Reports missing dependency when setuptools version is in build-system

[mauritsvanrees]

I was typing this issue report, but halfway through realised it was not actually a problem with z3c.dependencychecker. Let me file the report anyway, in case others fall into the same trap, and then close it immediately.

In pyproject.toml you can specify a build system, so that modern packaging techniques and agreements are used:

[build-system]
requires = ["setuptools", "wheel"]

dependencychecker has no problem with this.

But when you require a minimum version (or a maximum, or an explicit version) like this:

[build-system]
requires = ["setuptools>=68.2", "wheel"]

then dependencychecker gives an error:

ERROR Missing dependencies:
	setuptools>=68.2

setuptools itself is already in install_requires.

Hey, I wonder if it somehow sees the full string setuptools>=68.2 as package name.
When a dependency in install_requires has a minimum version, this goes fine though.

See this PR: plone/plone.app.event#385
And this background issue where setuptools 68.1.* is not working for plone.app.* namespace packages: plone/meta#172

---

Hang on, who is actually printing "Missing dependencies"? Because in the dependencychecker code I only see "Missing requirements".

Aha, tox -e dependencies is defined this way:

[testenv:dependencies]
description = check if the package defines all its dependencies
skip_install = true
deps =
    build
    z3c.dependencychecker==2.11
commands =
    python -m build --sdist --no-isolation
    dependencychecker

And it already fails on the first command, the python -m build.
And this now fails due to the --no-isolation option, because the tox env does not have the required setuptools version...
When I remove this option, everything works again. And to avoid false positives: when I remove a requirement from setup.py, we do get a "Missing requirements" error.

Looks like we should remove the option in our setup. But need to check if we had a good reason for this.

Anyway, I will close this short-lived bug report now. :-)