From: Tom Lane <tgl@sss.pgh.pa.us>
To: d.kovalenko@postgrespro.ru
cc: pgsql-bugs@lists.postgresql.org
Subject: Re: BUG #18960: Mistake in test test_simple_pipeline
 (libpq_pipeline.c)
In-reply-to: <18960-09cd4a5100152e58@postgresql.org>
References: <18960-09cd4a5100152e58@postgresql.org>
Comments: In-reply-to PG Bug reporting form <noreply@postgresql.org>
	message dated "Wed, 18 Jun 2025 19:25:04 -0000"
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Date: Wed, 18 Jun 2025 17:09:03 -0400
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PG Bug reporting form <noreply@postgresql.org> writes:
> Please look at these test lines in
> src/test/modules/libpq_pipeline/libpq_pipeline.c 1657-1662:
> https://github.com/postgres/postgres/blob/c2e2589ab969eb802493191c79de84=
4bf7dc3a6e/src/test/modules/libpq_pipeline/libpq_pipeline.c#L1657-L1662
> ---
>         PQclear(res);
>         res =3D NULL;
>         if (PQgetResult(conn) !=3D NULL)
>                 pg_fatal("PQgetResult returned something extra after
> pipeline end: %s",
>                                  PQresStatus(PQresultStatus(res)));
> ---
> You forgot to assign res:
> ---
>         PQclear(res);
>         res =3D NULL;
>         if ((res =3D PQgetResult(conn)) !=3D NULL)
>                 pg_fatal("PQgetResult returned something extra after
> pipeline end: %s",
>                                  PQresStatus(PQresultStatus(res)));

I agree that's wrong ... but looking around, there's a huge amount
of random inconsistency in this test script --- this same simple
task of checking for an expected NULL result is coded several
different ways with varying amounts of detail provided, and
some other places share this same outright bug.

I think it'd be better to make a helper function
"CheckNoMoreResults(conn)", or something along that line,
to shorten and standardize these places.

On the other side of the coin, the explicit tests for a result
*not* being NULL are mostly unnecessary; if the next step is
a check of PQresultStatus, we could just rely on the fact
that PQresultStatus(NULL) returns PGRES_FATAL_ERROR.

			regards, tom lane