Обсуждение: TAP test utility module 'PG_LSN.pm'

Hi all

I'd like to share the attached PG_LSN.pm module that I use when
writing TAP tests. I suggest that it be considered for inclusion in
core.

It defines a Perl datatype PG_LSN with operator support, so you can
write things like

    cmp_ok($got_lsn, "<", $expected_lsn, "testname")

in TAP tests and get sensible results without any concern for LSN
representation details, locale, etc. You can subtract LSNs to get a
byte difference too.

It's small but I've found it handy.

On Tue, Dec 01, 2020 at 12:03:41PM +0800, Craig Ringer wrote:
> I'd like to share the attached PG_LSN.pm module that I use when
> writing TAP tests. I suggest that it be considered for inclusion in
> core.
>
> It defines a Perl datatype PG_LSN with operator support, so you can
> write things like
>
>     cmp_ok($got_lsn, "<", $expected_lsn, "testname")
>
> in TAP tests and get sensible results without any concern for LSN
> representation details, locale, etc. You can subtract LSNs to get a
> byte difference too.

In my experience, any TAP tests making use of LSN operations can just
let the backend do the maths, so I am not much a fan of duplicating
that stuff in a perl module.  Wouldn't it be better to add an
equivalent of your add() function in the backend then?  That could
also get tested in the main regression test suite.
--
Michael

On Tue, 1 Dec 2020 at 13:58, Michael Paquier <michael@paquier.xyz> wrote:
>
> On Tue, Dec 01, 2020 at 12:03:41PM +0800, Craig Ringer wrote:
> > I'd like to share the attached PG_LSN.pm module that I use when
> > writing TAP tests. I suggest that it be considered for inclusion in
> > core.
> >
> > It defines a Perl datatype PG_LSN with operator support, so you can
> > write things like
> >
> >     cmp_ok($got_lsn, "<", $expected_lsn, "testname")
> >
> > in TAP tests and get sensible results without any concern for LSN
> > representation details, locale, etc. You can subtract LSNs to get a
> > byte difference too.
>
> In my experience, any TAP tests making use of LSN operations can just
> let the backend do the maths, so I am not much a fan of duplicating
> that stuff in a perl module.  Wouldn't it be better to add an
> equivalent of your add() function in the backend then?  That could
> also get tested in the main regression test suite.

I find it convenient not to have as much log spam. Also, IIRC I needed
it at some points where the target backend(s) were down while I was
testing something related to a backend that was still in recovery and
not yet available for querying.

I don't really mind though, I'm just sharing what I have found useful.

On 2020/12/01 14:58, Michael Paquier wrote:
> On Tue, Dec 01, 2020 at 12:03:41PM +0800, Craig Ringer wrote:
>> I'd like to share the attached PG_LSN.pm module that I use when
>> writing TAP tests. I suggest that it be considered for inclusion in
>> core.
>>
>> It defines a Perl datatype PG_LSN with operator support, so you can
>> write things like
>>
>>      cmp_ok($got_lsn, "<", $expected_lsn, "testname")
>>
>> in TAP tests and get sensible results without any concern for LSN
>> representation details, locale, etc. You can subtract LSNs to get a
>> byte difference too.
> 
> In my experience, any TAP tests making use of LSN operations can just
> let the backend do the maths, so I am not much a fan of duplicating
> that stuff in a perl module.

Agreed.

> Wouldn't it be better to add an
> equivalent of your add() function in the backend then?

You mean the same function as the commit 9bae7e4cde provided?

Regards,

-- 
Fujii Masao
Advanced Computing Technology Center
Research and Development Headquarters
NTT DATA CORPORATION

On Tue, Dec 01, 2020 at 03:14:06PM +0900, Fujii Masao wrote:
> You mean the same function as the commit 9bae7e4cde provided?

Completely forgot about this one, thanks.

/me hides
--
Michael