pytest.main() and plugin registration

[sashko1988]

Why doesn't xdist pass the plugin list to workers when pytest is called with pytest.main()?

Imagine a wrapper that calls pytest like that - pytest.main(args, ["package.needed_plugins"]). And needed_plugins adds cli option and process that option.
Every time pytest is invoked in distribution mode - workers will crash because of an unrecognized argument (which is added and processed by one of the plugins)

When xdist creates a worker, it always passes plugins=None to pytest._prepareconfig: config = _prepareconfig(args, None)
(https://github.com/pytest-dev/pytest-xdist/blob/master/src/xdist/remote.py#L418)

Unexpectedly, the plugin registered without troubles in the controller node isn't passed to workers.

WORKAROUND
Load plugins passing them in args using -p argument (https://docs.pytest.org/en/stable/how-to/writing_plugins.html#plugin-discovery-order-at-tool-startup point 3)

[RonnyPfannschmidt]

Because it cannot know how to create these objects

Plugins must explicitly handle this themselves

[sashko1988]

Got it. thanx

[RonnyPfannschmidt]

On a extra note

If its a specific mofule use the -p my.module cli option as these are handled