DM-34377: Add postgres testing for butler (including datastore)

[timj]

This will hopefully catch the problem fixed by #675. We do not run postgres tests on Jenkins but we do run them in github actions. This test does fail if #675 is not applied.

Checklist

• ran Jenkins
• added a release note for user-visible changes to doc/changes

[codecov]

Codecov Report

Merging #676 (2f7c96a) into main (43ed8f7) will increase coverage by 0.03%.
The diff coverage is 94.00%.

@@            Coverage Diff             @@
##             main     #676      +/-   ##
==========================================
+ Coverage   84.26%   84.29%   +0.03%     
==========================================
  Files         242      242              
  Lines       30971    31019      +48     
  Branches     5217     5219       +2     
==========================================
+ Hits        26097    26149      +52     
+ Misses       3707     3706       -1     
+ Partials     1167     1164       -3     

Impacted Files	Coverage Δ
tests/test_butler.py	97.55% <94.00%> (-0.17%)	⬇️
python/lsst/daf/butler/_butler.py	81.33% <0.00%> (+0.31%)	⬆️
...n/lsst/daf/butler/registry/interfaces/_database.py	87.53% <0.00%> (+0.49%)	⬆️
...n/lsst/daf/butler/registry/databases/postgresql.py	78.86% <0.00%> (+1.03%)	⬆️
python/lsst/daf/butler/tests/utils.py	94.04% <0.00%> (+1.19%)	⬆️

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[andy-slac]

Looks good. General comment - the server setup logic repeats some of the test_postgresql.py, would it be worth to move it to a common base class?

[timj]

test_postgresql.py does the setup a slightly different way. I tried using that way but the tests got a bit upset. I therefore switched to the caching scheme recommended in the testing.postgresql docs. I also tried switching test_postgresql.py over to that approach but it took 10% longer to run the tests that way. If we don't mind that slowdown I can move the setUp/teadDown[class] code to a helper class.

[andy-slac]

Is it 10% for test_postgresql.py or the whole test? I'm OK with leaving it as it is now, and let the next person who also needs postgres to refactor it.

[timj]

The entire run of test_postgresql.py went from 60 seconds to 70 seconds when I used the postgre cache factory thing.