From: Tom Lane <tgl@sss.pgh.pa.us>
To: J F <jonathanfoo0523@gmail.com>
cc: pgsql-hackers@lists.postgresql.org
Subject: Re: Contributing test cases to improve coverage
In-reply-to: <CAEFLKGhVEP4_N4T4KQ75av7CEJreJpY1j2T+Dxq96dyJ1khBhg@mail.gmail.com>
References: <CAEFLKGhVEP4_N4T4KQ75av7CEJreJpY1j2T+Dxq96dyJ1khBhg@mail.gmail.com>
Comments: In-reply-to J F <jonathanfoo0523@gmail.com>
	message dated "Wed, 12 Jun 2024 17:44:29 +0100"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <1508709.1718216567.1@sss.pgh.pa.us>
Date: Wed, 12 Jun 2024 14:22:47 -0400
Message-ID: <1508710.1718216567@sss.pgh.pa.us>
Archived-At: <https://www.postgresql.org/message-id/1508710.1718216567%40sss.pgh.pa.us>
Precedence: bulk

J F <jonathanfoo0523@gmail.com> writes:
> For postgres, I am looking at adding test cases to test suite in
> test/src/regress/. I have gone through (a)-(e), and managed to produced
> some test cases. As an example, I claim the test case
> ```
> CREATE RECURSIVE VIEW a(b) AS SELECT'' ;
> SELECT FROM a WHERE NULL;
> ```
> could kill the following mutation at optimizer/plan/setrefs.c, 502:5--502:33
> Original binary operator expression:
> ```
> rte->rtekind == RTE_SUBQUERY
> ````
> Replacement expression:
> ```
> (rte->rtekind) >= RTE_SUBQUERY
> ```

I am quite confused about what is the point of this.  You have not
found any actual bug, nor have you demonstrated that this test case
could discover a likely future bug that wouldn't be detected another
way.  Moreover, it seems like the process would lead to some very
large number of equally marginal test cases.  We aren't likely to
accept such a patch, because we are concerned about keeping down the
runtime of the test suite.

			regards, tom lane