Thread: In which good intentions are punished, take 2

Since I committed 49c817eab78c6f0ce8c3bf46766b73d6cf3190b7 to make
pg_do_encoding_conversion not fail silently, buildfarm member magpie
has been whining:
http://buildfarm.postgresql.org/cgi-bin/show_log.pl?nm=magpie&dt=2014-02-25%2011%3A00%3A08

To wit, that if you run contrib/citext's regression tests in a
LATIN2-encoded database, you get this:
 SELECT convert_to( name, 'ISO-8859-1' ) = convert_to( name::text, 'ISO-8859-1' ) AS t FROM srt;
! ERROR:  default conversion function for encoding "LATIN2" to "LATIN1" does not exist

Well, it's right, there is no such conversion function.  A quick look
in the buildfarm logs for older runs confirms that previously, all
we were getting was the useless LOG bleats that the previous coding
emitted:

LOG:  default conversion function for encoding "LATIN2" to "LATIN1" does not exist
STATEMENT:  SELECT convert_to( name, 'ISO-8859-1' ) = convert_to( name::text, 'ISO-8859-1' ) AS t FROM srt;

That didn't appear in the user-visible output, allowing the regression
test to appear to "pass" although under no circumstances could it be
argued that what was happening was sane.

We could possibly replace this test case with

SELECT convert_from( name::bytea, 'SQL_ASCII' ) = convert_from( name::text::bytea, 'SQL_ASCII' ) AS t FROM srt;

though I'm not sure I see the point: whatever you might think this
statement is testing, it's not got much to do with citext.  On the
other hand, we evidently have got precious little other buildfarm
coverage of the convert() family of functions, so maybe removing
this test altogether wouldn't be the best thing either.

Thoughts?
        regards, tom lane

Tom Lane wrote:

> On the
> other hand, we evidently have got precious little other buildfarm
> coverage of the convert() family of functions, so maybe removing
> this test altogether wouldn't be the best thing either.

We do have precious little testing on encodings and conversions, yes.
The problem is how to test these things without having the tests fail
when any particular encoding is not installed in the test system.

Maybe we can use the Perl test rig for this too: Peter said that if a
test requires something not installed, the test is skipped without
causing a failure.  It seems to me that we could take advantage that so
that each member tests whatever involves only the encodings it has
installed; while each individual member would skip a large percentage of
tests, the buildfarm as a whole would be testing a sizable portion, if
not all of it.

-- 
Álvaro Herrera                http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Training & Services

On 02/25/2014 08:53 PM, Alvaro Herrera wrote:
> Tom Lane wrote:
>
>> On the
>> other hand, we evidently have got precious little other buildfarm
>> coverage of the convert() family of functions, so maybe removing
>> this test altogether wouldn't be the best thing either.
> We do have precious little testing on encodings and conversions, yes.
> The problem is how to test these things without having the tests fail
> when any particular encoding is not installed in the test system.
>
> Maybe we can use the Perl test rig for this too: Peter said that if a
> test requires something not installed, the test is skipped without
> causing a failure.  It seems to me that we could take advantage that so
> that each member tests whatever involves only the encodings it has
> installed; while each individual member would skip a large percentage of
> tests, the buildfarm as a whole would be testing a sizable portion, if
> not all of it.
>


It should be easy (at least on *nix) for the buildfarm client to check 
what encodings are installed on the machine and run tests accordingly. I 
haven't been following closely, but if someone provides me with a simple 
spec I'll try to code it up. We're about due for a release anyway.

cheers

andrew