-Nio <postgres@jeltef.nl>

Date: Mon, 26 Jan 2026 09:32:15 +0100
Subject: [PATCH v1 3/5] perl tap: Show die reason in TAP output
...
diff --git a/src/test/perl/PostgreSQL/Test/Utils.pm b/src/test/perl/PostgreSQL/Test/Utils.pm
index bd1e981c6f0..df328d0f571 100644
--- a/src/test/perl/PostgreSQL/Test/Utils.pm
+++ b/src/test/perl/PostgreSQL/Test/Utils.pm
@@ -206,6 +206,14 @@ INIT
# test may still fail, but it's more likely to report useful facts.
$SIG{PIPE} = 'IGNORE';

+ # Emit die messages as TAP diagnostics so they appear in test output.
+ $SIG{DIE} = sub {
+ return if $^S; # Ignore dies inside eval
+ my $msg = shift;
+ chomp $msg;
+ diag("die: $msg");
+ };
+

"Tests were run but no plan was declared and done_testing() was not seen."

From a6b324678293d65f3a417b8f66889b3f3f6a9c29 Mon Sep 17 00:00:00 2001

From: Jelte Fennema-Nio <postgres@jeltef.nl>

Date: Mon, 26 Jan 2026 10:04:44 +0100
Subject: [PATCH v1 4/5] perl tap: Include caller in die messages of psql

This way by looking at the error output you can actually figure out
where it occured, instead of just knowing that is in the very often
called psql function.

local $Test::Builder::Level = $Test::Builder::Level + 1;