pessimist

The name "optimist" was already taken?

Given your listed requirements, and how to run your tests, tries various versions to ensure the minimums are accurate.

Usage

python -m pessimist [-c 'make test'] [--fast] [--extend=name[,name...]] [--requirements=requirements*.txt] /path/to/repo

• -c -- command to run. If you're using a src/ layout you can use cd src; python -m unittest or so.
• --fast -- only verify min and max versions
• --extend -- ignore specifiers entirely for the listed canonical names; intended to let you go back past == and may be improved to do something more like that in the future. Also allows * as a name to mean all names that are "variable"
• --requirements -- comma-separated globs which represented "fixed" requirements.
• --verbose -- show logs as it's working

Fixed and variable

• Fixed requirements are from requirements*.txt. If these match more than one version, only the newest is kept.
• Variable requirements are from your setup.py/setup.cfg/etc that make it into the metadata. These are the ones we're interested in trying.
• If a name is in both sets, the variable logic is followed.

Strategy

1. Try newest versions of everything. Bail if this fails to pass.
2. For each dep independently, try progressively older versions.
3. Try oldest versions of all. Bail if this fails to pass.

I subscribe to the "requirements.txt should be concrete versions you want to use in CI" school of thought; the constraints in setup.py/setup.cfg/pyproject.toml should be >= the minimum version that works, and < the next major version ("compatible", in poetry terms).

My goal in creating this is to have an automated check that we haven't broken compatibility with an older version unintentionally. You could have a simpler version of this that does sed -e 's/>=/==/ on your requirements files, but if that fails, finding the new minimum is still a research projct that's automated by this one.

License

pessimist is copyright Tim Hatch, and licensed under the MIT license. I am providing code in this repository to you under an open source license. This is my personal repository; the license you receive to my code is from me and not from my employer. See the LICENSE file for details.