Rework migrations

[ewjoachim]

Closes #

WIP work, but I've been blocking for too long already on this.
This is a new take on acceptance tests:

• They're run as subprocess, as before
• But in a dedicated venv
• And can be run with multiple configuration (but the same tests will run)

As a start, I created 4 tests:

• Normal conditions (current code, all migrations)
• Run on the last release of procrastinate with just the pre-migrations (currently failing! @medihack, see below)
• Run on the current code with just the pre-migrations
• Normal conditions but use aiopg (currently not working, due to not specifying that we need the aiopg extra in the venv)

What's missing:

• Fix the 2 failing test
• Add some other combinations ?
• The operations we run on each test are very minimal, we should test a few more things (see existing acceptance tests)
• Remove acceptance tests once we test (mostly?) everything in the new tests. and remove this ugly "2" in the folder name
• Add LATEST_TAG envvar in the CI to avoid reading the latest tag from the git tags during the tests. I don't trust our CI git clone to do it properly. Instead use gh releases something
• Add a Readme explaining what the hell this whole thing is and how to contribute

Successful PR Checklist:

• Tests
  • (not applicable?)
• Documentation
  • (not applicable?)

PR label(s):

• PR type: breaking 💥 Contains breaking changes
• PR type: feature ⭐️ Contains new features
• PR type: bugfix 🕵️ Contains bug fix
• PR type: miscellaneous 👾 Contains misc changes
• PR type: dependencies 🤖 Contains only dependencies updates
• PR type: documentation 📚 Contains documentation updates

The interesting error we got on running procrastinate 2.x with pre-migrations:

E           tests.acceptance2.utils.SubprocessException: Subprocess failed (code 1) with stdout:  and stderr: Launching a job: app.t1(a=1)
E           function procrastinate_defer_job_v1(unknown, unknown, smallint, unknown, unknown, jsonb, unknown) does not exist
E           LINE 1: SELECT procrastinate_defer_job_v1($1, $2, $3, $4, $5, $6, $7...
E                          ^
E           HINT:  No function matches the given name and argument types. You might need to add explicit type casts.
E           Database error.

[github-actions]

Coverage report

Click to see where and how coverage changed

File	Statements	Missing	Coverage	Coverage (new stmts)	Lines missing
procrastinate
manager.py
Project Total

This report was generated by python-coverage-comment-action

[ewjoachim]

Woo, it's green in the CI! Promising :) Thank you for the pair @medihack !

[medihack]

For using nox, I started working in a new branch and also a new PR #1245