Thread: BUG #18960: Mistake in test test_simple_pipeline (libpq_pipeline.c)

The following bug has been logged on the website:

Bug reference:      18960
Logged by:          Dmitry Kovalenko
Email address:      d.kovalenko@postgrespro.ru
PostgreSQL version: 18beta1
Operating system:   any
Description:

Hello,
Please look at these test lines in
src/test/modules/libpq_pipeline/libpq_pipeline.c 1657-1662:

https://github.com/postgres/postgres/blob/c2e2589ab969eb802493191c79de844bf7dc3a6e/src/test/modules/libpq_pipeline/libpq_pipeline.c#L1657-L1662
---
        PQclear(res);
        res = NULL;
        if (PQgetResult(conn) != NULL)
                pg_fatal("PQgetResult returned something extra after
pipeline end: %s",
                                 PQresStatus(PQresultStatus(res)));
---
You forgot to assign res:
---
        PQclear(res);
        res = NULL;
        if ((res = PQgetResult(conn)) != NULL)
                pg_fatal("PQgetResult returned something extra after
pipeline end: %s",
                                 PQresStatus(PQresultStatus(res)));
---
Thanks&Regards,
Dmitry Kovalenko
PostgresPro, Russia.

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/c2e2589ab969eb802493191c79de844bf7dc3a6e/src/test/modules/libpq_pipeline/libpq_pipeline.c#L1657-L1662
> ---
>         PQclear(res);
>         res = NULL;
>         if (PQgetResult(conn) != NULL)
>                 pg_fatal("PQgetResult returned something extra after
> pipeline end: %s",
>                                  PQresStatus(PQresultStatus(res)));
> ---
> You forgot to assign res:
> ---
>         PQclear(res);
>         res = NULL;
>         if ((res = PQgetResult(conn)) != 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