flake8 plugins using pyproject.toml (this plugin)

[christianparpart]

Nice, however, @john-hen,

I am kinda new to flake8, but I have to create a flake8 plugin and it is mandatory for me to use pyproject.toml. I wasn't really successful so far. I have a standalone checker script, that's using the ast module to treewalk and do what I want to check for. We decided to go for flake8 rather than pylint, because pylint already is very much slower than flake8, and the ast module is totally sufficient to what I want to check for.

But we do not want to have any setup.cfg / setup.py files and the likes, but only pyproject.toml and have the project (here: flake8 plugin) configured using this.

I'm asking here because maybe it's already possible and I just didn't see the solution right in front of my eyes. :-)

[john-hen]

What do you mean, you weren't successful? What problem did you actually run into? I don't see how your use case is different from everyone else's: there's Python code that needs linting, and Flake8 is configured in pyproject.toml.

[christianparpart]

I mean, I code like this in my test case:

(flake8_path / "test.py").write_text(code)
result = flake8_path.run_flake8()
assert len(result.out_lines) == expected_errors

And its result.exit_code is always 0 (success), even though sometimes code contains faulty code.

I figured that run_flake8 is actually invoking the binary using process spawn rather than using flake8 as a module. And most likely it doesn't know about my plugin, because how should it know about it. I'd need to point it to some file that contains my checker.

There is the --require-plugins FOOS option, so it seems, but it's not giving me a way to tell flake8 where this plugin is located in.

It is not yet installed, because this is literally the flake8 plugin git repository, that I want to self-test, of course.

I now wonder how to procede from here. :)

p.s.: The flake8 plugin I am working on is here

[john-hen]

It is good practice (if not "best practice", as they say) to install the package that you're testing. During development with pip install --editable . so that you can keep working on the code. If everything is properly set up, Flake8 then knows about your plugin the same way it would otherwise: because you've defined a Flake8 entry point in pyproject.toml.

It's how this project here is set up too. The test suite assumes that Flake8-pyproject is already installed, and in CI we simply install it before running the tests.