Use the tox-oldest plugin

[nstarman]

What is the problem this feature will solve?

We should get rid of our manual specification of oldest dependencies in tox.ini and instead use the constraints from our pyproject.toml

Describe the desired outcome

tox's oldestdeps environment should pull in the oldest version information from pyproject.toml. We should only have to specify version info in one place, not in both the toml and tox.ini.

Additional context

I asked chat-gpt to solve this:

Got it, you want to use tox with your pyproject.toml file to create an environment called "oldestdeps" that installs the oldest version of each dependency. You can achieve this by configuring tox to use the tox-oldest plugin.

Here's how you can do it:

1. Install tox-oldest:
   First, you need to install the tox-oldest plugin:

   pip install tox-oldest
   

2. Update your pyproject.toml:
   Make sure your pyproject.toml contains the dependencies you want to test with. Specify the constraints for each dependency if necessary.

3. Create a tox.ini file:
   In your project directory, create a tox.ini file and configure it to use the tox-oldest plugin.

   Example tox.ini:

   [tox]
   envlist = oldestdeps
   
   [testenv]
   deps = tox-oldest
   
   [testenv:oldestdeps]
   deps =
       tox-oldest
   commands =
       tox-oldest

4. Run tox:
   Now you can run tox with the specified environment oldestdeps:

   tox -e oldestdeps
   

This will create an environment named "oldestdeps" and install the oldest version of each dependency specified in your pyproject.toml file. Make sure to review the output to ensure that the correct versions are being installed.

With this setup tox will directly use your pyproject.toml file for dependency management.

[nstarman]

perhaps a Chat-GPT hallucination. Too good to be true!

[astrofrog]

Next prompt for ChatGPT: could you write the main plugin code for tox-oldest?

[MridulS]

Wait can't we do this with #16201? --resolution=lowest-direct is supported by uv and the oldestdep requirements can be spun up on demand with that.

[nstarman]

Yes please.