tests: add --db-backend pytest option

[danielhollas]

Pair coded and discussed with @GeigerJ2 🫶

Instead of choosing the database backend (SQLite or Postgres) implicitly via markers, we add an explicit --db-backend option to pytest.

  --db-backend=DB_BACKEND
                        Database backend to be used for tests ('sqlite', 'psql')

Important

The default backend was changed from psql to sqlite to make local testing easier.
The tests running in CI are still using Postgres in most places.
The only change in CI should be switching the rabbitmq tests and release tests to use sqlite.

Here's the error if the user provides an invalid option

❯ pytest --db-backend=invalid
ERROR: Invalid --db-backend option 'invalid'
Must be one of: ('sqlite', 'psql')

EDIT: To clarify, the existing presto marker works as before.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.90%. Comparing base (ef60b66) to head (a22f08b).
Report is 136 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #6625      +/-   ##
==========================================
+ Coverage   77.51%   77.90%   +0.40%     
==========================================
  Files         560      567       +7     
  Lines       41444    42147     +703     
==========================================
+ Hits        32120    32831     +711     
+ Misses       9324     9316       -8     

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[danielhollas]

I have no idea if this benchmark alert works, somebody should test it :-)

[danielhollas]

These tests should perhaps live in test_conftest.py

[GeigerJ2]

Just went through a first time, but my brain is mush at this point. Will take it for another spin tomorrow. Just for clarification, because I'm still rather new to this whole CI business: Now, with the PSQL installation removed from the GH workflows, how/when are tests ever ran with PSQL (and I assume by default then only the ones marked with requires_psql).

[GeigerJ2]

Thanks for this feature, @danielhollas, very nice. LGTM from my side!

[unkcpz]

I also give a late review for the PR. Neat test feature!

[danielhollas]

Thanks for the reviews!

(btw: I don't have commit rights to this repo so please merge when you want)

[GeigerJ2]

Thanks for the great work, @danielhollas! I just squash-merged this, using a slightly modified version of your PR description as the commit message. Hope that's OK for you!

[danielhollas]

Hope that's OK for you!

Of course! Thanks for taking this over the finish line, I appreciate it!